sprouting and germination
How to Sprout Seeds
for Maximum Nutrition
Seeds and nuts contain enzyme inhibitors that must be broken down before the seed will germinate. In nature this commonly occurs in the spring time, as the weather gets warmer and the soil is nice and damp. The purpose of the enzyme inhibitors is to ensure the seed or nut only begins to sprout when the weather conditions are favorable. By soaking seeds and nuts in the warmth of your home, their enzyme inhibitors are broken down, and they become more nutritious and easier to digest.
Many seeds and nuts such as hulled sunflowers, pumpkin seeds, and almonds do not really sprout, but still benefit from being soaked in water.
When seeds and nuts are soaked their fat content decreases, and they become a better source of easily digestible protein.
It’s important that the nuts or seeds you use for sprouting are raw and not roasted or salted.
How to sprout hulled sunflower seed
Hulled sunflower seed is the kernel of the seed with its shell removed. Before soaking pick out any chipped or damaged seeds.
- Place the desired amount of sunflower seed in a bowl or jar.
- Cover them with twice the amount of water, and gently encourage any floating on the top to sink. If some seeds continue to float it may mean they are damaged or rancid and are best removed.
- Leave to soak in a warm place for 1 to 4 hours, or overnight in the fridge.
- Rinse them gently until the water runs clean. Either use a sieve or a clean hand to stop them escaping down the drain.
- Enjoy these sunflower sprouts just as they are, sprinkled onto salads, added to smoothies and puddings, or used to make great raw pâtés and pestos.
Stored in fresh water they will keep in the fridge for 24 hours.
How to sprout almonds
Lovely juicy plump almonds. These are one of my favorite sprouts.
- Place one cup of almonds in bowl or sprouting jar and cover with two cups of water.
- Leave to soak somewhere warm for 8-12 hours or overnight.
- Rinse well.
- The almonds should now be large and plump. They will not grow a sprout and can be eaten just as they are.
- Soaked almonds make great snacks, nut milks, and pâtés. They are a tasty addition to salads too.
- Soaked almonds keep well, and can be stored covered with fresh water in a container in your fridge. If you change the water every day they will keep for 3-5 days.
Soaked almonds taste and store better with their brown skins removed. Depending on how long the almonds have been soaked for the almond skins may come off easily with your fingers – one of those things that gets easier with practice! If the skins seem on tight then you can blanch the almonds in hot water for about 10 seconds. Don’t leave them too long or they’ll cook! The skins should then be easier to remove. Damaged or rancid almonds contain green or brown rather than pure white, and are softer than healthy nuts.
If I’m snacking on the almonds or adding them to salads then I like to remove their skins, and if I’m making almond milk I leave them on.
Top 15 Sprouting Seeds For A Raw Food Diet
One of the most delicious aspects of a raw food diet, also known as a live food diet, is sprouting. Sprouting is a process used to remove seed enzyme inhibitors, enabling the seed to germinate or “sprout.” Its a relatively easy and inexpensive way to produce your own healthy, nutrient-rich, flavorful, all natural food source….
One of the most delicious aspects of a raw food diet, also known as a live food diet, is sprouting. Sprouting is a process used to remove seed enzyme inhibitors, enabling the seed to germinate or “sprout.” Its a relatively easy and inexpensive way to produce your own healthy, nutrient-rich, flavorful, all natural food source. It works by first placing the seeds in a sprouting jar or tray.
Next, cover the jar with cheesecloth taking care to secure it with a rubber band. Then, soak the seeds for a proscribed amount of time, which can vary, depending on the type of seeds being sprouted. After seeds have soaked for a sufficient amount of time drain them. Then, over the next few days, rinse then drain the jar of seeds twice a day, usually in the morning then at night. Soon you should have a gorgeous array of green sprouts smiling back at you. Once your seeds have sprouted, you can add your sprouts to any of your favorite live food dishes ranging from salad to live food wraps or meatless burgers. Not only are sprouts a delicious addition to your meal, but they are absolutely packed with pure, live proteins, minerals, vitamins, phytochemicals, essential amino acids and more.
Now if you’re like me, after you’ve heard about all of this you’ll be anxious to get started on this fantastical experience. You’ve got your sprouting jars, cheese cloth and rubber bands and have even viewed several instructional how-to videos on sprouting. However, there’s just one thing. You’re not sure about what seeds are best for sprouting. That’s why I’ve provided a list below of the 15 most commonly sprouted seeds. Just note that for any seeds that you purchase, make sure that they are organic as you don’t want to undo all of nature’s goodness by sprouting pesticide and herbicide-laced seeds. Now without further delay here is the list.
- Mung Beans
- Red Clover
- Mustard Seed
So above is the list of seeds that you should sprout, but I would be doing you an injustice if I didn’t also caution you about the seeds that you may want to either avoid sprouting or exercise care when doing so. Thus, some seeds to avoid sprouting are soy and kidney. These seeds are actually quite toxic, which is nature’s way of safeguarding us and them, so stay away from these. Also, alfalfa, which was not included on the list, has a fairly high level of toxicity and may be sprouted, but should be consumed sparingly.
Amirah Bellamy is a Vegan Coach, Vegan Fitness Meal Planning Expert, and Author. To learn more about her fabulous Vegetarian Meal Plans, purchase her infamous eBook “The 50¢ Book That’s Hotter Than 50 Cent,” or INSTANTLY grab her FREE Vegetarian Starter Kit go towww.AmirahBFit.com
Nuts and Seeds
Nuts are very healthy and nutritious. In addition to being excellent sources of protein, nuts and seeds have many other benefits such as vitamins, minerals, fiber, and other chemicals that may prevent cancer and heart disease. Although many people are hesitant to eat nuts because they are high in fat, eating nuts can provide a sense of fullness or satisfaction that actually causes you to eat less of other high-calorie, high fat foods. Additionally, nuts are high in essential amino acids and healthy fats, making them an important part of any vegan or vegetarian’s diet.
Quick Page Summary: Eating nuts and seeds are a great way to add vitamins, minerals, fiber, and essential fatty acids (like omega 3 and omega 6), to your diet. Some great choices include almonds, cashews, flaxseeds (ground), peanuts, pumpkin seeds, sesame seeds, sunflower seeds, and walnuts. If you have time, you may want to purchase raw nuts and seeds and soak them in purified water for up to 24 hours; this starts the germination process, which makes them much more nutritious.
The world’s healthiest nuts and seeds include:
- Almonds – Almonds are a good source of protein, vitamin E, manganese, magnesium, copper, vitamin B2 (riboflavin), and phosphorus. Almonds are also concentrated in protein; a quarter-cup contains more protein than the typical egg. Although one-quarter cup of almonds contains about 18 grams of fat, most of it (11 grams) is heart-healthy monounsaturated fat. Eating almonds can lower bad cholesterol, reduce the risk of heart disease, provide protection against cardiovascular disease and diabetes, boost energy, and help prevent gallstones. Whole almonds (with skins) provide the most heart-healthy benefits.
- Cashews – Cashews are high in antioxidants and have a lower fat content than most other nuts; additionally, 75 percent of their fat is unsaturated fatty acids. Cashews are also a good source of monounsaturated fats, copper, and a good source of magnesium and phosphorous. Eating cashews promotes good cardiovascular health, even in individuals with diabetes.
- Flaxseeds – Flaxseeds, also known as linseeds, are an excellent source of omega-3 fatty acids. Flaxseeds may provide anti-inflammatory benefits, protect your bones, and protect against heart disease, breast cancer, and diabetes. Eating flaxseeds also lowers blood pressure in men with high cholesterol. Flaxseeds are also rich in fiber and manganese and are a good source of folate, vitamin B6 (pyridoxine), magnesium, phosphorous, and copper, and lignan phytonutrients. You’ll need to grind them up first (or purchase ground flaxseed) to gain the most nutritional benefits.
- Peanuts – Peanuts are a good source of heart-healthy monosaturated fat, flavonoid (resveratrol), antioxidants, phytosterols, phytic acid (inositol hexaphosphate), and folic acid, making them heart-healthy, a good way to reduce your risk of stroke, and possibly even cancer. Peanuts are also a good source of vitamin B3 (niacin), folate, copper, manganese, and protein, and are a significant source of resveratrol, a chemical studied for potential anti-aging effects.. Peanuts and peanut butter may also help prevent gallstones and protect against Alzheimer’s disease. It wise to ensure that peanuts, especially raw ones, are stored in a cool, dry, environment (such as a refrigerator or freezer), as an extremely toxic and highly dangerous fungus (aflatoxin) can easily grow on peanuts when the temperature is between 86-96°F (30-36°C) and humidity is high.
- Pumpkin seeds / pepitas – Eating the green, hulled, pumpkin seeds (also called pepitas) may promote prostate health, protection for men’s bones, anti-inflammatory benefits for those with arthritis, and help lower cholesterol. Pumpkin seeds are a good source of the essential fatty acids, potassium, phosphorous, magnesium, manganese, zinc, iron, and copper, protein, and vitamin K.
- Sesame seeds – Sesame seeds and tahini are rich in beneficial minerals. Not only are sesame seeds a very good source of manganese and copper, but they are also a good source of calcium, magnesium, iron, phosphorous, vitamin B1 (thiamin), zinc, dietary fiber, and healthy (monosaturated) fats. They contain powerful antioxidants called lignans, which are also anti-carcinogenic. They also contain phytosterols, which block cholesterol production. Sesame contains one lignan unique to it called sesamin. Eating sesame seeds may help lower cholesterol, provide relief for rheumatoid arthritis, and support vascular and respiratory health. The nutrients of sesame seeds are better absorbed if they are ground or pulverized before consumption.
- Sunflower seeds – Eating sunflower seeds may help provide anti-inflammatory and cardiovascular benefits, lower cholesterol, and prevent cancer. Sunflower seeds are an excellent source of vitamin E. Sunflower seeds are also an excellent source of linoleic acid (an essential fatty acid), dietary fiber, protein, and minerals such as magnesium and selenium, and are high in cholesterol-lowering phytosterols.
- Walnuts – Walnuts are an excellent source of omega-3 essential fatty acids. Walnuts are also a good source of manganese, and copper. Walnuts are also an important source of healthy (monounsaturated) fats. Eating walnuts may benefit your cardiovascular system, improve cholesterol in individuals with type 2 diabetes, help brain functions, protect bone health, and help prevent gallstones. Walnuts also have bio-available melatonin, which helps regulate sleep. A new study published in the Journal of the American College of Cardiology (Oct. 17, 2006) found that eating walnuts after a meal high in unhealthy fats can reduce the damaging effects of such fats on blood vessels. Walnuts also contain l-arginine, which is an essential amino acid that the body uses to produce nitric oxide, necessary for keeping blood vessels flexible.
*According to the George Mateljan Foundation. See the “World’s Healthiest Foods” web site for more information.
To Soak or Not to Soak…
Although eating nuts and seeds, even when roasted, can be very healthy, it may be beneficial to purchase your nuts and seeds raw and then soak them in clean water for a few hours before eating them. Soaking raw nuts and seeds stimulates the process of germination, which increases the vitamin C, B, and carotenes (pre-vitamin A) content. It may also neutralize phytic acid, a substance present in the bran of all grains and seeds that can inhibit some absorption of calcium, magnesium, iron, copper, and zinc. Raw nuts and seeds also contain enzyme inhibitors that are neutralized by germination.
If you choose to soak your nuts and seeds, please follow these general guidelines:
- Getting ready: Use raw, preferably organic, nuts and seeds. Make enough for three days only. Use a glass or stainless steel bowl or jar (plastics may contain toxins). Rinse your nuts or seeds (purified or distilled water is generally preferred).
- Soak them: Place your nuts and seeds in in the bowl or jar and then cover it with something breathable, like a towel or pantyhose. Let them soak according to the following schedule (all times approximate).
- Almonds, germination time 8 – 12 hours at room temperature
- Cashews, whole, germination time 2 – 2 1/2 hours at room temperature
- Sesame seeds, germination time 8 hours at room temperature
- Sunflower seeds, germination time 2 hours at room temperature
- Walnuts, germination time 4 hours at room temperature
- All other nuts, germination time 6-24 hours at room temperature
Over the course of the soaking, drain and rinse the nuts or seeds two (2) or three (3). Each time you do this, make sure you rinse them until the water drains clear. This is especially important with nuts and seeds that soak for longer amounts of time.
- Afterwards: After you’ve soaked them, you may want to do a final rinse with grapefruit seed extract or organic apple cider vinegar, as these can will clean them of bacteria without being absorbed. You now have germinated nuts and seeds! You’re ready to eat them. You can store the leftovers in the refrigerator for up to three (3) days.
If the idea of soaking your nuts and seeds seems too time-consuming an endeavor for you, don’t worry—many nutrients cannot be heated out of foods, like protein, vitamin E, and fiber, which are found in ample quantities inside nuts and seeds of all kinds, both cooked and uncooked.
Sprouting is the practice of germinating seeds to be eaten either raw or cooked. They are a convenient way to have fresh vegetables for salads, or otherwise, in any season and can be germinated at home or produced industrially. Sprouts are believed to be highly nutritious and rich in enzymes which promote good health. They are a prominent ingredient of the raw food diet and common in Eastern Asian cuisine. Sprouting is also applied on a large scale to barley as a part of the malting process. A downside to consuming raw sprouts is that the process of germinating seeds is conducive to bacterial growth, resulting in dozens of outbreaks of lethal infection with Salmonella and E. coli over the past few decades.
Seeds suitable for sprouting
All viable seeds can be sprouted, but some sprouts should not be eaten raw. The most common food sprouts include:
- Pulses (pea family):
- Vegetables and herbs:
Although whole oats can be sprouted, oat groats sold in food stores, which are dehulled and require steaming or roasting to prevent rancidity, will not sprout. Whole oats may have an indigestible hull which makes them difficult or even unfit for human consumption.
All the sprouts of the solanaceae (tomato, potato, paprika, aubergine or eggplant) and rhubarb cannot be eaten as sprouts, either cooked or raw, as they can be poisonous. Some sprouts can be cooked to remove the toxin, while others cannot.
With all seeds, care should be taken that they are intended for sprouting or human consumption rather than sowing. Seeds intended for sowing may be treated with chemical dressings. Several countries, such as New Zealand, also require that some varieties of imported edible seed be heat-treated, thus making them impossible to sprout. Quinoa in its natural state is very easy to sprout but when polished, or pre-cleaned of its saponin coating (becoming whiter), loses its power to germinate.
The germination process
The germination process that lasts few days, can be done at home manually, as semi-automated process or industrially when done on a large scale for commercial use.
The seeds are normally first soaked and depending on the type of seed this process can take anything from 20 minutes up to 12 hours. Before soaking, the seeds are rinsed to remove soil and dirt and mucilaginous substances produced by some seeds when they come in contact with water. The soaking increases the water content in the seeds and brings them out of quiescence.
It follows draining and then rinsing seeds at regular intervals until they germinate, or sprout.
To sprout seeds, the seeds are moistened, then left at room temperature (between 13 and 21 °C or 55 and 70 °F) in a sprouting vessel. Many different types of vessels can be used. One type is a simple glass jar with a piece of cloth secured over its rim. ‘Tiered’ clear plastic sprouters are commercially available, allowing a number of “crops” to be grown simultaneously. By staggering sowings, a constant supply of young sprouts can be ensured. Any vessel used for sprouting must allow water to drain from it, because sprouts that sit in water will rot quickly. The seeds will swell and begin germinating within a day or two.
Sprouts are rinsed between twice a day and three or four times a day accordingly with climate and type of seed, to prevent them from souring and providing them with moisture. Each seed has its own ideal sprouting time. Depending on which seed is used, after three to five days they will have grown to 5 to 8 centimetres (2–3 in) in length and will be suitable for consumption. If left longer they will begin to develop leaves, and are then known as baby greens. A popular baby green is sunflower after 7–10 days. The growth process of any sprout can be slowed or halted by refrigerating until needed.
Common causes for sprouts to become inedible:
- Seeds are allowed to dry out
- Seeds are left in standing water
- Temperature is high or too low
- Insufficient rinsing
- Dirty equipment
- Insufficient air flow
- Contaminated source of water
- Poor rate of germination of seed
Mung beans can be sprouted either in light or dark conditions. Those sprouted in the dark will be crisper in texture and whiter, as in the case of commercially available Chinese Bean Sprouts, but these have less nutritional content than those grown in partial sunlight. Growing in full sunlight is not recommended, because it can cause the beans to overheat or dry out. Subjecting the sprouts to pressure, for example, by placing a weight on top of them in their sprouting container, will result in larger, crunchier sprouts similar to those sold in Polish grocery stores.
A very effective way to sprout beans like lentils or azuki is in colanders. Soak the beans in water for about 8 hours then place in the colander. Wash twice a day. The sprouted beans can be eaten raw or cooked.
Sprouting is also applied on a large scale to barley as a part of the malting process. Malted barley is an important ingredient in beer and is used in huge quantities. Most malted barley is distributed among wide retail sellers in North American regions.
Many varieties of nuts, such as almonds and peanuts, can also be started in their growth cycle by soaking and sprouting, although because the sprouts are generally still very small when eaten, they are usually called “soaks”.
 Nutritional information
Sprouts are said to be rich in digestible energy, bioavailable vitamins, minerals, amino acids, proteins, and phytochemicals, as these are necessary for a germinating plant to grow. These nutrients are essential for human health. To clarify, the nutritional changes upon germination & sprouting have been summarized below. Chavan and Kadam (1989) concluded that – “The desirable nutritional changes that occur during sprouting are mainly due to the breakdown of complex compounds into a more simple form, transformation into essential constituents and breakdown of nutritionally undesirable constituents.”
“The metabolic activity of resting seeds increases as soon as they are hydrated during soaking. Complex biochemical changes occur during hydration and subsequent sprouting. The reserve chemical constituents, such as protein, starch and lipids, are broken down by enzymes into simple compounds that are used to make new compounds.”
“Sprouting grains causes increased activities of hydrolytic enzymes, improvements in the contents of total proteins, fat, certain essential amino acids, total sugars, B-group vitamins, and a decrease in dry matter, starch and anti-nutrients. The increased contents of protein, fat, fibre and total ash are only apparent and attributable to the disappearance of starch. However, improvements in amino acid composition, B-group vitamins, sugars, protein and starch digestibilities, and decrease in phytates and protease inhibitors are the metabolic effects of the sprouting process.”
Increases in Protein Quality Chavan and Kadam (1989) stated – “Very complex qualitative changes are reported to occur during soaking and sprouting of seeds. The conversion of storage proteins of cereal grains into albumins and globulins during sprouting may improve the quality of cereal proteins. Many studies have shown an increase in the content of the amino acid Lysine with sprouting.”
“An increase in proteolytic activity during sprouting is desirable for nutritional improvement of cereals because it leads to hydrolysis of prolamins and the liberated amino acids such as glutamic and proline are converted to limiting amino acids such as lysine.”
Increases in Crude Fibre content Cuddeford (1989), based on data obtained by Peer and Leeson (1985), stated – “In sprouted barley, crude fibre, a major constituent of cell walls, increases both in percentage and real terms, with the synthesis of structural carbohydrates, such as cellulose and hemicellulose”. Chung et al. (1989) found that the fibre content increased from 3.75% in unsprouted barley seed to 6% in 5-day sprouts.”
Crude Protein and Crude Fibre changes in Barley Sprouted over a 7-day period
Crude Protein Crude Fibre (% of DM) (% of DM)
Original seed 12.7% 5.4% Day 1 12.7% 5.6% Day 2 13.0% 5.9% Day 3 13.6% 5.8% Day 4 13.4% 7.4% Day 5 13.9% 9.7% Day 6 14.0% 10.8% Day 7 15.5% 14.1%
Source: Cuddeford (1989), based on data obtained by Peer and Leeson (1985).
Increases in Essential Fatty Acids
An increase in lipase activity has been reported in barley by MacLeod and White (1962) , as cited by Chavan and Kadam (1989) . Increased lipolytic activity during germination and sprouting causes hydrolysis of triacylglycerols to glycerol and constituent fatty acids.
Increases in Vitamin content According to Chavan and Kadam (1989) , most reports agree that sprouting treatment of cereal grains generally improves their vitamin value, especially the B-group vitamins. Certain vitamins such as α-tocopherol (Vitamin-E) and β-carotene (Vitamin-A precursor) are produced during the growth process (Cuddeford, 1989) .
According to Shipard (2005) – “Sprouts provide a good supply of Vitamins A, E & C plus B complex. Like enzymes, vitamins serve as bioactive catalysts to assist in the digestion and metabolism of feeds and the release of energy. They are also essential for the healing and repair of cells. However, vitamins are very perishable, and in general, the fresher the feeds eaten, the higher the vitamin content. The vitamin content of some seeds can increase by up to 20 times their original value within several days of sprouting. Mung Bean sprouts have B vitamin increases, compared to the dry seeds, of – B1 up 285%, B2 up 515%, B3 up 256%. Even soaking seeds overnight in water yields greatly increased amounts of B vitamins, as well as Vitamin C. Compared with mature plants, sprouts can yield vitamin contents 30 times higher.”
Chelation of Minerals Shipard (2005) claims that – “When seeds are sprouted, minerals chelate or merge with protein, in a way that increases their function.”
It is important to note that while these changes may sound impressive, the comparisons are of dormant, non-sprouted seed to sprouted seed rather than comparisons of sprouts to normal sized vegetables.
 Health concerns
 Bacterial infection
Commercially grown sprouts are associated with multiple outbreaks of harmful bacteria like salmonella or the toxic forms of Escherichia coli. Such infections, which are so frequent in the United States that investigators call them “sproutbreaks”, may be a result of contaminated seeds or of unhygienic production with high microbial counts. Sprout seeds can become contaminated in the fields where they are grown, and sanitizing steps may be unable to kill bacteria hidden in damaged seeds. A single surviving bacterium in a kilogram of seed can be enough to contaminate a whole batch of sprouts, according to the FDA.
To minimize the impact of the incidents and maintain public health, both the U.S. Food and Drug Administration (FDA) and Health Canada issued industry guidance on the safe manufacturing of edible sprouts and public education on their safe consumption. There are also publications for hobby farmers on safely growing and consuming sprouts at home. The recommendations include development and implementation of good agricultural practices and good manufacturing practices in the production and handling of seeds and sprouts, seed disinfection treatments, and microbial testing before the product enters the food supply.
In June 2011, contaminated bean sprouts in Germany were identified as the source of the 2011 E. coli O104:H4 outbreak. In addition to Germany, where 3,792 cases and 42 deaths had been reported as of 22 June, a handful of cases have been reported in several countries including Switzerland, Poland, the Netherlands, Sweden, Denmark, the UK, Canada and the USA. Essentially all affected people had been in Germany shortly before becoming ill.
 Antinutritional factors
Some legumes, including sprouts, can contain toxins or antinutritional factors, which can be reduced by soaking, sprouting and cooking (e.g., stir frying). Joy Larkcom advises that to be on the safe side “one shouldn’t eat large quantities of raw legume sprouts on a regular basis, no more than about 550g (20oz) daily”.
Phytic acid, an antinutritional factor, occurs primarily in the seed coats and germ tissue of plant seeds. It forms insoluble or nearly insoluble compounds with many metal ions, including those of calcium, iron, magnesium and zinc, reducing their dietary availability. Diets high in phytic acid content and poor in these minerals produce mineral deficiency in experimental animals (Gontzea and Sutzescu, 1958, as cited in Chavan and Kadam, 1989). The latter authors state that the sprouting of cereals has been reported to decrease levels of phytic acid. Similarly, Shipard (2005) states that enzymes of germination and sprouting can help eliminate detrimental substances such as phytic acid. However, the amount of phytic acid reduction from soaking is only marginal, and not enough to counteract its antinutrient effects 
 See also
Germination is the process in which a plant or fungus emerges from a seed or spore, respectively, and begins growth. The most common example of germination is the sprouting of a seedling from a seed of an angiosperm or gymnosperm. However the growth of a sporeling from a spore, for example the growth of hyphae from fungal spores, is also germination. In a more general sense, germination can imply anything expanding into greater being from a small existence or germ.
 Seed germination
Germination is the growth of an embryonic plant contained within a seed; it results in the formation of the seedling. The seed of a higher plant is a small package produced in a fruit or cone after the union of male and female sex cells. All fully developed seeds contain an embryo and, in most plant species some store of food reserves, wrapped in a seed coat. Some plants produce varying numbers of seeds that lack embryos; these are called empty seeds and never germinate. Most seeds go through a period of quiescence where there is no active growth; during this time the seed can be safely transported to a new location and/or survive adverse climate conditions until circumstances are favorable for growth. Quiescent seeds are ripe seeds that do not germinate because they are subject to external environmental conditions that prevent the initiation of metabolic processes and cell growth. Under favorable conditions, the seed begins to germinate and the embryonic tissues resume growth, developing towards a seedling.
 Factors affecting seed germination
Seed germination depends on both internal and external conditions. The most important external factors include temperature, water, oxygen and sometimes light or darkness. Various plants require different variables for successful seed germination. Often this depends on the individual seed variety and is closely linked to the ecological conditions of a plant’s natural habitat. For some seeds, their future germination response is affected by environmental conditions during seed formation; most often these responses are types of seed dormancy.
- Water – is required for germination. Mature seeds are often extremely dry and need to take in significant amounts of water, relative to the dry weight of the seed, before cellular metabolism and growth can resume. Most seeds need enough water to moisten the seeds but not enough to soak them. The uptake of water by seeds is called imbibition, which leads to the swelling and the breaking of the seed coat. When seeds are formed, most plants store a food reserve with the seed, such as starch, proteins, or oils. This food reserve provides nourishment to the growing embryo. When the seed imbibes water, hydrolytic enzymes are activated which break down these stored food resources into metabolically useful chemicals. After the seedling emerges from the seed coat and starts growing roots and leaves, the seedling’s food reserves are typically exhausted; at this point photosynthesis provides the energy needed for continued growth and the seedling now requires a continuous supply of water, nutrients, and light.
- Oxygen – is required by the germinating seed for metabolism. Oxygen is used in aerobic respiration, the main source of the seedling’s energy until it grows leaves. Oxygen is an atmospheric gas that is found in soil pore spaces; if a seed is buried too deeply within the soil or the soil is waterlogged, the seed can be oxygen starved. Some seeds have impermeable seed coats that prevent oxygen from entering the seed, causing a type of physical dormancy which is broken when the seed coat is worn away enough to allow gas exchange and water uptake from the environment.
- Temperature – affects cellular metabolic and growth rates. Seeds from different species and even seeds from the same plant germinate over a wide range of temperatures. Seeds often have a temperature range within which they will germinate, and they will not do so above or below this range. Many seeds germinate at temperatures slightly above room-temperature 60-75 F (16-24 C), while others germinate just above freezing and others germinate only in response to alternations in temperature between warm and cool. Some seeds germinate when the soil is cool 28-40 F (-2 – 4 C), and some when the soil is warm 76-90 F (24-32 C). Some seeds require exposure to cold temperatures (vernalization) to break dormancy. Seeds in a dormant state will not germinate even if conditions are favorable. Seeds that are dependent on temperature to end dormancy have a type of physiological dormancy. For example, seeds requiring the cold of winter are inhibited from germinating until they take in water in the fall and experience cooler temperatures. Four degrees Celsius is cool enough to end dormancy for most cool dormant seeds, but some groups, especially within the family Ranunculaceae and others, need conditions cooler than -5 C. Some seeds will only germinate after hot temperatures during a forest fire which cracks their seed coats; this is a type of physical dormancy.
Most common annual vegetables have optimal germination temperatures between 75-90 F (24-32 C), though many species (e.g. radishes or spinach) can germinate at significantly lower temperatures, as low as 40 F (4 C), thus allowing them to be grown from seed in cooler climates. Suboptimal temperatures lead to lower success rates and longer germination periods.
- Light or darkness – can be an environmental trigger for germination and is a type of physiological dormancy. Most seeds are not affected by light or darkness, but many seeds, including species found in forest settings, will not germinate until an opening in the canopy allows sufficient light for growth of the seedling.
Scarification mimics natural processes that weaken the seed coat before germination. In nature, some seeds require particular conditions to germinate, such as the heat of a fire (e.g., many Australian native plants), or soaking in a body of water for a long period of time. Others need to be passed through an animal’s digestive tract to weaken the seed coat enough to allow the seedling to emerge.
Some live seeds are dormant and need more time, and/or need to be subjected to specific environmental conditions before they will germinate. Seed dormancy can originate in different parts of the seed, for example, within the embryo; in other cases the seed coat is involved. Dormancy breaking often involves changes in membranes, initiated by dormancy-breaking signals. This generally occurs only within hydrated seeds. Factors affecting seed dormancy include the presence of certain plant hormones, notably abscisic acid, which inhibits germination, and gibberellin, which ends seed dormancy. In brewing, barley seeds are treated with gibberellin to ensure uniform seed germination for the production of barley malt.
 Seedling establishment
In some definitions, the appearance of the radicle marks the end of germination and the beginning of “establishment”, a period that ends when the seedling has exhausted the food reserves stored in the seed. Germination and establishment as an independent organism are critical phases in the life of a plant when they are the most vulnerable to injury, disease, and water stress. The germination index can be used as an indicator of phytotoxicity in soils. The mortality between dispersal of seeds and completion of establishment can be so high that many species have adapted to produce huge numbers of seeds.
 Germination rate
In agriculture and gardening, the germination rate describes how many seeds of a particular plant species, variety or seedlot are likely to germinate. It is usually expressed as a percentage, e.g., an 85% germination rate indicates that about 85 out of 100 seeds will probably germinate under proper conditions. The germination rate is useful for calculating the seed requirements for a given area or desired number of plants.
 Dicot germination
The part of the plant that first emerges from the seed is the embryonic root, termed the radicle or primary root. It allows the seedling to become anchored in the ground and start absorbing water. After the root absorbs water, an embryonic shoot emerges from the seed. This shoot comprises three main parts: the cotyledons (seed leaves), the section of shoot below the cotyledons (hypocotyl), and the section of shoot above the cotyledons (epicotyl). The way the shoot emerges differs among plant groups.
In epigeous (or epigeal) germination, the hypocotyl elongates and forms a hook, pulling rather than pushing the cotyledons and apical meristem through the soil. Once it reaches the surface, it straightens and pulls the cotyledons and shoot tip of the growing seedlings into the air. Beans, tamarind, and papaya are examples of plants that germinate this way.
Another way of germination is hypogeous (or hypogeal), where the epicotyl elongates and forms the hook. In this type of germination, the cotyledons stay underground where they eventually decompose. Peas, for example, germinate this way.
In monocot seeds, the embryo’s radicle and cotyledon are covered by a coleorhiza and coleoptile, respectively. The coleorhiza is the first part to grow out of the seed, followed by the radicle. The coleoptile is then pushed up through the ground until it reaches the surface. There, it stops elongating and the first leaves emerge.
While not a class of germination, precocious germination refers to seed germination before the fruit has released seed. The seeds of the green apple commonly germinate in this manner.
 Pollen germination
Another germination event during the life cycle of gymnosperms and flowering plants is the germination of a pollen grain after pollination. Like seeds, pollen grains are severely dehydrated before being released to facilitate their dispersal from one plant to another. They consist of a protective coat containing several cells (up to 8 in gymnosperms, 2-3 in flowering plants). One of these cells is a tube cell. Once the pollen grain lands on the stigma of a receptive flower (or a female cone in gymnosperms), it takes up water and germinates. Pollen germination is facilitated by hydration on the stigma, as well as by the structure and physiology of the stigma and style. Pollen can also be induced to germinate in vitro (in a petri dish or test tube).
During germination, the tube cell elongates into a pollen tube. In the flower, the pollen tube then grows towards the ovule where it discharges the sperm produced in the pollen grain for fertilization. The germinated pollen grain with its two sperm cells is the mature male microgametophyte of these plants.
Since most plants carry both male and female reproductive organs in their flowers, there is a high risk of self-pollination and thus inbreeding. Some plants use the control of pollen germination as a way to prevent this self-pollination. Germination and growth of the pollen tube involve molecular signaling between stigma and pollen. In self-incompatibility in plants, the stigma of certain plants can molecularly recognize pollen from the same plant and prevent it from germinating. Spore germination
Conidia are asexual reproductive (reproduction without the fusing of gametes) spores of fungi which germinate under specific conditions. A variety of cells can be formed from the germinating conidia. The most common are germ tubes which grow and develop into hyphae. Another type of cell is a conidial anastomosis tube (CAT); these differ from germ tubes in that they are thinner, shorter, lack branches, exhibit determinate growth and home toward each other. Each cell is of a tubular shape, but the conidial anastomosis tube forms a bridge that allows fusion between conidia.
In resting spores, germination that involves cracking the thick cell wall of the dormant spore. For example, in zygomycetes the thick-walled zygosporangium cracks open and the zygospore inside gives rise to the emerging sporangiophore. In slime molds, germination refers to the emergence of amoeboid cells from the hardened spore. After cracking the spore coat, further development involves cell division, but not necessarily the development of a multicellular organism (for example in the free-living amoebas of slime molds).
Ferns and mosses
In plants such as bryophytes, ferns, and a few others, spores germinate into independent gametophytes. In the bryophytes (e.g., mosses and liverworts), spores germinate into protonemata, similar to fungal hyphae, from which the gametophyte grows. In ferns, the gametophytes are small, heart-shaped prothalli that can often be found underneath a spore-shedding adult plant.