Seeds require a certain temperature in order to germinate. Each plant has a specific optimum and a range within which germination will occur. The closer the temperature is to optimum, the quicker germination will occur. Most seeds germinate when the soil temperature is between 68° and 86°F.
Temperature influences the moisture content, hormone function, and enzyme activity that occurs during seed germination. Warm temperatures accelerate the chemical reactions in seeds and accelerate cell formation for development.
For many garden plants in fact, a soil temperature below 50°F can be a problem. With temperatures in the 40s, seeds will readily absorb water, but not start to grow.
High temperatures over 90 can kill the plant inside the seed. Was the parent plant healthy? Seeds can harbor infection from the parent plant that may prevent sprouting, however, this is not usually the case.
In most cases an interior temperature of 60-70 degrees is not warm enough for quick germination, but seeds usually will germinate eventually (lack of supplemental heat is especially detrimental to peppers and eggplants, both of which are REALLY SLOW to germinate when left at room temperature).
All seeds need water, oxygen, and proper temperature in order to germinate. Some seeds require proper light also. Some germinate better in full light while others require darkness to germinate.
Most of the seeds germinate best in dark environments. The presence of light tends to inhibit their growth. The light decomposes carbonic acid gas and expels oxygen which leads the seed to harden. These gases are key factors that promote germination.
Optimal conditions are 85°F day, 70°F night with diffuse light and high moisture. It is the policy of the University of California (UC) and the UC Division of Agriculture & Natural Resources not to engage in discrimination against or harassment of any person in any of its programs or activities.
Temperature, moisture, air, and light conditions must be correct for seeds to germinate. All seeds have optimal temperature ranges for germination (Table 1). The minimum temperature is the lowest temperature at which seeds can germinate effectively. The maximum is the highest temperature at which seeds can germinate.
Some seeds like Allium 'Purple Sensation' and Eryngium giganteum need a long period of cold-moist stratification with alternating temperatures. These are the most difficult seeds to germinate.
Most seeds will not germinate without sunlight and will perform best with 12 to 16 hours each day. Indoors, place seed containers in a sunny, south-facing window and give the container a quarter turn each day to prevent the seedlings from overreaching toward the light and developing weak, elongated stems.
Most indoor seedlings will need to be watered twice daily. Meanwhile, seedlings planted outdoors may not need as much attention. Watering your outdoor seedlings once a day or every other day may be enough, especially if it always rains in your area.
They actually prefer long nights during germination. So you can start them indoors under plastic, and remove the plastic and place them under light after they've sprouted.
Cloddy and compacted soils that are high in clay will inhibit seed germination and emergence. Soils with a lot of plant residue in the top four inches and soils that form a crust when dry may also prevent effective germination and emergence. Seeds need air and moisture to germinate.
Germination depends on several environmental factors, e.g., water, oxygen, temperature, and often light and nitrate as well. Of these, water is the most essential factor.
Factors such as oxygen, water and temperature are required for seed germination, but the light is not an essential factor amongst other factors.
Before your seedlings germinate, the easiest way to water smaller, shallowly planted seeds is with a mister or very gentle spray bottle. Using a watering can or hose without a mister can displace smaller seeds and can make it easy to over-water.
Some are quick to germinate, taking 1-2 weeks at most, such as chillies, beans, sunflowers and pumpkins. Some seeds take more like 2-4 weeks, such as mango and parsley. Others, depending on how warm/cold it is, take closer to 2 months, for example avocado.
For many years, fluorescent shop lights were the go-to seed starting bulbs for gardeners, but LEDs have quickly replaced them as the standard choice. LEDs are usually more expensive than fluorescent bulbs, but they are very energy-efficient and long-lasting.
It's official: beans, peas, and pumpkins are among the top ten easiest plants to grow from seed, according to a list created by the Home Garden Seed Association.
By soaking the seed, it enables the new growth from the inside to push through the hard shell and grow. The seeds that could benefit from a good soaking include: corn, pumpkin, beans, chard, beets, and peas. The seeds you shouldn't soak include: carrots, lettuce, radish, celery, turnips, and spinach.