When does germination start

Mesocotyl elongation depends upon energy reserves in the seed. Seedlings often fail with deep seed placement due to inability of the mesocotyl to raise the coleoptile to the soil surface. In this event the leaves may unfurl beneath the soil crust resulting in seedling death.

With exposure to light, seedling leaves begin to supply energy through the process of photosynthesis. At this point the seedling becomes independent of the seed for its food supply. The primary root, together with the closely associated seminal roots, constitute a root system capable of temporarily supplying water and inorganic nutrients to the seedling.

These roots function until adventitious roots, arising from crown tissue, form the permanent root system. The more hairy adventitious roots permeate a large volume of soil and are more efficient than the primary, seminal root system. Seedling growth and development during germination is totally dependent on energy reserves stored in the seed. Thus, with deep seed placement, the coleoptile may fail to break through the soil surface. In this event, the first true leaf, as yet contained in the coleoptile, will likely unfurl beneath the soil surface.

The leaf, without the aid of the coleoptile, is unable to penetrate the soil surface. Failure of the coleoptile to reach the soil surface is due chiefly to insufficient energy reserves to support mesocotyl elongation. The combined forces associated with mesocotyl elongation and coleoptile growth are normally sufficient to break through the soil crust. You can control temperature to control plant height.

Cooler temperatures generally slow down growth, and warmer ones speed up growth. It is still critical to maintain good air circulation and sufficient moisture. Generally, watering should be deeper to accommodate developing root systems. You may need to use different wand or hose heads to water seeds and seedlings because each use different amounts of water.

Remember to carefully monitor and water the plants at the edges of flats. They dry out faster than those in the middle. However, overwatering can increase the probability of plants developing damping off.

This final step before seedlings are planted in the field gradually exposes them to the conditions they will have in the field. This process stimulates the plants to accumulate carbohydrate and nutrient reserves and strong cell walls by exposing the plants to day and night temperature fluctuations, increased air movement and wind, reduced watering, and full light. Hardening off transplants is important, especially if they are to be planted under stressful early season conditions.

Most transplants may be hardened off by reducing the temperature in the greenhouse through ventilation. Reduced watering will also provide some hardening effect. Do not let plants wilt excessively. Do not harden off transplants by reducing fertilizer application, as this often results in stunted plants that do not establish well in the field. Some growers will put plants outside for days prior to planting. This allows the plant to become acclimated to outside conditions while still in the flat.

Plants hardened off in this manner often have improved field performance as compared to those planted directly from the greenhouse Garton, Sikkema, Tomecek The National Organic Standards require that producers use organically grown seeds, annual seedlings, and planting stock. Nonorganically produced, untreated seeds and planting stock may be used to produce an organic crop when an equivalent organically produced variety is not commercially available.

There is no allowance for seed treated with prohibited materials. Captan, thimet, and similar chemical fungicides are not on the national list and are not permitted. Please take this seriously. If your seed is covered in a pink or orange powder, it is probably prohibited. We may not be able to certify your crop if you use seed treated with prohibited materials. The first step is to determine whether an equivalent organically produced variety is available.

By equivalent variety, look for comparable growing habits, days to maturity, insect and disease resistance, flavor, and other important qualities. If a suitable organic equivalent variety is not available, document where you tried to look for organic seed, as that is important for your certification records. Once you have found a source for a specific equivalent organic seed, the next step in determining commercial availability is to see if it is of the appropriate form, quality, and quantity.

Compliance is reviewed in the context of the organic system plan, which is verified during the annual inspection. A pattern of inadequate documentation and lack of good faith effort to obtain organically grown seeds and planting stock may be considered noncompliance and might result in Pennsylvania Certified Organic requiring prior approval regarding commercial availability issues in future planting cycles.

Listed below are a number of sources for organic seed provided by Pennsylvania Certified Organic For a more complete listing including forage, field crop, and cover crop seed and transplants, go to the Pennsylvania Certified Organic website. Fred C. Gloeckner and Co. Gardens Alive! Garton, R. Sikkema, and E. Kemble, J. Alabama Cooperative Extension, Mackean, D. Maynard, D. Knott's Handbook for Vegetable Growers.

Hoboken, N. Miles, A. Pennsylvania Certified Organic. Pennsylvania Heirloom Seed Savers Club. Raven, P. Ray, and S. Biology of Plants. New York: W. Freeman, Seed Technology Educational Programs. Prepared by S.

Let's Stay Connected. By entering your email, you consent to receive communications from Penn State Extension. View our privacy policy. Thank you for your submission! Home Seed and Seedling Biology. Teachers—download lesson plans to use in your classroom! Starting to Grow What does the word "germinate" mean? To germinate means to start to grow. What is a nutrient? Nutrients are substances that living things need to grow.