Next, use Table 1 above to find out when to move hardened off transplants to the outdoor garden, relative to the last frost date. Some cold tolerant seedlings, such as cabbage and broccoli, can be transplanted before the last frost date, but you should wait until a week or two after your last frost date to transplant warmth lovers like tomatoes and peppers.
Use your judgment to modify them especially transplanting dates given the actual weather and soil conditions in a particular season. Also note that these dates tell you when you can safely start planting. Some quick-maturing crops, like lettuce, can continue to be planted every few weeks in succession for an extended harvest. And many cold-tolerant crops can be planted from mid-summer through early fall, depending on the crop and your climate, for a fall harvest.
These crops include beans, beets, carrots, sweet corn, peas, radishes, and spinach. Cucumbers, melons, squash, and pumpkin plants also do not transplant readily.
They can be started early indoors if the seeds are sown in plantable, biodegradable pots, such as peat pots, so that their roots are not disturbed when they are transplanted. Starting seeds of these crops early indoors may be helpful if you garden in a part of the country with a very short growing season. But in general these crops will do best if they are grown from seeds planted directly in the garden.
Some direct-seeded crops are very cold tolerant and can be planted before the last frost date. For example, spinach seeds can go in the ground as soon as the soil is dry enough to work in. Other seeds, like those of squash and pumpkins, need to be planted when the soil is warm and all danger of frost is past, usually a week or two after the last frost date. Table 2 above gives you the timing relative to the last frost date to direct sow seeds in the garden. As you did before, translate the weeks before or after the last frost date into the specific dates for your area.
A life cycle shows how living things grow, change and reproduce themselves. Many plant life cycles include seeds.
This article describes the life cycle of flowering plants. Flowering plants produce seeds that are then dispersed from their parent. When a seed comes to rest in an appropriate place with conditions suitable to its germination, it breaks open. The embryo inside the seed starts to grow into a seedling. Roots grow down to anchor the plant in the ground.
Roots also take up water and nutrients and store food. A shoot grows skywards and develops into a stem that carries water and nutrients from the roots to the rest of the plant. The stem also supports leaves so they can collect sunlight. Leaves capture sunlight to make energy for the plant through the process of photosynthesis. When the seedling matures into an adult plant and is ready to reproduce, it develops flowers.
Flowers are special structures involved in sexual reproduction, which involves both pollination and fertilisation,. Pollination is the process by which pollen is carried by wind or animals such as insects or birds from the male part of a flower the anther to the female part the stigma of another or the same flower.
The pollen then moves from the stigma to the female ovules. Pollen has male gametes containing half the normal chromosomes for that plant. After pollination, these gametes move to the ovule, where they combine with female gametes, which also contain half the quota of chromosomes.
In the greenhouse, one way to achieve rapid, uniform germination is to use germination mats under the trays. These mats allow you to set the temperature according to seed requirements.
Make sure you maintain optimal temperatures for your crop see Table 1. Providing good air circulation during germination and early seedling growing will help to control diseases in this early stage. We cannot control conditions in the field like we can in the greenhouse, but we can still take steps to make sure that seeds planted directly into the field germinate uniformly. A fine-textured seed bed provides good growing conditions, ample seed-to-soil contact, and the ability to plant to a uniform depth.
Planting when the soil temperatures are near optimum will hasten germination and emergence of the seedlings. Sometimes in the rush of spring planting, seeds are sown in soils that are too cold. This can result in slow germination, weakened and diseased seedlings, and even plant death.
It is much better to delay planting until soils warm up. The optimal temperature for growing seedlings may be different from optimal germination temperatures.
Table 2 shows the range of day and night temperatures that are best for growing seedlings in a greenhouse, where temperatures can be controlled. Cooler temperatures generally slow down growth, and warmer ones speed up seedling growth. All seedlings need ample light to grow.
If light levels are low or if seedlings are too crowded as they grow, the stems will stretch as the plants seek more light, resulting in weak, "leggy" transplants.
Consider supplemental lighting if greenhouse light levels are low. The length of time that seedlings need to grow in the greenhouse before they are big enough to transplant into the field varies by crop. Tomato and pepper seedlings may take five to seven weeks to produce, while cucumbers and squash are ready to transplant after three to four weeks in the greenhouse.
But all transplants need to be hardened off before going from the greenhouse out to the field, or they will be damaged by the harsher conditions. To harden off seedlings, gradually expose them to conditions they will have in the field. Plants may show some signs of wilting, but do not let plants wilt excessively.
After a day or two, weather permitting, set the trays outside of the greenhouse for five to seven days prior to planting. If it is very hot and sunny, provide some shade for the seedlings for the first day or two. Plants that are hardened off in this manner will be better able to tolerate transplanting, and continue to grow in the field uninterrupted.
For more information, see " Seed and Seedling Biology ". 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 Understanding Seeds and Seedling Biology. Understanding Seeds and Seedling Biology. Photo: Seedling, U. Department of Agriculture, Flickr. Choosing the Right Seed Few decisions are more important to successful vegetable production than choosing the right seed.
The Right Environment to Germinate All fully developed seeds contain an embryo and, in most plant species, a store of food reserves, wrapped in a seed coat.
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