Growing plants from seed can seem a little thankless if you've ever tried only to end up with scrawny, leggy plants that bear no resemblance to the large lush plants at the nursery. If you want to recreate the thrill you enjoyed as a seven-year-old with the nasturtium seeds in the paper cup on the window sill of your second grade class room, take heart.
Soil, water, light, and good seed. That's it, generally speaking.
The soil needs to be a good quality seed mix that you can buy ready to go or you make yourself. The soil should consist of garden loam, clean sharp sand, and peat moss, humus, or leaf mold in equal parts. The soil itself needs to be thoroughly dampened but not soggy. The container should drain well. Some gardeners use a layer of gravel with a thin layer of sphagnum moss topped with the soil. The soil can be put into seed trays or pots that have been sterilized and soaked.
During the course of germination, seeds need to be kept uniformly moist and must not be allowed to dry out. At the same time, they should not be too wet.
The trays may need bright light, but should not sit in direct sunlight, which can burn small plants. A southern exposure, just out of direct light, is often ideal. Some seeds need darkness to germinate, however, so read the seed packet for specific instructions.
The temperature for germination should be about 60–70 degrees. Germination mats are helpful, especially if you tend to be on the frugal side where heat is concerned, but you can set the trays anywhere the temperature is in that range. Sometimes the top of the refrigerator works. (This may also be a favorite location the cat likes to sleep.) Again read the specific instructions for the seeds you've selected.
High quality, fresh seeds from reputable seed producers have the best rates of germination. Cover with fine soil three times the diameter of the seed.
Various seeds require different handling. Some germinate in the dark; others need to be scarified (i.e. roughing up or pricking seed coats). Still others need to be presoaked. Read the seed packet for further direction.
Seed leaves (cotyledons) are the first leaves a young plant sends up and they all look more or less the same except for size. The true leaves develop next and at that point you'll be able to distinguish between your tomatoes and the thyme.
The warmth needed for germination is no longer required. Dropping the temperature to between 50 and 60 degrees once the seed leaves appear forces the plants to become more stocky and vigorous.
Seedlings in a window need to be turned every day to prevent them from bending.
Even moisture continues to be critical. Delicate seedlings can be sprayed or watered with a bulb syringe using room temperature water. Don't allow them to get soggy though. Water in the morning, but let them go to sleep dry.
As they grow, thin by removing weaker plants. Don't cut or break them off; pull them gently from the soil.
Transplanting strengthens some plants and weakens others. Find out which category your seedlings fall into then act accordingly. Use a teaspoon or fork to lift from the soil. Place in a prepared container and firm soil carefully about the roots. Don't plant too loosely. Don't be afraid to transplant from trays to small pots while indoors.
Once the true leaves emerge, you can provide plant food. A diluted, high-quality organic fertilizer applied once a week encourages healthy development of young plants. If you plan to transplant, don't fertilize until you've moved the seedlings.
Acclimate your seedlings for life outside by hardening them off. Tender young plants must be protected from wind, strong light, and cooler temperatures. Place them in an area where they will receive dappled shade and a few hours of sun a day, increasing exposure to sun a little each day. If it is still very cold at night they should be moved indoors. Continue keeping them evenly moist. It takes about two weeks to condition your plants.
At this stage, start watching for slugs and bugs. Slugs in particular are notorious for annihilating small seedlings. Yum. If you see them, kill 'em. Show no remorse. The only good slug is a dead slug.
Some plants benefit from transplanting; others don't. Read the seed packets because they will often tell you what works and what doesn't. No seed packet can replace a good gardening book and experience.
Don't rush to transplant seedlings into the garden. If your enthusiasm got in the way of planning, now is the time to sit down and plan out which plants go where. Consider what does well with other plants. Some plants, especially vegetables, will not produce well if planted near incompatible plants or in the soil of an unloved plant from the previous season. Color combinations can make a difference too. If your seedlings require staking or trellises, it's best to have those in place before you plant.
To transplant, prepare containers and soil. Terracotta pots should be soaked ahead of time. Soil should be moistened uniformly, but emain workable. It should form a ball but readily fall apart. (If it's super sticky, it probably has too much clay. Amend with compost and some sand for better drainage.) If you are transplanting from seed trays, gently pull the young plants apart and place gently in a prepared hole. If you've transplanted your seedlings from seed tray to peat pots, you can plant your starts directly into the ground without disturbing the roots. Firm soil around the stems or pots.
It takes a few days for plants to become accustomed to their new environment. If you protect them from environmental stresses and hungry bugs and slugs, you should start to see them take off in about a week as long as the weather cooperates. Timing is important, but even the most experienced gardeners are only able to do their best guessing about when to transplant. A very wet or dry spring can throw off your entire time table.
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