Growing Vegetables from Seed
Seeds are sown either directly into the ground or in flats to be transplanted later. What follows is a brief description of the process of growing from seed. Here are several good pamphlets with more details:
- Propagating Plants from Seed - A thorough description of growing vegetables from seed, published by Washington State University.
- Scheduling Vegetable Plantings for Continuous Harvest - This publication helps growers plan planting times and succession planting, by providing soil temperature germination ranges and other information of assistance to market gardeners.
Sowing seeds in pots or flats. Seeds grown in flats will get a head start on the season; once they are planted in the field they’ll have a head start on weeds and outcompete pests; they can be planted out to the correct spacing, and growing in flats makes watering easier and saves a lot of garden space while you’re waiting for the plants to germinate and size up. Seeds in flats need a warm, sunny place to grow. A sunny windowsill will work, but plants will often become long and “leggy”, from stretching towards the sun. A cold frame or greenhouse is best. See this article on building a cold frame. You can build a quick cold frame with straw bales and old windows by arranging the bales into a U shape and placing the window over the top. The open end prevents the plants from overheating, though you’ll still need to check them on sunny days.
Containers - There is a wide variety of containers available for growing seeds, many can be had for free from nurseries or farms, but be sure to ask if there are any diseases or pests in or on the containers – If you do not already have the brown garden snail or garden slugs then be cautious about bringing potted plants and used seedling flats and containers into your garden as this is the most common way the snails are spread. A container should be at least 3 inches deep to accommodate good root growth. Make sure containers have slits or holes in the bottom so that water can drain freely. Seed flats are large trays with continuous soil, six packs are divided into individuals cells.
Potting Soil – Potting soil is available at any garden supply store, and has the advantage of having the right nutrients and being weed free. You can also make your own potting soil by mixing fertile garden soil with good compost and some sand if necessary. If the compost is not rich enough you’ll need to add a nitrogen source such as well composted manure, be careful not to use too much or the young seedlings will “burn”. Make sure you fill your flats all the way to the top and tap the container, the soil will settle and you want it as full as possible.
Sowing Seeds – Follow the instructions on the seed packet. Rule of thumb is to plant seeds to a depth that is twice their width. For small seeds you can place them and then cover with potting soil, plant larger seeds into mini furrows or press them into the soil. Once planted, seeds need to be kept moist, but not too wet. The number one reason for failure is plants drying out, so if possible put your cold frame or greenhouse in a well-travelled place so that you’ll remember to check your plants often. A light watering from a can or garden spray nozzle will prevent compaction, don’t water with a heavy spray directly into the flats as you’ll end up with hard, compacted soil. Avoid watering too late in the day to prevent molds and “damping off”, a Phytopthora fungus, that can develop in over-watered seed flats and results in seedlings wilting at the soil level.
Transplanting Seedlings – Seedlings grown in six packs can often be transplanted directly into the bed. Seedlings planted at tight spacing in flats will need to be “pricked out” and transplanted into larger containers such as 4 x 4 inch pots. Do this when plants have developed at least two to four true leaves (don’t count the very first leaves that emerge, the cotyledons, these are not true leaves). Plants that benefit from potting, include tomatoes, peppers, eggplant, basil and the brassica family crops - broccoli, cabbage, cauliflower, kale, collards, etc.