Home & Garden

Starting transplants

gardening by Sally Anne Sadler, WSU Cooperative Extension
I love starting my garden from seed. In order to feel right about it, I have to grow my own transplants. Let's start with the basic materials you need.
   Seeds need water and warmth to get them to decide that now would be a good time to come out and see what the world has to offer. I use a recycled, plastic seed flat with plenty of drainage holes and a stiff plastic mesh flat underneath it to give added support. Adequate drainage is important.
   I have also used salad-bar containers–clear styrene "clam shell" containers from the supermarket. They work well, if you don't over-plant them. Make sure you put holes in the bottom and top (for the water to drain out and air to get in). You can also start seeds in 4-inch plastic pots or terra cotta pots, but they tend to take up more room and are awkward, if you have more than a few.
   When you have chosen the pots or flats, clean them up. It is important to wash them before you fill them with soil, in case last year's seedlings or soil carried disease. You can clean them with a mild bleach-water solution.
   Now a seedling soil mix. There are many ways of doing this. Light, screened compost mixed with vermiculite or sand is a good option if you want to make it yourself. Though peat moss is very light, it also repels water when it dries out, is nutrient poor, and is a non-renewable resource, so unless you have that on hand, you might want to consider alternatives. You can purchase potting soil from a local nursery. Just make sure it is very light and airy, while still able to hold moisture.
   Many plants can be planted fairly close together in a flat, tomatoes included. You just want to make sure to get them into a larger container before the roots get so developed they are cramped on the bottom of the tray. If you allow the small plant to get rootbound, many plants will begin to think "time to flower," and stop growing and go to seed. This is decidedly not what you want from a 4-inch-high plant. You also want the seedlings far enough apart so air can circulate between each plant.
   Many seeds will germinate without much heat, but they tend to do much better with a bit of added warmth. I put a stack of newspapers on top of the refrigerator and place the flat up there. A friend suggested chopsticks on their sides to assure some air flow between the flat and the newspapers. It is warm enough up there for my bread to rise in an otherwise cool apartment. Other suggestions are a heating pad, covered with paper and then plastic, or a heater from an old waterbed under the flat. I haven't tried this myself, but they have a thermostat and have been spotted at places like Value Village for a song. If you try a setup like this, check it carefully after the first couple of hours. The bottom of your flat or seed tray should feel warm, not very warm and certainly not hot.
   Since I start my seeds far away from natural light, I have to make sure they get plenty of artificial light. There are two ways of supplying enough light. Well, three, but I am too cheap to buy a grow-light, so now we are back to two. I have hung a regular shop light by a chain and kept it about three inches above the flat for 12 or so hours a day, or I have used an incandescent light. The problem with the latter is the little guys on the edges of the flat show off their heliotropic powers and bend toward the light. Incandescent lights are also hot, so it's hard to keep them as close to the plants.
   Reflecting the light back to the area where the flat is with a sheet of mylar or aluminum foil is a horrendously ugly, though effective, way to make the light more efficient. On sunny days, I supplement the light by carrying the flat to the kitchen table. (It's level with our only south-facing window.) They seem pretty happy about that.
   It's important to feed your seedlings once they have germinated. I feed them one-half the recommended strength of fish emulsion when the plants have two true leaves. The first two leaves of most seedlings are "seed leaves," the next two to emerge are "true" leaves. (Corn and onions are the exception, in that they have a single seed leaf.) Once the tiny plants have true leaves, I start feeding them about once a week. If they are not going out fairly soon, this is also the stage at which they can be transplanted to individual pots.
   Grow your plants inside until the oustide temperatures allows you to plant them out. Heat-loving plants, like tomatoes and peppers, need tender loving care longer than cole crops, like collard greens and broccoli. We can usually set our cole crops and lettuces in March and April. Tomatoes and peppers want to be coddled until early to mid-May. Tomatoes will be about six or seven weeks old, and lettuces about three weeks before you want to start setting them out.
   Now that you have nice, stocky transplants, you need to harden them off. They must get prepared for the harsh realities of the real world, where temperatures fluctuate, rain falls and wind blows. Hardening off seedlings takes some time. To do this, a week or two before you want to plant out the vegetables, set them out during the day and take them in at night. It is best to start by placing them in a very protected area. After a few days, full sun and a little breeze can be good. It really does help to strengthen the stems. By the end of the week, you can leave them out on mild nights. Once you've done that a while, you can set them out in the garden and only worry about extra protection on really cold nights.
   Making a simple cold frame out of recycled milk jugs over the new plants or constructing a plastic tent will help generate extra heat during the days and increase the night-time temperature. Floating row covers will also offer a bit of protection. This is especially important for heat-loving vegetables.
   There are nearly infinite ways to extend the season or preserve the little heat we get in the Pacific Northwest. Consider using one of these when you first set out your plants in the garden.
   For starting and planting dates, send a self-addressed stamped envelope to WSU Cooperative Extension, King; 506 2nd Ave., Suite 612; Seattle, WA 98104. Ask for "Community Horticulture Factsheet #8."

Visit WSU's Agriculture Site on the World-Wide Web at http://www.cahe.wsu.edu.