If you are staring at all of the seed packets spread out on your kitchen table and wondering which ones you should start indoors, your first thought should be which seeds are amenable to the transplant process.
Many kinds of vegetables can be satisfactorily transplanted. For best results with all the cucurbits - cucumber, squash, watermelon, and muskmelon - plant the seed in a container that will be set in the garden without disturbing the plant's root system, such as peat pots. (When planting, be sure to remove the bottom of the container to ease the roots' progress into the soil.) The Cole crops cabbage, cauliflower, Brussels sprouts, and broccoli can be transplanted either in containers or bare-root. Other vegetables such as lettuce, onion, pepper, eggplant, and tomato can also be transplanted bare-root. However, it is also best if all are grown in a type of container that will allow transplanting with the root ball essentially intact.
Most plant growers "harden off" vegetable transplants before planting them in the garden. This is done by using one or all of the following: reducing growing temperature, withholding water, and increasing light intensity. The most common procedure is placing the plants outside during favorable weather in the last week or two before setting in the garden. The plants remain outside for only an hour or so to start and are not exposed to direct sunlight. Each time they are out, the time and sunlight exposure is extended, until the plants remain outside overnight. They are then ready for transplanting in your garden.
Celery plant is one of many garden vegetables that can be started indoors.
Do the transplanting on a cloudy day, provide the transplants with some shade, or wait until late in the day to do the job. Dig a hole large enough to hold ALL the roots of the transplants. Spread the roots so each has plenty of space; NEVER curl a root around in the hole. Do NOT pull the plant out of its container by the stem. Gently ease the plant out of the pot by either tipping sideways or rolling the pot if the plant is root bound and gently loosening the soil around the walls of the container until it comes out easily. Peat pots can be placed directly into the ground after the bottom is removed. Make sure that the peat pot is completely covered with soil or it will act as an air wick and dry out the plant. Carefully transfer the plant and any soil in which it has been growing into the prepared hole. With the plant in place, carefully cover roots and some stem with soil. Firm this soil around the plant to avoid air pockets around the roots. With your hand, form a slight cup-shaped depression around the plant and fill it with water or manure tea right away. Manure tea is made by putting manure in a cloth bag which is then soaked in water for a few days.
Protect your transplants as soon as they are planted. Protection is the real secret to getting transplants off to the best start. The plants can have weeks of head start on unprotected plants. Heavy spring rains and chilling winds do a great amount of damage to all unprotected early season plantings and retard their growth.
Get in the habit of protecting both your seeds and transplants as soon as they are planted. Tin cans with neither top nor bottom, plastic jugs with bottoms cutout and caps removed or anything readily available can be used for protection. Metal fencing can be bent into a desired shape and covered with clear plastic or row cover. You can form tunnels, square boxes for sections of wide rows, or cylinders for individual plants. Close the tops or ends during the early season and you'll have a miniature greenhouse, but don't forget them during a warm spell or your greenhouse will turn into an oven. Your seeds and plants will reap the benefits of constant moisture and heat, and will be protected from damaging winds, rain, and sudden changes in temperature. As the weather warms, gradually open the tops or ends, or even remove if the protection is no longer necessary.
Mary Perkins is a Master Gardener Volunteer with Cornell Cooperative Extension