By: Sandy Feather ©2009
Penn State Extension
Q. I am starting vegetable transplants for the first time and wondered when I should start my different veggies. How long should I provide my vegetable seedlings with artificial indoor light each day?
A. The most common mistake that gardeners make when starting their own transplants is starting them too early. Smaller, stocky plants that have not started to bloom and/or set fruit will adapt to the garden more easily than leggy transplants that already have small fruits hanging on them. They have an opportunity to develop a more extensive root system before carrying the added burden of fruit.
Cool season crops are those that can tolerate a light frost, but are intolerant of summer heat. They are usually planted out in the garden in from late March to mid-April, depending where you live in Allegheny County. The northern suburbs stay cold longer than the city and southern areas. Cole crops such as broccoli, Brussels sprouts, cabbage, cauliflower, kohlrabi, pak choi and kale should be started indoors six to eight weeks before transplanting them into the garden. Start them indoors from mid-February to early March. Head lettuce can be started indoors three to four weeks before moving the transplants into the garden. Leaf lettuce is best direct seeded right into the garden, as are root crops such as carrots and potatoes and legumes such as peas.
Warm season crops are those that are intolerant of frost. They are usually planted out in the garden in late May. Tomatoes, peppers and eggplants should be started indoors six to eight weeks (nine for peppers due to their long germination time) before transplanting them into the garden. Start them indoors from early to mid-April. Vine crops such as cucumbers, squash, melons and gourds can be started indoors three to four weeks before transplanting them into the garden. They can also be direct-seeded into the garden. Other warm season crops that should be direct-seeded into the garden include beans and corn.
Fluorescent lights should run for 16 hours a day. Keep them four to six inches above the transplants.
Be sure to harden your transplants off before moving them to the garden permanently. Your transplants can be damaged by strong sun, wind and colder temperatures than they are accustomed to if you move them into the garden abruptly.
Buttercrunch Lettuce seedlings
"Hardening off" is the gradual process of acclimating them to life outdoors over a seven to ten day period. Start by allowing them to dry out a little more in between waterings, but never to the point of wilting, and stop fertilizing them. Find a sheltered spot where they can be exposed to morning sun, but where they are protected from the wind and hot afternoon sun. Start on a mild day, and put them out for two to three hours. Leave them out an hour or two longer the next day, then an hour or two longer the next, until they are out all day. Keep an eye on the weather and move them back indoors if a late frost threatens. You should also plan to harden off purchased transplants since many garden centers do not have the space or time to harden them off before they are sold.