University of Illinois Extension

Growing Transplants

Starting Plants at Home

Get a head start on your garden by planting frost-susceptible vegetables indoors. The seedlings can be transplanted into the garden when weather permits.

Vegetables which take longer to grow such as tomatoes, peppers, and eggplants will be ready to harvest sooner. This will extend your harvest season. Cool-season crops such as cabbage, Brussels sprouts and broccoli will be ready to pick before the hot weather arrives.

Growing your own transplants allows you to grow varieties that may not be available in local stores.

Check with your county Extension office for varieties recommended for Illinois. Seeds left over from last year may not be as viable unless they were stored properly. Seed saved from hybrid plants and planted will not produce the same hybrid plant that was planted the previous season.

Use Soil or Growing Mixes

Garden stores carry soilless growing mixes, germinating mixes, potting soils, peat cubes and compressed pellets. These are all excellent material to use when starting seeds indoor.

Consider getting one of the many mixes on the market as they are properly formulated and free of diseases and insect pests.

Adapt Containers for Plants

Seeds may be planted in peat pots, paper cups, clay pots, trays or plastic egg cartons. Punch a hole in the bottom of each compartment for drainage.

Used clay or plastic containers may be sterilized by soaking overnight in a solution of one part bleach to nine parts water. Rinse well before using.

Muskmelon and watermelon seeds should be planted in peat pots. These containers can be planted in the garden during transplanting. Peat pots are necessary since muskmelons and watermelons do not tolerate root disturbance.

Get Ready, Get Set.... Plant!

In moist soil plant two or three seeds per compartment at the depth recommended on the seed packet. After planting the seeds, water lightly. Water the plants as they grow but avoid overwatering.

Eggplants, peppers, muskmelons and watermelons should be kept in 80 to 90 degree temperatures for germination.

Other vegetable seeds will germinate at 60 to 80 degrees. Seedlings should be grown at 60 degrees at night and 70 to 75 degrees in the day.

Planting Dates for Chicago

Vegetable Plant Seeds Indoors Transplant Into Garden
Broccoli* March 10 - March 25 April 15 - May 10
Cabbage* March 25 - April 5 May 1 - May 25
Cauliflower* March 25 - April 5 May 1 - May 25
Eggplant April 5 - April 20 May 20 - June 10
Herbs April 1 - April 15 May 1 - June 10
Lettuce March 25 - April 5 May 1 - May 25
Muskmelon April 25 - May 5 May 20 - June 15
Pepper April 5 - April 20 May 20 - June 10
Tomato April 20 - May 1 May 20 - June 15
Watermelon April 25 - May 5 May 20 - June 15

*For fall gardens, these vegetables may be seeded in June in a small section of the garden and transplanted to their final location from July 1 to July 15. These plants also may be seeded and thinned in June at their final location.

Thinning Transplants

When seedlings emerge, thin to one per pot by pinching off or carefully pulling out excess plants. Thinning is not necessary when growing and transplanting muskmelons and watermelons.

Shedding Light on Transplants

Seedlings should be placed in a south or southwest window. A cool white fluorescent light or grow-light can be placed 6 inches above plants for a total of 14 to 16 hours of light a day.

Soil or growing medium should be fertile enough to sustain the plants for the first 3 or 4 weeks. If the nutrients are not adequate, plant color becomes a light or yellowish green. Use a solution made with fertilizer (10-50-10, 20-20-20, 18-12-6, etc.) at rates of one tablespoon per gallon of water. Apply once a week.

From Pots to Lots

Before seedlings are transplanted outdoors, they should be gradually hardened by exposing them to outside conditions for a few days before transplanting. Place plants outdoors a few hours each day, extending the period as planting time approaches.

If you cannot provide good conditions for growing transplants, shorten their growing time indoors and transplant younger, smaller plants in the garden. They are preferable to tall, spindling plants.