Here's How To...

Grow Your Own Starts

MSU photo by Stephen Hunts Starting your own plants from seed can give you a wider choice of cultivars than what you can often find as transplants at the local garden center. It also ensures that you will have healthy plants at the right time to set out.

If you want the very latest types of plants or want to try growing heirloom varieties, you usually have to get the seed from mail-order sources. 

Once you have the seeds in hand, however, you have to get them to germinate and grow in order to have useable transplants for the garden.  And this is where many gardeners face frustration.  Sometimes the seed fails to germinate or, once germinated, it doesn't grow as it should, resulting in poor quality transplants.

Growing plants from seed is not complicated if you know a few basic seed germination tips.

Testing Viability

Many seeds retain their viability for several years if stored correctly. There's a simple test called the "rolled towel" or "rag doll" test that, though simple, is used by the pros.

Place a known quantity of seeds on a paper towel. For example, use 10 for large seeds such as squash and beans or 25 for smaller seeds like cabbage. Fold the towel around the seeds, moisten it and squeeze out the excess water. This is your "rag doll". Place the rag doll in a jar or plastic bag. Loosely cover the jar or bag, and in about 10 days, count how many seeds germinated. If 75 to 100 percent germinate, plant as you normally would. If 50 percent germinate, plant the seeds twice as thickly as recommended. If substantially below 50 percent, toss the old seeds and head for the local garden center.

Good Starts

Short season crops, like radish, spinach, peas and beans, don't need extra time to mature and so are rarely transplanted.

Beets, broccoli, Brussels sprouts, cabbage, cauliflower, chard, kale, lettuce, parsley and tomato benefit from a longer season, reestablish easily and are good candidates for transplanting.

Celery, eggplant, onion and peppers also need a little longer season, but have more difficulty establishing a new root system after transplanting. Transplant these, but try not to disturb the root system much.

Sweet corn, cucumber, muskmelon, summer squash (including zucchini) and watermelon regenerate damaged roots slowly. Grow them in individual containers such as peat pots that can be set into the ground without disturbing the roots. Set the transplanted pot with the rim below the soil level to prevent water from being wicked up and away from the roots.
  • As a general rule, try not to disturb the roots of any transplant more than necessary.
The time it takes to grow a transplant depends upon the species, growing temperature, and how large a transplant you want. Most vegetable transplants should be stocky and about six inches tall. Taller plants are more apt to bend or break when set outside.
  • Seedlings and transplants grow better with night temperatures about 5 to 10 degrees cooler than day temperatures, though we don't completely understand why. This can be difficult to do in the home, but try it if you have the equipment.

Keep daytime temperature for tomatoes, peppers, eggplants and the vine crops at about 75 degrees and the night time temperatures about 65 degrees.

Cabbage, cauliflower, broccoli, and Brussels sprouts do better with daytime temperatures at about 68 degrees and nighttime temperatures at about 58 degrees. If you have no easy way to control temperatures, then aim for the middle of these temperature ranges.

When To Plant

Some gardeners pick dates at random when sowing seed indoors. This often results in very tall, overgrown, poor-quality seedlings because they were sown too early. 

Sowing schedules are based upon knowing how long it takes to produce a useable transplant from seed (number of weeks) and when you can safely plant the resulting tr
ansplants outdoors (based upon frost-free dates for your area). For instance, eggplant and pepper seeds require 8 to 10 weeks, while tomato, cabbage and brassicas need 6 to 8 weeks, and lettuce, melons and cucumber about 4 weeks.

For example, zinnias or tomatoes take about four to five weeks to produce useable transplants for the garden from seed.  They are also tender plants, preferring to be placed outdoors after the frost- free date.  If your frost-free date is May 15 and it takes four to five weeks to grow transplants, the seed needs to be sown between April 5 and 12 (four to five weeks ahead of the frost-free date).  

Eggplant and pepper seeds require 8 to 10 weeks, while tomato, cabbage and brassicas need 6 to 8 weeks, and lettuce, melons and cucumber about 4 weeks.

Sowing dates for various types of seed can be found in books and catalogs, or from your
local County Extension office. Knowing the number of weeks of growing time and whether the plant is a hardy, half-hardy or tender plant will help guide you on proper sowing times.

Starting Starts

When assembling seed-starting materials, remember that the container needs to have drainage holes. You can use just about anything for a growing container, but be sure it's clean.
If you recycle and use old nursery flats or cell packs, make sure they are washed clean with a 10 percent bleach solution (one part bleach and nine parts water). 

The germination medium needs to be sterile and well drained, yet retain some moisture for germination and be well aerated. 

Once your container is filled with the germinmation medium, place the container in a shallow tray filled with water. This allows the medium to be pre-moistened by drawing water up from below.  Once the surface is moist, remove the container from the tray and sow the seed.  Cover seed lightly with media.

The best germination is achieved when the media stays uniformly moist and warm. Cover the container with a piece of plastic or insert the container into a plastic storage bag and set it so it receives some type of bottom heat to keep the medium at about 70 to 75 degrees.
The top of the refrigerator or space in the laundry room will be fine. Light is not critical at this point for most seed.  Keep an eye on the container for both moisture and the first signs of seed germination. 

Cover your flat or pots with saran wrap and tuck somewhere warm until the seeds germinate, like the top of the refrigerator or in the laundry room.

Once they start to come up, remove the plastic covering and move the container to the brightest, sunniest spot possible with a little cooler temperature, a little less moisture, and good air circulation. These conditions result in slower growth and stockier seedlings.  Fast, soft growth is not desirable.

If suitable light is not available naturally, use cool white fluorescent lights.  Place the lights so they are about three to four inches above the tops of the plants and leave them on for 14 to16 hours per day.

First Transplant

Once seedlings can be handled easily, they should be transplanted to containers. Use similar types of potting soils to fill these containers and similar conditions of bright light, cool temperatures, moderate watering, and good air circulation. Fertilize with a general purpose liquid fertilizer at half strength.

Hardening Off

Getting the plants accustomed to the outdoors in a process called "hardening off." About two weeks before moving the plants into the outdoor garden, place the plants either in a cold frame or set them outside on the porch, patio, or balcony during sunny days and move them back inside at night when it gets cold.  With a cold frame, the sash can be lowered to protect the plants at night. Water less and gradually expose the plants to wind, intense sunlight and cold.

Source: Cheryl Moore-Gough, Montana State University Extension horticulturist; Greg Stack, University of Illinois Extension horticulture educator. (406) 994-6523

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