Planting from seed allows timing seedling growth for perfect transplant vigor

By Cheryl Moore-Gough

MSU Extension horticulturist

MSU\Stephen hunts Done correctly, you can have nice transplants ready for the growing season like these carried by Darcy McCune in the 2006 organic market garden class.

BOZEMAN - 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.

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.

Short season crops, like radish, spinach, peas and beans, don't need that extra time and so are rarely transplanted. Beets, broccoli, brussels sprouts, cabbage, cauliflower, chard, kale, lettuce, parsley and tomato benefit from a longer season, re-establish 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.

To determine when to start your transplants, ask your local MSU County Extension office for the right date to set plants outdoors in your area, and then count back the number of weeks you need to grow the transplants. You should never let transplants become old enough to flower or set fruit before planting them in the garden so don't be in a hurry to start your seeds. And don't be in too big a rush to set them outdoors, either. Give them a hardening period to adjust to outdoor conditions by watering less and exposing them to wind, intense sun and cold gradually.

In general, eggplant and pepper seeds require eight to 10 weeks, while tomato, cabbage and brassicas need six to eight weeks, and lettuce, melons and cucumber about four weeks. While you're at it, start flowering plants to add a bit more color to the vegetable garden - seed petunias when you seed peppers, marigolds and asters when you seed cabbage and cosmos when you plant cucumbers.

You can use just about anything for a growing container, but be sure it's clean. Wash them with hot soapy water, rinse and dip in a 10 percent chlorine bleach solution and rinse again. Your growing media needs to be clean, too. Purchase starting mix or make your own soil-less mix with 50 percent vermiculite or perlite and 50 percent fine peat moss. If you must use your garden soil, bake it at 200 degrees until the internal temperature is 180 degrees, and hold for 30 minutes. This is a stinky business, but it will kill any disease organism present. If your garden soil is high in clay, you can lighten it up by adding perlite or vermiculite.

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.

After the seeds germinate, set your plants in a sunny room or an enclosed back porch. If the light is week, supplement it or your transplants may be weak and leggy. You can use a fluorescent fixture with one cool and one warm bulb or grow-lights, which provide a full spectrum.