A MAtter of Degrees

September 2018

Pickaway to Garden

A Matter of Degrees

By Paul Hang

My normal September columns talk about fall and the onset of cooler temperatures. With the shorter days, and the lower angle of the sun, the days and nights should be growing cooler. Just a few days ago we had the hottest days of the summer with more to come. Even tomatoes, a hot weather plant, have found it too hot and are languishing. If this is a sign of the times, and climate scientists assure us that it is, then the usual September advice will be moved to October or even November. As climate change has dealt us extreme weather events, prognostication is risky.

When is fall? When it comes to temperature it is a matter of degrees. In fall weeds are less likely to germinate, moisture is generally more abundant, cooler temperatures keep the insect populations down and most diseases don’t find conditions helpful. Notice how I qualify everything? Change is coming it’s just a matter of degrees. For plants the magic number is 50. Fifty degrees is the temperature below which most vegetative growth stops. Most seeds need at least 50 degrees to germinate. Because of the cooler temperatures the soil also retains moisture longer. All of this adds up to making fall the best time to plant cool season vegetables, shrubs, trees and to patch or start a lawn.

Of course temperature can be either the warmth of the air, or the warmth of the soil. The temperature of the air can change quickly, the temperature of the soil not so fast. Tender plants can be killed by a hard frost. Half-hardy plants can be killed by a freeze (28 degrees for more than 4 hours). Trees and shrubs and perennials are not normally killed by a freeze unless it is sustained below their normal temperature zone.

For them soil temperature is the key. Root growth continues while the soil temperature is around fifty degrees even if the air temperature is below freezing. What appears to be dormancy above ground doesn’t apply underground. When you plant perennials, spring bulbs, root crops, trees and shrubs in the fall their roots continue to grow. Some winters around here the soil temperature in the root zones never freezes. It is not unusual for the roots to continue to grow through January.

For grass, the seed will germinate as long as nighttime temperatures don’t go much below 50 degrees. Remember the soil temperature doesn’t change as quickly as the air. Sowing grass seed in prepared soil, mulching with seed free straw (cover about half the bare ground) water regularly and you can establish a fabulous lawn. This works for bare areas also. Don’t mow until the grass is established at about 4 inches height and then mow down to 3 inches.

For newly planted trees and shrubs water well and frequently until the ground freezes. This is true of all trees and shrubs if we have a dry fall. Evergreens especially should be watered generously until freeze-up. With their foliage (needles) remaining on during the winter they are susceptible to drying out.

Don’t give up on the garden or the yard. In many ways this is the best time to prepare them for next year and there is still time to plant more vegetables and flowering plants. Check out the “Things to do in the garden,” and decide which apply to you and to your “to do” obligations.

Things to do in the garden:

As plants "give up the ghost" consider removing them from the garden. If they are annuals pull them up, if perennials cut them off, unless you want their winter interest and home for overwintering pollinator eggs, larvae, pupae or cocoons. Dispose of the debris in a "hot" compost heap, bury them or put them in the trash. In the butterfly garden you will surely want to leave the host plants as they are harboring the overwintering eggs and larvae of next year’s butterflies. Those plants that you don’t want to re-seed by all means remove the seed heads before their seeds are scattered. Or, leave them for the birds. Clean up old fruit from around fruit trees.

Collect, dry, and store seeds for next year. Use only heirloom varieties, hybrids will not grow true. Harvest and cure winter squash and gourds if they are ready. Leave a two inch stem. Gourds should be finished with growth before you cut them from the vine, store indoors at 60 degrees.

September is the best time to plant grass seed whether you are re-seeding, patching or establishing a new lawn. If you only fertilize your lawn once a year, or if you have never fertilized it, fall is also the best time to do it. Cooler, wetter (usually) fall weather promotes good root growth and your grass will start out next spring healthier and ready for more vigorous growth. Want to really get your lawn in shape? Fertilize in September and then again around Thanksgiving. Labor Day and Veterans’ Day are easy to remember. Read directions for amounts.

In those areas that are not to be fall planted, plant a cover crop or “green manure” that will be turned in in the spring. Buckwheat, annual rye, sweet clover, winter barley, wheat, soybeans, alfalfa, and hairy vetch make good green manures.

Now is the time to plant spring flowering bulbs. A good rule of thumb is to plant bulbs at a depth about three times the height of the bulb. Planting irises and peonies this fall takes advantage of the warm earth. They should be planted about 2 inches deep. If your peonies haven’t bloomed well because of shade from nearby competing trees, now is a good time to move them to a sunnier place in the yard.

Watch for yellowing of gladiolus leaves. Dig the corms and hang until the tops turn brown. Then store in a cool, not freezing, well ventilated basement or garage. Do the same with caladium, cannas, and dahlias when their tops turn brown. Fall is a good time to divide Lily of the Valley, primroses, peonies, day lilies, coral-bells and bleeding heart. Adding bulb food and humus will be rewarded in the spring.

You can plant onion seed now for early green onions and bulbs. Yes, onions are bulbs. You can still plant cool season vegetables. It’s not too late to start beets, carrots, kale and lettuce, maybe even bush beans! If you have row covers, or can make them, you can have these for Thanksgiving dinner. Of course this assumes we don’t have a hard freeze and if we do you are prepared to cover the plants if it happens. If the ground temperature stays above 50 roots continue to grow. Order garlic bulbs now for planting later.

Now is a good time to test your soil. The called for amendments will have time to work their way into the soil and be available to the plants for the next growing season. Information on soil testing is available at the OSU Extension Office 740- 474-7534.