Tidewater Gardening - September 2012

Time for Planting!
K. Marc Teffeau

Moving into September, garden centers usually do a “Fall is for Planting” promotion for shrubs and trees. Now is the ideal time to not only plant trees and shrubs, but also for some late season vegetable gardening.
For direct-seeded vegetables like spinach, kale, collards, lettuce mixtures, carrots and beets, the National Home Garden Seed Association recommends the way to determine fall seeding dates is to first check the seed packets for the “days to maturity” number, then add 14 days to that number and subtract the sum from your average first frost date. For example, the average first frost date for Preston in Caroline County is October 25, and as late as November 18.
To find your frost date, go to the Moon Garden website at www.moongardencalendar.com/mgc/index.cfm/apps/FrostDates and type in your zip code. So... if you want to plant spinach with 40 days to harvest, and your early frost date is October 25 - 40 + 14 = 54. 54 days from October 25 is September 2. For the last couple of years we have had very mild fall temperatures, so I am also betting that I can seed a little bit later in the month and still be okay.
An interesting fact is that root vegetables like beets and carrots respond to frosty nights by becoming sweeter. Make sure to have some row cover fabric available to cover the plants if a hard frost is predicted. You could probably get away with planting broccoli and Brussels sprout transplants the first week in September if you can still find them, but be prepared to cover for frosts. As I have mentioned in previous Tidewater Gardening columns, one mild winter I was still cutting broccoli on Christmas Day!
While we are talking about the vegetable garden, a good clean-up starting in September is needed. Removing the dead and dying plants will help to reduce the overwintering stages of many plant diseases and insect pests. Disease and insect infested plants should not be put in the compost pile but should be bagged up and put in the trash.
After cleaning the garden, add the soil test recommended amount of lime and organic matter.
The final step is to protect the soil with a cover crop. Cover crops, when sown in the fall and plowed under in the spring, are valuable because they improve soil tilth and fertility as well as prevent erosion during the winter.
The most valuable cover crops are legumes, such as vetch and clover. These plants have nitrogen fixing bacteria associated with their roots that take nitrogen from the air and convert it into a form usable by the plants.
The best legume for home gardeners is hairy vetch. It is a winter annual and one of the most valuable of all soil builders. Sow the seeds in early September and plow the plants under in April.
A non-leguminous plant recommended for home gardeners is rye. Sow rye from early September through early October. Rye can be a very fast grower, however, especially in early spring. Have the lawn mower handy to cut it if it is growing too fast.
If you like peonies, both garden and tree peonies can be planted now so they will have time to become established in the soil before winter. Dig a hole 18 inches across and 18 inches deep for each tuber. Space the holes so that the plants will be at least 3 feet apart. Make sure the roots are buried only 1½ to 2 inches below ground level. Deeper planting keeps the peony from blooming.
Although peonies are very hardy, it is advisable to cover the soil with 2 to 3 inches of mulch for the first year to make sure they have protection for the winter.
September, through the first week of October, is an excellent time to repair drought damaged lawns, over-seed or start a new lawn. Weed pressure is declining; the cooler temperatures favor cool season grasses like tall fescue, red fescue and bluegrass. If you have broadleaf weed patches in the lawn, selectively treat these areas with a liquid broadleaf weed herbicide. This is a good time to control these weeds because plants will move foods from the leaves, along with the herbicide, down to their root systems.
My recommendation has been that if a spot in the yard is over 50% crabgrass or weeds, the best approach is to “Roundup” the area, wait the appropriate waiting period indicated on the label, and then till up and replant.
I think that many Maryland homeowners are still not aware of the fertilizer application laws that were passed by the Maryland General Assembly last year. You will be required to follow University of Maryland guidelines when fertilizing lawns, gardens and landscape areas.
The following provisions of the law that apply to homeowners include prohibiting application of lawn fertilizer on impervious surfaces, applying fertilizers on lawns between November 15 and March 1, and when the ground is frozen. Also, you can’t apply within 10 to 15 feet of waterways and you are restricted in the amount of phosphorus that can be applied to turf, with allowances when soil tests indicate low or medium phosphorus levels, or when the homeowner is establishing a new lawn or repairing or reestablishing a lawn.
The regulations also establish maximum application rates for total nitrogen and water soluble nitrogen. My position has always been that you soil test first before applying fertilizer. For more information on the rules and regulations, contact your county extension office.
If you have had woody plants die from drought stress this past summer, you can replant now. By planting in September your plants do not endure the stressful summer heat while trying to establish a sufficient root system.
If your landscape area is small, select diminutive cultivars of woody ornamentals. Look for Latin names that include “compacta” or “repandenus.”
If you are doing some fall landscaping, select some accent plants that will provide autumn color. Trees that turn red include dogwood, red maple, black gum, sweet gum, and red or scarlet oak. Shrubs with red fall foliage include viburnum, winged euonymus and barberry.
For established deciduous trees and shrubs in the landscape, wait for their leaves to begin to drop before fertilizing them. This signals dormancy, when no new growth will be stimulated that might not harden prior to cold temperatures. However, roots are active until soil temperatures drop below 40°, so nutrients will be taken up and used by the plants to develop a stronger root system.
Also, allow plants to finish the summer growth cycle in a normal manner. Never encourage growth with excessive pruning at this time as plants will delay their hardening process that has already begun in anticipation of winter several months ahead. New growth can be easily injured by an early freeze.
Houseplants that were growing outside should be prepared to be brought back inside. Gather them together and place them in a shady area. Check them for any signs of insects and prune and repot any that may need it. Leave them in the shade a few days to get them used to low light conditions similar to indoors. Browning leaves and leaf drop can happen in some species because of the change in light conditions and the lower humidity that is found in most homes.
If you have the tender bulbs of gladiola, dahlia and tuberous begonia in the landscape, now is the time to prepare them for winter. Carefully dig the bulbs and leave the foliage on. Put the bulbs in an airy, protected area for two to three weeks. Foliage on gladiola and dahlia can them be cut off with a sharp knife. Cut at the point where the foliage emerges from the bulb. Begonia stems should be allowed to dry until they are brittle and can be broken off from the bulbs.
And, of course, September is the time to plant flowering bulbs of daffodils, tulips and crocus for beautiful color come spring. There are plenty to select from at the garden center and nursery now. Make sure there is good drainage where you plant the bulbs. The bulb packaging will instruct you for appropriate planting depths. If you have loose bulbs, a good rule of thumb is to plant bulbs three times their height deep. That means look at the bulb’s height in inches and multiply by three. That will give you the proper depth and planting distance apart.
And don’t forget the “minor” bulbs. Minor bulbs comprise a whole group of bulbs that are often overlooked, or at least not planted in great quantities, but provide early color and unusual flowers. Minor bulbs include Alliums or “flowering onions,” Fritillaries, rock garden Iris, Eremurus, also known as Desert Candles or Foxtail Lily, Snowdrops, Grape hyacinth and Winter aconite.
Happy Gardening!