Tidewater Gardening - September 2013

Swinging Into Fall


K. Marc Teffeau

After an unusually wet summer we are now transitioning into the fall. Of course, as I write this column a month ahead, we don’t know what the hurricane season is going to bring for September and October, so more rain than normal may be on the way. Right now we seem to have enough soil moisture to carry the landscape into the fall, but if a dry period occurs you will need to consider watering needled and broad-leafed evergreen shrubs to prepare the for winter. Keep an eye on the weather forecast.
The summer lull has ended and now its time to get back to work in the landscape and garden. Make sure you stop pruning and fertilizing ornamental plants. Trees and shrubs should only be pruned at this time if they have dead, damaged or hazardous branches. Wait until after all the leaves have dropped or after the second hard frost for all other corrective and cosmetic pruning. If desired, mark branches now with string or light-colored tape for pruning after leaves fall.
If you do any pruning on spring flowering shrubs like azaleas, rhododendrons, lilacs, spirea, etc., you will be pruning out next year’s flower buds.
When examining trees in the landscape, you might find the large tents of the fall webworm at the ends of tree branches. The caterpillars have finished feeding but the large nests on the ends of branches are still visible. It is unsightly but causes little damage. They can be removed with a stick or pruned out if desired.
Also remember that evergreens, especially white pines, naturally drop their old leaves and needles in the late summer and early fall. This is not a cause for concern. Many years ago (in the last century!) when I was the county extension agent in Talbot County, I used to get many calls about this time from homeowners concerning their white pines “dying” in the landscape. This is just the normal leaf drop.
Fertilizing shrubs at this time will encourage a flush of new leaf growth that will not have time to mature and harden before the first hard frost. Again, as with the timing of pruning, wait until after the first or second hard frost to apply fertilizer. The better approach is to not fertilize until the early spring, before plants break dormancy and push out new growth. Late January through February is the best time to fertilize woody ornamentals, in my opinion.
This is still a busy time in the vegetable and herb garden. Now is a good time to propagate herbs from stem cuttings, if you want to bring some of the plants inside for winter. Check to make sure that the cuttings are insect and disease free before cutting and propagating.
Herb leaves are most intensely flavored right before the plant blooms. Snip foliage in the morning after the dew has dried and prune out the flowering parts so the nutrients going to the reproductive part of the plant can be used by the leaves. Pick herbs for drying or freezing now while they are at their peak of flavor.
September is a great time to plant garlic in the vegetable garden. Plant garlic cloves in a well-drained soil, rich in organic matter, and in full sun. The cloves should be planted with the pointed side up and set at 1 inch deep and 4 inches apart in rows that are 1 to 2 feet apart. Fall-planted garlic may not emerge until spring. If it does emerge in fall, and a heavy frost is expected, mulch tender greens for protection.
It is important that you purchase garlic cloves that are fresh and free of disease and rot problems. A number of the vegetable and seed catalogs offer many different varieties of garlic. Burpee® has a good selection.
Garlic is a relatively fuss-free crop and just needs about one inch of water every week or two. Provide plants with extra water during especially dry periods. Harvest garlic when foliage dies back. Dig the bulbs out with a pitchfork and cure them in a warm, dry place for a week, then store them in a cool, dry place.
While you are in the process of harvesting tomatoes, squash, peppers and warm-season crops, you can also plant a nice fall garden in September. When planting fall vegetables, be aware that more time will be required to bring the crop to maturity because of reduced light and ambient temperatures. Add at least 2 weeks to the “days to maturity” number on your seed packets.
Cover your fall garden crops in September with a floating row cover or cold frame to further extend the harvest period. A number of leafy greens such as kale, Chinese cabbage, spinach, lettuce and root crops such as carrots, beets, and turnips can be planted now.
If you have potatoes, dig the ones that you intend to store on a cloudy, warm day after plants begin to die back. Let the potatoes lay on the ground for a few hours before bringing inside. Potatoes should not be washed as washing increases the chance of rot in storage.
Store potatoes in a dark, cool locations (35°-40°) inside. Sweet potatoes should be harvested the same way, except that it helps to “cure” the roots for 10 to 14 days in a warm, dark location (85°). Curing helps to heal over cuts and scrapes before being stored for the winter in a cool, dry location (55°),
For winter squash it is important to cure them before storage. Place the squash in a cool, sheltered shady spot for about 1 month. Do not lay them on the ground. A simple curing table made from a mesh wire will work well. Place the squash on the table out of direct sunlight to allow the air to circulate all around the squash.
Now is the time to start bringing your houseplants back indoors for the winter. Check carefully for hitchhiking pests. If the plants have out-grown their pots, re-pot them into a larger pot, or remove them and trim back the roots.
It is important to use lightweight, well drained soil-less potting mixes. It has been a standard practice to use pebbles, stones, and shards of clay pots in the bottom of the pots. However, these materials do not need to be added to the bottoms of planting containers. This actually reduces space for root growth and, thus, plant growth.
Some houseplants will drop leaves and slow their growth as they become accustomed to low-light conditions indoors. Be careful not to over-water them during this adjustment period that may take several weeks.
Start fall clean up in the flower beds by cutting back anything that has finished blooming or is diseased. Leave the large seed heads of black-eyed Susans, coneflowers and other perennials for birds to feed on over the winter.
Divide and move perennials now. Dig up and store tender bulbs like dahlias, caladiums, cannas and tuberous begonias.
Plant hardy mums now so they will become well established prior to cool weather. Pansies, ornamental cabbage and kale can also be planted this month.
Irises with leaves that are flopping over may be infested with iris borer. The borer is the larva of a clear wing moth. The eggs are laid on the foliage in the spring and the larvae move down to the crown and bore into the rhizome. Dig up infested plants and cut out the larvae and damaged tissue. Re-plant the healthy rhizomes.
If you have fruit plantings in the landscape it is very important that you practice good sanitation now. Remove and dispose of all rotted or fallen fruits from trees, vines and bushes. This will help reduce the amount of disease inoculum and number of insect pests that over-winter and attack your plants next spring. Do not compost this debris, but dispose of it in the garbage.
September is a good time to prune out the dead raspberry and blackberry canes that fruited this past summer. Fall fruiting raspberries like ‘Josephine,’ ‘Caroline’ and ‘Heritage’ can be mowed to the ground in late winter.
If you happen to have a fig planting, harvest them when they soften slightly. Fall pears are beginning to ripen. Most pear cultivars are picked when background color begins to lighten, but fruits are still firm. Pear should be kept in the refrigerator and brought to room temperature to ripen. Asian pears should be allowed to ripen on the tree.
Pick an apple every few days when harvest time approaches to determine the peak harvest time. Harvesting fruit before peak ripeness will help you to minimize problems with yellow jackets and sap beetles. Again, remove and dispose of all rotted or fallen fruit from trees for disease control.
Finally, don’t forget the spring flowering bulbs. We are all familiar with tulips, daffodils, hyacinths and crocus ~ the standard bulbs for spring flowering displays. To add variety to you bulb plantings, consider using come of the mpre unusual or less well-known spring bulbs in your landscape.
Siberian squill (Scilla sibirica) produces bright blue flowers on 4- to 6-inch plants in early spring. They are easy to grow and prefer partial shade and multiply rapidly. Siberian squill are most effective when planted in masses under trees and shrubs, but are also suited to rock gardens and the edge of woodlands.
Another type of squill ~ Lebanon squill (a.k.a. striped squill) ~ is a hardy bulb that yields flowers with dark stripes of blue on white or blue petals. Blooming very early in spring and reaching 6 inches in height, the flowers are of an unusual color and have a spicy aroma. The plant likes sun or partial shade. This selection multiplies well and performs positively in rock gardens or pots, but does best in mass plantings.
Spanish Bluebell (Endymion hispanicus or Scilla hispanica) produces 12 to 15 nodding, bell-shaped flowers on 12- to 18-inch stems. Varieties are available in blue, pink and white and they do well in heavy shade.
The Guinea-hen Flower, Fritillaria meleagris, is a hardy plant that produces white or purple bell-shaped flowers with a distinct spotted or checkered pattern. The plant does well in light shade, with cool and moist conditions, reaching a height of 8 inches to a foot tall. The Crown Imperial fritillaria has bright red, orange or yellow flowers in groups of 10 on 3-foot tall stalks. The bulb has a distinct skunky scent, but don’t let that dissuade you. The flower is beautiful in the landscape.
One planting recommendation for all these bulbs is to plant them in a bed with sand between each bulb and then tilt the bulbs on their side to prevent water damage.
Alliums ~ ornamental onions ~ have become very popular in the garden over the last few years. They are grown for their colorful white, yellow or pink to purple flower clusters. They bloom from late spring to early summer and do best in full sun.
The Giant Allium (Allium giganteum) produces pinkish-purple flowers in a dense, globe-shaped cluster, 4 to 6 inches across. The solitary heads are borne atop a 3- to 4-foot-tall stem. The giant onion usually blooms in late June.
Lily Leek (Allium moly) has yellow flowers in a loose umbel and blooms in late spring. Lily Leeks grow 8- to 12-inches-tall and are best utilized in borders and rock gardens. Alliums are also deer resistant and provide dramatic color in late May, June and even July where it is a nice combination with the early-blooming perennials.
Happy gardening!

Marc Teffeau retired as the Director of Research and Regulatory Affairs at the American Nursery and Landscape Association in Washington, D.C. and he now lives in Georgia with his wife, Linda.