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Weekly Gardening Tips for Your Area


To Do List: Zone 6

Susan Wells
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September 2012, Zone 6

Click the image to enlarge this map of the USDA Plant Hardiness Map and find the zone where you live.

September is a busy month in the garden. Weeding is not yet over, and our fall cleanup begins with cutting back everything that has finished blooming and perennial dividing. Now is a good time to take cuttings for next year’s garden. Prepare the vegetable garden for fall planting. Purchase floating row covers to use on tender plants as temperatures begin to dip at night. Have your camera ready to document spectacular fall color changes.


  • Start your fall lettuce seeds in a cool spot. Sow directly in the garden when temperatures are below 80 degrees, or start seeds in flats and transplant them to the garden after three to four weeks. Stagger your transplanting schedule a week apart and use row covers. You may be harvesting lettuce into November and December.
  • Trim remaining tomatoes and peppers to 18 inches (making sure to leave green fruit intact), side dress with compost and water deeply. Once night time temperatures start dipping into the low 70s, you probably aren’t going to get any new fruits forming, but you can speed up ripening of the existing green tomatoes. Pinch off any new flowers.
  • Options for ripening green tomatoes indoors: place them on a sunny window sill, blossom side down. Wrap individual green tomatoes in newspaper and layer in a box, no more than 2 layers deep, in a dark, dry spot. It usually takes 3-4 weeks for the green tomatoes to ripen, but check frequently and remove any fruits that show signs of rotting. Or place the green tomatoes in a paper bag with a ripe apple. The apple gives off ethylene gas, which speeds up ripening. Check the bag daily.
  • Pick remaining herbs on a dry morning after the dew has evaporated. Herbs’ oils are most concentrated in the morning. If you are drying your herbs, they should be kept at a cool and dry temperature, with good air circulation. Wash herbs only if they are dirty or have been treated with chemicals.
  • Image by E. Kopyshev via Flickr

    Pruning raspberry bushes does more than help control their size. Removing old canes also helps prevent diseases and pests from spreading. Make sure to discard or destroy them, instead of tossing them into the compost heap.

    Cut back the branches of blackberry and raspberry bushes to 4 feet tall and support with wire trellis or fence. Insects will over-winter in dead canes, so remove and destroy them. Do not add to your compost.

  •  Blueberry bushes can be planted at the end of the month. Mulch with pine needles and /or oak leaves to maintain acidic soil.
  •  Pick up your new grapevines from Home Depot’s Outdoor Garden section To plant, prepare a well drained, deeply tilled (30 inches deep) fertile, loamy soil. Well-rotted manure or compost should be added at the rate of 15 – 20 pounds per 100 square feet (10’ x 10’ plot). If your grape cultivar is not self-pollinating, plant an additional vine for more fruit. Always trellis your grape vines for support.
  •  Flare-ups of spider mites have been reported during dry weather on tomatoes and other vegetable crops. Because mites are tiny, they are often overlooked or misdiagnosed as a disease. Infested leaves have fine webbing on the leaf undersides. Tomato leaves damaged by spider mites usually have yellow blotches, while bean leaves show white stipples or pinprick markings from mite feeding. Pumpkins can tolerate moderate levels of mites, but watermelons are more sensitive to injury from mite feeding. Mites have many natural enemies that kill them, such as lacewings, ladybugs, and pirate bugs. These helpful predators are often killed by pesticides so be careful how you treat them.


  • The flower of the month for September is the aster. It’s been blooming since midsummer and will last up a frost. If you didn’t plant it in the garden this year, you may want to consider it for 2013.
  • Sorry… you’ll still need to keep weeding. Some weeds germinate in the fall and have to go.
  • Perennials need to be divided every few years for good healthy plants. Examine leaves for aphid damage and or fungus. If it exists, cut the leaves & dispose of them. (When finished with this task, clean tools with alcohol or a solution of chlorine bleach diluted with water.)
  •  This is a good month to divide your bearded iris.
  •  Though a truly lovely perennial, the purple loosestrife (lythrium salicaria), is highly invasive, when growing in the wild.  As it establishes, it competes

    Image via Liz West via Flickr

    Purple loosestrife is an aggressive perennial that can choke wetlands, degrading the habitat where wildlife and fish feed. It can also invade crop and pasture lands. Although the plants are attractive, they should be removed to prevent them from spreading.

    with and replaces native grasses and other flowering plants that provide a higher quality source of nutrition for wildlife. The highly invasive nature of purple loosestrife allows it to form dense stands, restricting native wetland plant species thus reducing habitat for waterfowl. If you have it growing wild, please remove it, and don’t plant it in your garden.  With the exception of the state of Florida, it is invasive everywhere in the contiguous US.

  • As somewhat cooler weather moves in, be ready for the hardy appetites of warm-blooded garden pests. Voles are active breeders, often producing up to five litters a year. In warmer climates, they can breed year round. At around three weeks of age, voles can begin breeding. As herbivores, voles focus on flowerbeds and vegetable gardens. Create a 1/4” hardware cloth basket to serve as a wrap-around, buried pot for your prized flowers and plants. This will allow the roots to reach through the basket and make it easier to lift from the ground if transplanting.


  • Summer’s high heat may usher in an early leaf drop in September. Begin collecting fallen leaves to add to the compost bin for next year’s garden.
  •  Warm soil temperatures and cooler nights make September through October an excellent time for planting trees and shrubs. Water new transplants deeply, then mulch out to the drip line. Do not bring mulch up to the trunk.
  •  When planting new trees and bushes, select the most appropriate site for the specimen. This early decision will minimize stress factors in the future plus allow for optimal performance and enjoyment. It’s tempting to plant several shrubs to fill in, for example, where 1-3 will fill the space just fine when they are mature.
  • Image by storebukkebruse via Flickr

    Prune your fruit trees in fall to remove diseased branches.

    Canker is a deadly disease caused by a fungus, affecting many kinds of stone fruit trees, such as peach, plum, nectarine, apple, pear and apricot trees. The infected parts of the wood turn dark as the fungus eats away at the fruit tree. To treat canker in fruit trees, you must first cut out the cankers. After pruning out branches on trees infected by a bacterial canker, clean the pruners in a solution of 1 part chlorine bleach to 4 parts water between each cut and cut several inches below the infection. A bacterial canker pathogen sends out spores in the fall. Don’t cut out a canker if it is more than half of the branch’s circumference. This will likely kill the branch, so you may be better off removing the branch altogether if you can. You can spray a 50 percent copper based fungicide mix late in the season, in an attempt to keep the spores from growing and infecting new areas. The soil can also be treated for nematodes, which can also transfer the fungus. Follow the directions on the label closely and repeat the application two more times during the fall.

  •  Yellowed leaves usually indicate an iron deficiency, whether on your roses, gardenias or trees. Spray the leaves with chelated iron with a drop of liquid soap added to the mix. The liquid soap acts as a ‘sticker’ for the chelated iron, helping it linger on to the plant material.
  •  Roses: Hose off the foliage 1-2 times a week to remove dust, spider mites and potential white flies in the morning. If there has been no rain, water  about every three days, applying about five gallons of water to each plant. Roses and hydrangeas are lightly pruned, primarily by removing the spent flower heads and removing dead or damaged wood. Climbing roses are pruned and retied to the structures on which they are supported.
  •  If you have a strong, young nut tree, prune it to eliminate branches within 8 feet of the ground, and maintain one central trunk.


  • Stop fertilizing Bermuda if you are going to over seed with rye next month. September is also a good month to lightly dethatch Bermuda grass.
  • Most turf will benefit from core aeration and dethatching. It improves water penetration, turf root growth, increases effectiveness of fertilizers, and relieves compaction.
  • You only need to fertilize your lawn, once in the fall. Use a slow release fertilizer with iron and a higher potassium rating (the “K” of the NPK ratio). Potassium will stimulate root growth and increase disease protection.
  • Water immediately after applying the fertilizer to promote quick absorption.
  • If your turf has been plagued by moles, consider rolling it with the heavy concrete or water filled rollers. This will crush their tunnels. The rollers often are available for rental at your neighborhood Home Depot.



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