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Weekly Gardening Tips for Your Area


To Do List: Zone 8

Susan Wells
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September 2012 To Do List, Zone 8

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

September is a month for looking back over the triumphs and mistakes of the summer garden season. If you’ve managed to keep your tomatoes disease free, or at least have pruned off the diseased branches and kept moisture consistent, for example, you probably are still harvesting. If not, your poor tomato plants are yellowed and withered and your sandwiches are much less tasty for lack of fat red slices.

Nonetheless, the joy of gardening is that there is always another season and no mistake is forever. As you are doing your summer cleanup and preparation for fall crops, make a few notes about which cultivars did well and which didn’t, so when you look for seeds to purchase, you may make the best choices for next year. Remember in the southern parts of Zone 8 to look for cultivars that are bred to manage in extreme heat. Now, on to fall!


  • Our southern Zone 8 growing season is so long that you are probably now harvesting second crops of beans and corn, perhaps even squash. Remember to keep everything cleanly picked to keep everything producing until frost around Nov. 15.  If you get them in the first week of the month, you may be able to get another crop of Straight 8 cucumbers, which only take 58 days to mature fruit.  Keep tomatoes producing with a little balanced fertilizer or compost side-dressing.
  • In the northwest, remember that mid-October will bring those cold rains, so be ready with cool-weather crops in place.
  • Image via Shutterstock

    There’s still time to harvest cool weather crops. Many leafy greens taste even sweeter when touched by frost.

    Prepare for your fall garden by spreading compost over your beds, digging it in and planting collards, cabbage, kale, turnips, mustards and chard. You can sow seeds directly in the ground or set out transplants. Once the seeds are up, cover with row cover to keep the late season bugs at bay. The row cover will do double duty as cold weather approaches, extending the season until temperatures drop below about 20 degrees.

  • Dig another bed for fall root crops such as garlic, onions, carrots and potatoes. Dig deeply and amend with coarse sand (except, of course, in areas where your soil is already dominated by sand) and plenty of organic matter. Sow carrot seeds thinly in rows about six to eight inches apart. Thin seedlings to four to six inches apart. If you have clay soil, try Nantes or Miniature cultivars, which adapt to heavy soil. Tuck onion sets in everywhere they will fit. Don’t plant too deeply as the bulbs like to break through the soil surface. Try hardneck, softneck and elephant garlic to see which ones you like best. Bury the cloves three times their length deep with the pointed end up. Harvest when the leaves begin to yellow.
  • For potatoes, till deeply, digging in manure or compost, and set seed potatoes about 18 inches apart in trenches six inches deep. Cover seed potatoes with about two inches of soil. As the leaves grow above the soil, fill in with more dirt until you have plants growing in hills about six inches tall. Mulch heavily and keep moist until the foliage begins to yellow. Dig potatoes and enjoy! Norland Reds and Yukon Golds are good cultivars for our hot climate.
  • 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 pin-prick 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 any treatment is applied.


Image by Rhian vK via Flickr

Use a sharp, clean knife to divide iris rhizomes in the fall. Overcrowded mats will suffer if you don’t divide them.

  • Plan your new flowerbeds and refresh old ones with compost and new mulch.
  • Order or buy your seeds and bulbs for fall planting of perennials.
  • Divide daylilies, iris and peonies now. Cut the leaves of lilies and iris back to about 12 inches and replant healthy rhizomes. Let iris rhizomes see a little sunshine by planting shallowly. They benefit from digging in a little bone meal in their beds.
  • You may continue to fertilize roses this month, but stop next. Prune climbing roses after they bloom.
  • Your Camellia sasanquas should be just coming into bloom so step back and enjoy. However, September is a great month to make sure your C. japonicas also have a beautiful bloom time. Dig in that last dose of fertilizer now. Also look at the flower buds on your bushes. Wherever you find two buds together, pinch one off. That will make for larger, longer lasting blooms from the bud left to flower.


  • The seeds of hardy annuals may be planted now and fall bedding plants such as chrysanthemums may be planted now.
  • Remove spent flower heads and seed pods.
  • Cut back leggy stems of impatiens, petunias and other flowering annuals. You may get another flush of blooms before frost.
  • Plant a last bunch of zinnias for one more fall bloom.

Image by KitAy on Flickr

Trees add beauty and value to your landscape. Plant them in fall’s cooler weather to lessen the stress on them as they develop strong roots.


Trees and Shrubs

  • Sadly, not all trees and shrubs are heat tolerant. This year’s extreme heat wave has damaged some of our largest and most important trees. Even irrigation cannot shield plants from heat damage.
  • Extended periods with temperatures above 95 degrees Fahrenheit slow the biological function of nearly all plants. This is a natural response and slows down the rate of “transpiration,” or the exhaling of water vapor from the leaves. However, slowing down biological function for too long gives the plant less time to make and store its food through photosynthesis and can damage the plant permanently.
  • Some plants are biologically more adapted to handle heat than others. For example, a silver maple may be killed or severely damaged by prolonged heat waves, while a post oak will thrive.
  • Given that trees and shrubs are the largest, most expensive and most important elements in our landscape, making sure you are choosing the right plant for the right purpose is critical. If some of the large plants in your landscape are damaged beyond repair, begin now to rebuild with species that can handle what seems to be an increasingly hot climate in the southern and western zones.
  • Now is the time to assess as much as possible whether the recent extreme temperatures have damaged your trees or shrubs and determine what to do about it. October is the best month to plant trees to give their roots a chance to become established before cold weather sets in. So in September, assess whether you need to replace or renew the larger members of your landscape team, remove any damaged beyond repair, decide the best places to plant new ones and either purchase or order the best cultivars for your area. When October comes, you’ll be ready to plant.
  • Some shade trees that can handle heat: Southern sugar or Florida maple; red, scarlet or swamp maple; southern magnolia; laurel, swamp or sweet bay magnolia; southern or rusty blackhaw; post and scarlet oak; river or red birch.  Conifers (some are evergreens) that work in heat are Arizona cypress; bald cypress, pond cypress, arborvitae, and loblolly pine. Ornamentals include crape myrtle, star magnolia, ginkgo, rose of Sharon or shrub althea, and bay laurel.
  • Look for these and other heat-handling cultivars in your Home Depot garden center.
  • And remember, here at the end of summer, if dry, hot weather continues in your area, water your trees and shrubs first. The rest of the garden is much easier to repair or replace.


Image by thisreidwrites, Ruthanne Reid, via Flickr

Consider overseeding or patching your lawn this fall. Many Home Depot stores rent lawn and garden equipment. Fertilize again in fall with a slow release fertilizer, to promote root growth.

  • This is a good time to re-assess your lawn. If you have bare or thin spots in, you may overseed later in the fall. If the lawn is healthy, just follow a regular schedule of  watering and fertilizing to prepare it for winter and next spring.If you are starting a lawn, either Bermuda or St Augustine is a good choice because both thrive in the hot summers.
  • If you plan to over-seed your Bermuda, stop fertilizing. Following a light dethatching, this month, you’ll be ready for over-seeding at the end of the month and into October with an annual rye grass.  This will keep a fresh green look to your turf  over the winter, but will die back with the hot weather, adding extra nitrogen to the soil.
  • If you are not planting a winter lawn, add about 10 pounds of Ironite for every 1,000 square feet of turf, with a broadcast spreader (100 ft  x100 ft). This spreader is available in the outdoor garden section at your neighborhood Home Depot.
  • Most turf will benefit from core aeration and dethatching. It improves water penetration, turf root growth, increase effectiveness of fertilizers, and relieves compaction. The plugs of soil, which are the cores, can remain on the turf.
  • You still need to fertilize your lawn when it’s cool to promote root, not top, growth. Use a slow release fertilizer with iron and a higher potassium rating (‘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 Home Depot, too.


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