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Weekly Gardening Tips for Your Area


To Do List: Zone 9

Susan Wells
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September 2012 To Do List, Zone 9

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. Unfortunately, weeding is not yet over. Our fall cleanup begins with cutting back everything that has finished blooming plus dividing perennials. Leave several seed heads in the flower garden for the birds. It continues to be a good time to take cuttings for next year’s garden. Before bringing your houseplant indoors, spray them with a soapy solution then rinse thoroughly to take care of insects that have been living with them outdoors. Continue to turn your compost. Add an additional compost pile for this month’s garden and leaf cleanup, to be used in the spring. Purchase floating row covers to use on tender plants at the end of the month as temperatures begin to dip at night.  Re-assess your lawn and come up with a plan.


  • Trim remaining tomatoes and peppers that are still bearing. Do not cut off ripening fruit. The plants can be cut back as dramatically (18 inches from the ground), and side dressed with compost. Water deeply. In the middle of the month, feed again.
  • As temperatures drop below 90 degrees later in the month, seeds of cool season crops can be sown directly into the garden. They are beets, celery, carrots, chard, endive, peas, green onions, parsnips, lettuce, bok choy, broccoli, brussel sprouts, cabbage, cauliflower, collard greens, kale, lettuce, leeks, mustard, radishes, turnips and spinach.
  • Image via Shutterstock

    Leafy greens are cool season crops. Many taste better after they’re touched by a light frost.

    Check temperature forecasts before transplanting ‘seedlings’ of tomatoes, lettuce, strawberries, onions, broccoli, Brussels sprouts, cabbage, cauliflower, celery, chard, lettuces this month. (Lettuces need to be below 80 degrees.) Remember to spray seedlings daily, to keep them from drying out.

  • If slugs have been eating your cabbage leaves, this season, spread a powered garden lime or agricultural-grade diatomaceous earth beneath your new plants this fall. It will burn and dehydrate the slugs’ soft bodies.
  • Continue to feed strawberries with a tablespoon of houseplant food to a gallon of water to stimulate good growth. If strawberries did not do well last season, transplant them in another bed to avoid disease.
  • Pick up your new grapevines from Home Depot’s Outdoor Garden section. The grape vines need to be well established over the fall and winter before the heat of summer rolls back in. For the grapes, prepare a well-drained, deeply tilled (30 inches deep) fertile, loamy soil for autumn planting. Pack the soil firmly around the root to eliminate air pockets, which may increase the chance of disease. A depth of 30 inches does seem extreme, but bear in mind that grapes have a very deep root system and we want to make it an easy transition.  A well rotted manure or compost should be added at the rate of 15 – 20 pounds per 100 square feet (10’ x 10’ plot). Be careful to not spread your manure / compost in your path areas. Use it only where you need it. If your grape cultivar is not self-pollinating, plant an additional vine for more fruit.  Plant most hybrid cultivars 8 – 10 feet apart, in the same row. Plant rows about 10 feet from each other.
  • Flare-ups of spider mites have been reported during dry weather, on tomatoes and other vegetable crops. Spider mites are tiny, and 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 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, such as lacewings, ladybugs and pirate bugs, but these helpful predators are often killed by pesticides. If white flies have been a problem in the vegetable garden, you may elect to put your seedlings out in October after they are gone, or place seedlings under a floating row cover.
  • Remove the covering from your soil solarization project by the end of the month (see last month’s entry). The weeds should be dead by then, and you can consider using this space for planting your fall garden.


  • Don’t stop weeding yet. September will shuttle in a new batch of emerging weeds. You can sprinkle the granules of PREEN weed preventer in your flower beds after weeding. Follow directions for use.
  • Remember to not add weed seeds, diseased or bug-infested debris to your compost. This helps avoid problems next spring.
  • Side-dress flower beds with a light compost and resist planting new perennials until next month.
  • Prepare beds for bulb planting next month. Some bulbs need to be chilled in the refrigerator for 4-6 weeks prior to planting to insure proper blooming.
  • Image by Rhian vK via Flickr.

    Divide crowded mats of iris rhizomes for healthier plants and better blooms next spring. Use a sharp, clean knife to avoid spreading disease.

    Bearded iris need to be divided every few years for good healthy plants. Examine leaves for aphid damage. If it exists, cut the leaves & dispose of them. (When finished with this task, clean tools with alcohol or a diluted chlorine bleach solution.) Make sure that when you are transplanting your iris rhizomes, that they are not planted too deeply. The rhizomes should be slightly exposed at the soil surface.

  • The summer’s lovely orange blooms from the butterfly weed will now begin to display their showy, silky seedpods. A native perennial, it can thrive in poor soils. Though they do not transplant easily, the butterfly weed is a prolific self-seeder. (You may want to pick the seed pods before they take over available real estate and share them with friends.)
  • ‘Autumn Joy’ sedum will begin to become rosy pink, aging to a rust colored red over the next few months. This perennial succulent offers year round seasonal interest in any garden and container.
  • Ornamental grasses make a lovely show in the fall. By the end of September, bloodgrass, broom sedge and plume grass turn shades of red to a coppery brown.
  • ‘Fountain’ grass will share bottlebrush seed heads this month. When planted in masses, they dance with the slightest of winds.
  • With light dead heading, you may be able to stretch the blooming of your coreopsis through the fall.
  • As somewhat cooler weather moves in, be ready for the hearty 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 gardens. Moles, on the other hand, eat insects and can be beneficial in the garden, other than their unsightly tunnels that can disrupt a manicured lawn.
  • If you are worried about vole damage, create a basket out of 1/4” hardware cloth to serve as a wrap around, buried pot for your prized flowers and plants. This will protect the plant while allowing the roots to grow through the basket.
  • Though a truly lovely perennial, the purple loosestrife (lythrium salicaria), is highly invasive, if it escapes to the wild. As it establishes, it competes and replaces native grasses and other flowering plants that provide a higher quality source of nutrition for wildlife. The clumping 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.
  •  If you have a stone pathway winding thru your sunny garden, consider planting creeping thyme to soften edges of the pathway. Plant it at least six inches from the stone, as it will creep. Within a few years, it will transform the path, both visually and aromatically.

Trees, Shrubs And Bushes

Image by KitAy via Flickr.

Trees add beauty and economic value to your landscape. Plant them in fall so they have time to develop a strong root system before warm weather returns.

  • Look up! If you see distressed tree canopies, call in an arborist to assess the situation. Long periods of drought followed by excessive rain can take a toll on trees. Remember it is always easier to repair a garden than to replace an established tree.If watering restrictions are in place in your locale, when you can, water your trees first. Continue to water on the summer schedule (once a week for shrubs and every two weeks for trees), if you’ve not had rain.
  • Roses: Hose off the foliage 1-2 times a week in the morning to remove dust, spider mites and potential white flies. If there has been no rain. water roses about every three days, applying about five gallons of water to each plant.Fertilize with a slow release, complete rose food in the middle of the month. Always water, deeply, prior to and after feeding. Prune out the dead canes and weak top growth, but resist heavy pruning. This month, sprinkle ¼ cup of Epsom Salts (magnesium sulfate) per bush, to encourage new growth.
  • Yellowed leaves often indicate signs of 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.
  • Always thoroughly clean your sprayer in between chemical changes.
  • If you didn’t fertilize your citrus during August do it now. Use ammonium sulfate. This last citrus fertilizing of 2012 will help make larger fruit. Do not apply fertilizer at the trunk of the citrus trees.  Apply it 2/3 out toward the drip line (the circle formed by the tips of the branches) to reach the feeder roots where it will be most effective.
  • Lemons can be picked as needed later in September even if the fruit is still green.
  • Take time to trim inside your citrus trees, removing the water sprouts and cleaning out any dead wood. (This will make fruit picking much easier.)
  • 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. (Though many stone fruits need a good frost, some will grow for us in Zone 9.  Check with your local county extension service for a list of trees for your area.) 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 9 parts water between each cut and cut several inches below the infection. A bacterial canker pathogen sends out spores in the fall.  You can spray a copper based fungicide mix late in the season, in an attempt to keep the spores from growing and infecting new areas.  Follow the directions on the label closely and repeat the application two more times during the fall. Use a fungicide that contains 50 percent actual copper. The soil can also be treated for nematodes, which can also transfer the fungus. 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.
  • Avocado trees are resilient, but will not tolerate growing in standing water. They need at least 6 to 8 hours of sunlight daily to maximize their ripening in the fall. Avocados do not ripen on the tree. (Do not eat fruit once it’s dropped to the ground.) Pick a few avocados and place them on your kitchen counter out of direct sun. Mature fruit softens within three days to two weeks.
  • At the end on the month, begin planting non-frost sensitive trees and shrubs from containers. Soil temperatures are still warm enough to help roots establish quickly. After planting, water deeply. Be careful to not over water newly planted trees but keep the soil moist for a few weeks to allow roots to begin to grow.


  • Image by thisreidwrites, Ruthanne Reid, via Flickr.

    Fall is prime-time for reseeding or overseeding your lawn.

    In September, 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 fertilizing to prepare it for winter and next spring. For Zone 9, Bermuda or St Augustine is a good choice because they 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 and 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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