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September is a good time to begin a compost heap. Begin to layer grass clippings, dried fallen leaves, soil, a handful of fertilizer, and a little moisture. Shredded garden debris can be added as annuals and perennials die back next month.
Pick a dry day this month to test your soil. Plant Information at (847) 835-0972 has listings of soil testing agencies. Follow agency instructions on where and how to collect soil samples. Refrain from adding amendments, fertilizers, or other chemicals to your soil until you know what your soil lacks.
Wait until trees and shrubs drop their leaves or undergo color change before planting them or digging and moving them to new sites. At that time they are entering dormancy and will not suffer as much transplant shock when moved.
Broadleaved and needled evergreens, both dwarf and standard, are best planted or moved by October 1. Water deeply and thoroughly at planting time and each week up until the ground freezes.
Continue to water large trees and shrubs, especially evergreens, until the ground freezes hard. Evergreens continue to lose moisture through their needles throughout winter and must have adequate water in their root zones to avoid winter burn or dessicated needles.
Wait until next month to fertilize any tree or shrub that looks like it might benefit from extra nutrition — for example, has stunted growth, has failed to fully flower or leaf out, or has undersized fruit or off-color foliage.
Winter protection of roses is not necessary until late November, when the ground has frozen.
Continue to deadhead both annuals and perennials to encourage additional flowers.
Return of cool weather is a good time to refresh annual containers with cool-season favorites such as pansies, ornamental cabbage and kale, chrysanthemums, or fall-blooming asters. Asters and mums purchased in bloom this month are usually greenhouse-grown and not necessarily hardy. To increase their chances of making it through the winter, plant them directly in garden beds, rather than containers, early this month so they can establish their roots for a good four to six weeks before frost. Water well and mulch plants right away.
Do not cut back perennials until their leaves and stems have lost all green color.
Daylilies and peonies can be divided or planted early this month. Water well to encourage healthy root development. Peonies should be planted so that the buds or eyes are no deeper than 2 inches below soil level. If planted too deeply, they will fail to flower.
Make final selections of spring-blooming bulbs but don’t plant any until later in October and November.
Early this month, entire lawns or bare patches may be seeded with appropriate grass seed mix.
Grubs chew grass roots, and they may be present if your turf begins to brown and lifts easily off the ground. Minor damage is usually not cause for treatment. Pull back turf and check for white, C-shaped larvae with black heads. If more than 10 to 12 grubs are present in a square foot of soil, treatment is advised. Chemical controls vary in their timing. Homeowners can spot-treat small areas immediately with a recommended control or, wait until the third week of next June to apply imidacloprid. As temperatures become cooler in fall, the grubs will move further down in the soil, making them out of reach of chemicals.
Consider core-aeration of lawn, if not done this year. Professional lawn services can provide the equipment (and the service itself) to remove plugs of soil and grass at regular intervals over entire lawn. Plugs are left on lawns to decompose. Core-aeration is recommended to help rectify compacted soil, heavy thatch accumulation, and poor drainage. Avoid this procedure when soil is quite wet.
Midmonth is a good time to apply fertilizer to lawns. Choose an organic product or a synthetic fertilizer with a 3-1-2 or 4-1-2 ratio. Moderate temperatures this month along with cool nights and adequate rainfall will spur grass growth, making September a good time to feed turf.
The next six weeks will provide an abundance of produce. Continue to harvest vegetables as they ripen. Warm-season crops like peppers and tomatoes must be picked as soon as possible. If an early frost threatens, cover these plants with baskets or light blankets. Refrigerating tomatoes causes them to lose their flavor. Store in a cool, 60- to 70-degree room for a few days.
Begin to harvest late-season squash and early pumpkins. Full-sized pumpkins need to remain on the vine as long as possible to achieve their maximum size.
Allow collards, kale, and Brussels sprouts to be hit with frost before harvesting. This improves their flavor.
Begin to harvest a second crop of any cool-season lettuces, spinach, peas, radishes, or chard that were planted in August.
Continue to snip herbs to use fresh, to dry, or to freeze. If herbs have gone to flower or seed, discontinue harvesting, since the flavor has then left the foliage.
Everbearing raspberry bushes will produce their fall crop on the top half of the canes. After harvest, prune out the top half of the plants. The lower half of the canes will produce fruit early next summer. After harvesting the summer crop, prune the canes to the ground.
Maintain good sanitation throughout the vegetable garden. Remove diseased plants immediately as well as those that have finished their growth cycle for the year. Compost only healthy plant material.
Cuttings from favorite or unusual varieties of annuals such as geraniums, coleus, begonias, and impatiens can be taken this month, potted up, and brought inside to a south-facing window. Some tender unusual container plants can be brought inside as whole plants — hebe, black mondo grass, mandevilla vine, and certain small geranium plants are a few. Many gardeners prefer to repot the plants and change the soil to a fresh, lightweight, soilless mix at this time.
Houseplants that have spent summers outside should be monitored in the event of a premature frost. Check plants carefully for any sign of insect or disease before bringing them indoors. Gradually reintroduce these plants to indoor conditions. Consider repotting and changing soil at this time. Do not change size of pot until spring.
Amaryllis bulbs that have summered outdoors must begin their dormant period. Remove bulb from container and shake off all dirt. Cut back all foliage, whether it is yellow or green, and set bulb on its side in a cool, dark room for several months until new growth appears.
To create a winter herb garden, dig up selected herbs such as thyme, basil, rosemary, or oregano. Repot in smaller pots, change soil to soilless mix, and cut plants back. Gradually introduce plants to indoor conditions before bringing inside to a sunny windowsill. Herbs will put out new growth, but it won’t be as vigorous or as tasty as the summer crop.
Plants brought indoors this fall might exhibit temporary “transplant shock” in their new environment due to changes in light and temperature. Sun-loving houseplants might suffer during cloudy winter season. If possible, consider supplemental artificial lights. Avoid overwatering houseplants. Cut back on fertilizer in general, except for plants intended to bloom all winter, such as miniature roses or geraniums.
Most houseplants appreciate a 10- to 15-degree difference in day and night temperature. Monitor plants for early signs of problems. When indoor heat is turned on, natural humidity disappears. Try to wash plants occasionally in a warm shower. Humidifiers and pebble trays can help raise humidity.
Pot up pretreated bulbs, such as amaryllis, paperwhite narcissus, and others, for holiday blooms.
Extra hardy bulbs not planted outside this month can be potted up and forced for indoor blooming. Plant bulbs in wide, shallow pots in a soilless mix. Large bulbs are planted side by side with just their tips showing. Little bulbs are planted with ½ inch of mix covering them. Water well and place pots in a refrigerator, cold frame, garage, or shed where the temperature remains between 35 and 40 degrees Fahrenheit. If storing in a refrigerator, cover pots with plastic wrap and avoid storing ripening fruit in same area. Some fruit releases ethylene gas, which inhibits flower formation. Major bulbs require 12 to 14 weeks of cold storage; little bulbs require a few weeks less. When pale yellow sprouts begin to show, pots can be brought out of cold storage into a bright but quite cool room (55 to 65 degrees F.) for about two weeks. As flower buds begin to develop, bring pots into a warmer room but avoid direct sunlight. Water as needed.
Watch weather conditions for an appropriate window of time to spray fruit trees or large deciduous trees with dormant oil. Spray if aphids, scale, or mites were a problem in the past. Temperatures must be at least 40 degrees Fahrenheit with no chance of freezing or rain within the following 24 hours. Avoid spraying on a windy day. Certain trees have a phototoxicity to dormant oil and should not be sprayed. A few common ones are arborvitae, beech, red maple, Japanese maple, sugar maple smokebush, blue spruce, blue cultivars of juniper, and yew. Call Plant Information if in doubt.
To reduce the spread of oak wilt, all oak pruning should be completed in March, or before the oaks begin active growth. Pruning should not resume until after the first frost, or around November 1.
Prune fruit trees in early March on a dry day before buds swell. As with all pruning chores, sterilize pruning tools with a 10 percent solution of bleach before each cut. Prune out sucker growth, water sprouts, and any diseased or dead branches. Remove crossing branches, rubbing branches, or those that grow toward the center or the plant rather than outward, away from the interior. Fruit trees benefit from having their canopies opened up to permit more sunlight and air into their centers.
Prune spring-flowering trees and shrubs immediately after they flower to preserve this season’s flower display.
Prune roses when the forsythia begins to bloom. When pruning roses, make a 45-degree cut above a healthy bud, angled away from the center of the plant. If not done last fall, prune hybrid tea roses and grandiflora roses back to 12 inches to reinvigorate growth. Prune out dried, darkened, and broken canes and any dead tips. Prune shrub roses to remove dead wood and very lightly to shape to size.
Fertilize woody plants four to six weeks before they begin new growth only if they have shown signs that they could use it. These would include poor leaf color, failure to completely fruit or flower, or stunted growth. Use a slow-release granular fertilizer or an organic product and water in well. Do not fertilize newly planted trees or shrubs. Wait one year before making this application.
Plant trees and shrubs before they break bud and when soil conditions permit. If spring weather is unusually wet, consider planting in the fall when the plants begin their dormancy. With all woody plants, avoid planting too deep. Research indicates that more trees suffer from being planted too deep in the hole than any other problem. Plant with one-third of the root ball above ground. Taper soil away from the trunk back to ground level. Mulch the entire root zone with several inches of shredded or chipped bark.