With the arrival of September, we begin the transition from summer to early fall with a jolt of cool nights and shorter, sunny days. Now is the time to revive the lawn, tuck spring-flowering bulbs into the sun-warmed soil, and line the front walk with a riot of chrysanthemums.
Shrubs and Trees:
- Mid-September through mid-October is a great time to plant or transplant trees and shrubs. Plants moved or planted new now will have up to two months to settle in and spread their roots before they go dormant. Prepare a hole twice the diameter of the root ball but at the same depth and water thoroughly. Mulching will help protect against large fluctuations in soil temperature and moisture. Be sure to stake or guy-wire tall plants to protect them from strong winds.
- Don't be alarmed if your evergreens, particularly pines and arborvitae, begin dropping older needles. Even though we refer to them as evergreens, the needles do not stay on the plant forever. It's normal for inner, older needles to turn yellow or brown and then drop off, leaving newer, green growth on the outside ends of branches.
- As the weather cools, begin watering established trees and shrubs less often, giving them time to harden off for winter, but continue to water 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 desiccated needles.
- September is definitely a key month to take steps for an even healthier lawn next year. Practices such as seeding, sodding, aerifying, dethatching, and fertilizing can all be done in early to mid-September.
- If you are making four fertilizer applications per season, your next application should occur sometime between September 1 and September 15 (the "Labor Day" application). Even for lawns fertilized only once a year, this would be the time. As with all fertilizer applications, time the application so that it immediately precedes a light rainfall or watering.
- Maximum chemical weed control begins in late September. Broadleaf weeds such as dandelion and creeping Charlie are more effectively controlled now, when more herbicide is absorbed directly into the taproot, than in the spring. Be sure to follow label directions on all herbicides, and choose a windless day to prevent spray drift.
- White grub damage is usually a late summer concern. So if irregular areas of your lawn start browning, carefully check the root zone by peeling back the grass on the edges of affected areas. Grubs will be present if they are in fact causing the grass to turn brown. If grubs are present, apply either trichlorfon (Dylox) or bendiocarb (Intercept) and thoroughly water into the soil.
Perennials, Annuals, and Bulbs:
- The return of cooler 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. You can buy a new container at Reds or bring in one of your own and we'll fill it with your choice of fall plants.
- Stop fertilizing roses and perennial flowers in mid-September to encourage dormancy.
- Move houseplants indoors before nighttime temperatures are consistently in the 50s.
- Spring flowering bulbs are in stock at Reds! Now is the time to buy iris, tulips, crocus, daffodils and many others for the best selection and glorious color next spring. For good root formation, bulbs need to be planted four to six weeks before the ground freezes, but planting too early can cause bulbs to sprout top growth before winter. Keep the bulbs cool (50–60°F) and away from ripening fruits that may produce ethylene until they can be planted in late September or early October.
- Poinsettias saved from last year can be reflowered for this year's holiday by placing them in total uninterrupted darkness for 15 hours a day, starting the last week of September and continuing through Thanksgiving. Do NOT leave the plants in darkness all day!
Fruits and Vegetables:
- Harvest crops such as tomatoes, peppers, eggplants, melons and sweet potatoes before the first frost, or cover the plants with blankets, newspaper, etc., (but not plastic) to protect them from light frost.
- Apples that will be stored should be picked before fully ripened.
- Potatoes that will be stored should not be dug until after the vines die. If they are reluctant to die, cut them off close to the ground and wait a week before digging.
- After harvest, avoid storing apples or onions with potatoes or carrots. The ethylene gas given off by the apples and onions will cause potatoes to sprout, and the carrots will taste awful.
- Transplant rhubarb, strawberries, and raspberries well before the first light frost so that some root development may take place. Rhubarb and strawberries deplete the soil of nutrients in a short time, so find new locations for them every three or four years.
- Rototill or dig compost, rotted sawdust, manure and other organic matter into the soil. Fairly warm temperatures this month will give these additions a chance to begin breaking down before the ground freezes.
- The home veggie garden can be improved by sowing a cover crop such as winter rye within the next month. It will be four or five inches high before winter comes and can be plowed or spaded in early next spring to add organic matter to the soil.
Slug time again! Clean up debris, old pots and places they can hide. With a lack of rain, the heavy dews bring them out to feast. Controlling slugs now, during their
breeding season, should result in fewer next year.
Many fall gardening tasks are weather-related. Here are definitions of some commonly used terms:
A light frost is from 28–32°F.
A moderate frost is from 24–28°F.
A severe frost is below 24°F.
In zone 5 the first frost usually comes sometime between October 20 and October 28.
Garden Links for September
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