Good watering will fortify plants for winter's slumber

Cooler September weather is a boost for many kinds of plants. Lawns resume growing, annuals in containers rejuvenate with cooler soil temperatures and non-native plants appreciate relief from scorching summer heat.

For optimum plant health, provide supplemental irrigation during weeks with less than 1 inch of rainfall until the ground freezes. Good watering practices in fall help to fortify plants for winter and provide a head start for next year.

Here's what you need to do in the garden this month:

Trees and shrubs

h Minimize transplant shock by waiting until trees and shrubs have dropped their leaves or undergone color changes to plant or move them. If a tree or shrub has lost leaves or changed color prematurely because of stress from drought, pests or disease, consider postponing moving the plant.

h Broadleaved and needled evergreens, both dwarf and standard, are best planted or moved by Oct. 1. Water deeply and thoroughly at planting time and each week up until the ground freezes.

h Continue to water large trees and shrubs, especially evergreens, until the ground freezes hard. Evergreens lose moisture through their needles throughout winter and must have adequate water in their root zones to avoid winter burn or desiccated needles.

h Wait until October to fertilize trees or shrubs that might benefit from extra nutrition, possibly because of stunted growth, failure to flower, undersized fruit or off-color foliage. Avoid fertilizing healthy trees and shrubs to help prevent unnecessary chemicals from leeching into groundwater and lakes.

Flowers

h Continue to deadhead annuals and perennials to encourage additional flowers.

h Do not cut back perennials until their leaves and stems have lost all green color.

h Peonies can be divided or planted early this month. Water well to encourage healthy root development. Peony buds or eyes should not be deeper than 2 inches below soil level. If planted too deeply, they will fail to flower.

h Refresh annual containers with cool-season favorites such as pansies, ornamental kale, chrysanthemums or fall-blooming asters. Asters and mums purchased in bloom are not necessarily hardy. To increase their chances of surviving winter, plant them directly in garden beds so they can establish roots for four to six weeks before frost. After frost, mulch immediately and continue to water well.

h Make final selections of spring-blooming bulbs but don't plant any until later in October or November.

Lawns

h Early this month, entire lawns or bare patches may be seeded with appropriate sun seed mix. Keep soil moist until seeds germinate. Water often until grass is established.

h Midmonth is a good time to fertilize lawns. Choose an organic or synthetic product with a 3-1-2 or 4-1-2 ratio. Water well following application.

h Consider core-aeration of lawn to help rectify compacted soil, heavy thatch accumulation and poor drainage. Professional lawn services can provide the equipment or service to remove plugs of soil that are left on lawns to decompose. Avoid procedure when soil is wet.

Edible plants

h Warm-season crops like peppers and tomatoes must be picked as soon as possible. If an early frost threatens, cover with baskets or light blankets.

h Begin to harvest late-season squash and early pumpkins. Full-size pumpkins need to remain on the vine as long as possible to achieve maximum size.

h Begin to harvest second crop of any cool-season lettuces, spinach, peas, radishes or chard that were planted in August.

h Continue to snip herbs to use fresh, to dry or to freeze. Discontinue harvesting once herbs have gone to flower or seed.

h To improve flavor, allow collards, kale and Brussels sprouts to be hit with frost before harvesting.

h Remove diseased plants immediately as well as those that have finished producing this year's crop. Compost only healthy plant material.

Houseplants

h Carefully check houseplants that spent the summer outside for any sign of insect or disease before bringing them indoors. Gradually introduce these plants to indoor conditions unless a premature frost threatens. Consider repotting with fresh soil but do not change size of pot until spring.