Don't clean up everything in your garden in fall. Leave ornamental grasses for beauty and the seed heads of perennials such as coneflowers to feed the birds. Avoid cutting back marginally hardy perennials, such as garden mums, to increase their chances of surviving a harsh winter.
Vegetable gardening tip: The optimal temperature for ripening tomatoes is between 68-77 degrees F. And at 85 degrees F, it's too hot for the plants to produce lycopene and carotene, the pigments responsible for the fruit color. Once temperatures consistently drop below 50 degrees F, green fruits will not ripen. Tomatoes that have a bit of color change can be brought inside to finish ripening.
Plant spring-blooming bulbs, such as tulips, daffodils, crocuses, and hyacinths, in the fall before the ground freezes. In general, place the bulb in a hole that's two to three times the depth of the bulb.
Deadhead spent flowers on spring-blooming bulbs so the plants send energy to the bulbs instead of into making seeds. Leave the foliage until it turns brown and can be removed with a gentle tug. The leaves store nutrients needed for the bulb to bloom the following year. Braiding or tying the leaves is not recommended because it reduces the amount of light to the leaf surfaces.
Fertilizer is not the answer to growing the best plants; soil quality is. Add organic amendments such as compost and well-aged manure to your soil. The best soil structure is crumbly, easy to dig, accepts water easily, and offers oxygen for plant roots. If you choose to use fertilizer, use an organic one to add nitrogen, phosphate, and potash.
Late summer or early autumn is the best time to divide and transplant spring-blooming perennials. The most commonly divided perennials are irises, peonies, hostas, and daylilies.
If your rhubarb sends up flower stalks, remove them so the plant will focus on foliage production, not seed production.
When transplanting container-grown plants, dig a hole larger than the soil ball of the plant to aid with root establishment.
Mound your potato plants deep under the soil and store harvested potatoes in complete darkness. Exposure to light turns the skin of potatoes green, an indication that the potato has produced a colorless alkaloid called solanine, a bitter-tasting toxin that, consumed in large quantities, can cause illness. Cut away any green portions or sprouts on potatoes to avoid the problem.
Most in-ground garden plants grow best with 1 to 2 inches of water per week. If not enough rain falls, water deeply once a week instead of watering lightly daily. Frequent, shallow watering only moistens the top layer of soil and encourages the plant's roots to move there instead of growing deeper.
Don't send your fall leaves away! Chop them up and use them as compost ingredients. Pulverized leaves can be left to nourish the lawn. After several hard freezes, when plants have gone completely dormant, you also can use 3-6 inches of shredded leaves as mulch over tender perennials to keep them dormant over winter. Remove the mulch in spring.
Avoid digging or planting in wet soil; working it damages the soil structure. Wait until the soil is crumbly and no longer forms a ball in your hand (it doesn't have to be bone-dry) to till or dig.
Understand your soil's drainage. Roots need oxygen, and if your soil is consistently wet, there are no air pockets for the roots to thrive. Many plants prefer well-drained soil, so amend your soil with organic materials to improve the soil quality.