It's hot, but cooler temps are in sight. Here's what you should be doing in the garden.

If you had asked me back in January what the weather would be like the first week of September, I would have said the days will be hot, humid and uncomfortable. And I would have been right.

If you ask me now what the weather will be like the last week of September, however, I’d have to say I’m not sure.

In September, the seasons are beginning to change. It likely will be hot, but there is always the chance that cool fronts may make their way through, lowering the humidity and dropping nighttime temperatures into the low 60s or even the 50s.?

For me, this time can be summed up as the “waiting to exhale” month. We can see cooler weather off on the horizon, but we know we are definitely not finished with summer.

A gardening transition

So, what to do now while we are waiting for cooler weather? It is not unusual to see beds of tired, played-out flowerbeds in landscapes this month. Our exceptionally long summer growing season, from May to October, may be more than many annuals can live up to.

With careful selection, however, flower gardens can hold up well through summer heat and still look attractive now. Note which flowers have held up best and which played out far sooner than you would have liked. Enter this information in your garden journal, and it will help you when you make your summer bedding-plant selections next year.

If you have beds where the warm-season bedding plants are finished and need to be removed, you have three options for what to do after the plants are taken out.

• You could simply clean out and mulch the area, and replant with cool-season bedding plants in October or early November.
• Plant more warm-season bedding plants to bloom until it’s time to put in the cool-season plants in November. (Given this is only a couple of months off, you won’t get a great return your investment.)
• Finally, you could replant the area with some of the more heat-tolerant cool-season bedding plants that often become available sometime in September, such as petunias, snapdragons, nicotiana or dianthus.

WHAT TO ENJOY: Start watching for the wonderful display of wildflowers we have each fall along interstates and especially country roads. I just saw some purple tall ironweed (Vernonia gigantea) starting to bloom. The display runs from now through late November. In addition to the tall ironweed, some of my other favorites are mist flower (Conoclinium coelestinum), narrow-leaf sunflower (Helianthus angustifolius), asters (Aster species) and goldenrod (Solidago).

CHORES AND MORE: If you haven’t pruned back your repeat-flowering roses (the vast majority of the roses we use in our landscapes), you need to do it now. Cut bushes back by about one-third, remove any dead wood and fertilize your roses. This prepares them for the outstanding fall blooming season.

Caladiums generally begin to finish in late September. When about two-thirds of the leaves of caladiums have fallen over and they are looking tired, it’s time to dig the tubers. Caladiums may return the next year if left in the ground, but it is far more reliable to dig them and store them indoors over the winter.

The hurricane season is kicking into high gear now, and if you haven’t already done so, it’s time to look over your landscape. In particular, larger shade trees should be carefully evaluated to make sure they are in good shape. Large dead branches must be pruned off and dead trees removed entirely.

Finish pruning shrubs and hedges in September. Late, heavy pruning will stimulate growth in the fall and increase the chance of cold damage to your shrubs. Remember, sasanquas, camellias, spring-flowering shrubs and gardenias and hydrangeas have already set their flower buds. Any pruning now will remove flower buds and reduce the floral display.

Do not apply fertilizers containing nitrogen to landscape plants that will be going dormant for the winter. Fertilizing trees, shrubs, lawns and ground covers with nitrogen in the fall can reduce the hardiness of some plants and promote winter injury.

In the vegetable garden, plant transplants of tomatoes and peppers and seeds of squash, cucumbers, bush snap beans and bush lima beans immediately. You may also plant seeds or transplants of cool-season vegetables like broccoli, cauliflower, Brussels sprouts, Chinese cabbage, cabbage, collards, mustard, kale, Swiss chard and kohlrabi, and seeds of turnips. Shallots and bunching onions may also be planted using small bulbs called sets.

Water established vegetables deeply and thoroughly twice a week during dry weather. Newly seeded beds, however, should be watered daily until the seeds come up. New transplants also need to be watered more frequently.

Chinch bug damage is showing up around the area. Tan, strawlike dead areas that show up in your lawn and get larger indicate chinch bugs, especially if the weather is hot and dry. Treat promptly with bifenthrin (Talstar) or other products labeled to control lawn insects.