We’ve had a warm, moist summer – maybe even more than a bit too moist for the liking of so many plants and trees in our gardens and landscapes. The long hot dry spell we usually expect during mid-summer just didn’t happen this year, and it at least where I live, there have been numerous threats of rain lately, but no significant rainfall. Everything’s starting to dry out, and some of my deciduous trees and shrubs are starting to shed their leaves. There’s a lot of damage control to heap onto the usual September gardening chores. So let’s jump in and sort out what needs our attention this time of year.
It’s likely that many plants and trees are suffering from some form of fungus infection. Now that the weather is dryer, you may start seeing an increase in powdery mildew, which thrives in warm dry, but humid, weather. Treating the plants themselves with fungicides, which are more geared toward prevention, may help the weakened plant survive as long as the damage isn’t too severe. Cleaning up debris from around your trees and plants will remove infected plant material and reduce the chances of reinfection. Fall is a good time to remove old mulch, which will also help reduce the presence of fungi and bacteria around your plantings. You can also assess whether your plantings are properly situated to minimize the development of fungal and bacterial issues. If they are susceptible to powdery mildew, are they planted too close together, or in areas that are too shady? If they rotted because of all the rain we had this summer, can the drainage be improved? Sometimes it’s a matter of relocating the plants, or shrubs that are suffering, and sometimes it’s best to just replace them with plants that aren’t susceptible to fungus. There are numerous suggestions for prevention and control of fungal infections, some of which are listed in the links below. We have a variety of solutions here at the nursery, and we’re happy to help you choose what works best for your situation.
In the vegetable garden, you can still plant beets, broccoli, cabbage, carrots, collards, lettuce, mustard, onions, radishes, spinach, and turnips in either seed or seedling form. If you already have greens and cabbages planted, you could still do a second planting of those same crops now. Continue to harvest ripening tomatoes and peppers. Don’t forget about your herbs, which can be dried or frozen for use during the fall and winter.

This is a great time of year to divide irises, peonies, daylilies, and many other perennials. Be sure to know the plant specific techniques required for successful division and propagation before digging.
This is a great time to divide and transplant perennials (irises and daylilies come to mind), or plant new perennials, trees, and shrubs. Most will have time to settle in their roots before the ground freezes, and some judiciously applied mulch will provide additional protection against the cold. Deadheading existing plants and shrubs is still on your to-do list as well, so don’t get too big for your breeches.

Planting sufficiently early in the fall is necessary to allow roots to dig into the soil, and allow the plant to harden before the first freeze.
If you already have an established compost pile, distribute some of that black gold around the garden to enrich the soil. It doesn’t take much to make a difference. Keep adding new material, such as fallen leaves and undiseased garden discards, to your compost pile.

Just a gratuitous picture of dairy cows in Ireland. Just kidding. If you use manure in your garden, make sure to fully compost it before adding it to your garden.
The weeds are probably just as much as an issue as they were in the spring, and the bugs, while not as bad, are still munching away in your garden. Weeds are more easily removed after good rain, so let’s hope for a good downpour or two soon. Sometimes, the weeds are the only thing holding down the dirt, so if you have areas where you haven’t quite decided what to do, it may make more sense to weed whack instead of ripping out the weeds by their roots. Speaking of erosion (and weed control BTW), you still have time to plant a quick growing cover crop such as buckwheat. Crimson clover and annual rye grass are also some good choices. You can handpick the bugs or use diatomaceous earth and insecticidal soap spray to deal with the little varmints.
Refreshing or replacing mulch will keep the weeds under control. With mulch, there are such things as too close and too much. Don’t pile up the mulch around the trunks of trees, or the stems of plants in your garden, and don’t apply more than several inches. For plants that are susceptible to disease or pests, the best advice is to throw away all the old mulch and put down a new fresh layer of mulch to discourage overwintering of either.
Now is not the time to neglect watering. Keep an eye on all your plants in the garden, paying special attention to the little guys you’ve recently planted, whether they’re winter veggies or baby perennials. Drastically reduce feeding to allow the plants to prepare for winter, and keep your mitts off the pruners. In fact, don’t even touch the shrubs and trees. We’re watching.

Camellias are another shrub that should not be pruned now or before it blooms again, unless you don’t mind losing blossoms.

Azaleas shouldn’t be pruned this fall, because the flower buds have already set. The exception would be to remove diseased or dead branches.

Some hydrangeas have already set their flower buds for next year, so pruning them now will remove the flower buds. Visit our blog on caring for hydrangeas for more specific information regarding proper pruning times and practices.
Sources:
http://www.walterreeves.com/seasonal-gardening-calendar/september/
http://extension.uga.edu/publications/detail.html?number=C943#September
Here are some links offering advice on recognizing and managing fungus infections on plants and in the soil:
https://growingagreenerworld.com/bacteria-fungus-and-viruses-an-overview/
https://www.almanac.com/pest/powdery-mildew
https://www.doityourself.com/stry/how-to-make-a-natural-fungus-fighter-soil-drench
https://homeguides.sfgate.com/treat-soil-infected-fungi-43722.html
https://wimastergardener.org/article/powdery-mildew/