September is a great time to sit back and enjoy the garden
September marks the end of the summer season and the onset of fall, which officially begins Sept. 22.
As the weather grows cooler and milder, we’ll see the change in the plants, shrubs and trees. Foliage begins to change and the colors of the berries and fruits become more prominent as the leaves die back and fall. An early frost can occur in September and, if so, it will affect the fall foliage color and when it will peak in Ohio. For Ohio, the usual peak color period is from mid- to late-October.
Early frosts are often mild this month and do not damage most annuals, which will keep blooming until the first hard frost. September is a wonderful time to enjoy your gardens as the tasks of weeding and watering are less demanding now and the milder weather often brings out the best in many flowers and foliage plants.
With Sept. 22 not far away, the following reader questions bring up some fall interests.
Q: Will the mums I plant in the fall come back next year?
A: We are seeing mums for sale in the garden centers now because this is their peak time for blooming. They handle the cool fall weather well and produce some beautiful bright colors for our tired garden beds, planters and gardens. However, they come back in the spring more dependably if they are planted in the spring.
To give fall planted mums a better chance of coming back, it is a good idea to cut them back when they have finished blooming and give them a good mulching after the ground freezes. Planting mums in the fall in a protected area also will help them during the cold months.
Established mum plants should be divided in the spring by removing the plant, cutting out the dead center and replanting the strong outside shoots.
Q: My perennials are beginning to look dry and leggy. Which ones should I cut back now and which ones should I cut back in the spring?
A: Any diseased perennial should be cut back now and all of its foliage removed and destroyed so that the disease organisms will not winter over in the ground and re-infect plants next year.
Phlox, peonies, and bee balm should be cut back now for this reason. Asparagus and irises can also harbor harmful insects and should be cut back now.
On the other hand, some perennials add winter interest to the garden with their dried flowers, seed heads and foliage. Other perennials, such as coneflower seed heads, provide food for wildlife and birds. Dead foliage can also provide winter cover for wildlife so it is a good idea to leave all of these to cut back in the spring.
Q: I’ve heard of “hardening off” a plant in the spring but what does “hardening off” plants in the fall mean?
A: The process of “hardening off” a plant in the spring is quite different than the “hardening off” done in the fall. Beginning in April or early May, gardeners “harden off” plants by placing them outdoors in a sheltered area during the warmest part of the day to prepare them for later planting in gardens of beds. This practice helps young plants to adjust to growing outside after being raised indoors or in greenhouses.
“Hardening off” in the fall is a process that helps prepare established plants in beds, yards and gardens for the cold, harsh weather of winter. This process is accomplished by withholding water so that growing shoots can lignify (produce a tough, hard coating) so that they are prepared to better tolerate the cold. This process also stops any new, tender growth on plants.
Check your trees, shrubs and perennials in the fall and look for new shoots. If the new growth is light green and tender, starting on about Sept. 15, stop watering these plants and this will help the shoots of new growth to “harden off” or develop the tough layer that will protect them through the coming cold months.
Q: What plants can I use along with my mums for more fall color in my flower bed?
A: Asters are available now and can add shades of pink, cream and lavender to your beds. Ornamental cabbage or kale is another possibility. They come in colors of fuchsia, white, cream, pink, red and yellow with outer leaf edgings of green. Peacock varieties of kale have outer foliage that is almost feathery which will add interesting texture and color to fall flower beds.
September Tip: September is a great time to add top dressings (such as compost, manure, peat, etc.) to your soil but it is not the time to fertilize. Fertilizing will encourage new growth on plants that will be too weak to handle to winter weather ahead. Top dressing, on the other hand, will add nutrients to the soil that need the winter to break down and provide you with richer, more fertile soil for the plants that will need it in the spring.
If you have garden questions or tips for other gardeners, send them in to