It is the perfect time to do fall container plantings. While the basics of design and care don’t really change for fall, there are a few things that need to be taken into consideration.
Choosing Plants: In spring, you are likely choosing plants for their ability to withstand summer heat conditions. When choosing plants for fall, their ability to withstand cool temperatures is key to keeping your containers looking great for months. Another trait to consider is the ability of the plants to bloom under shorter day lengths. Fall is a great time to look to foliage for color. There are many plants with foliage that are now colorful when the temperatures are cool. Heucheras (Coral Bells), asters, and most ornamental grasses are good examples. Foliage also adds color without the need for flowers. Coleus and Sweet Potato Vines have great color for fall and seem to make perfect sense; however, neither of them is at all frost tolerant. They will curl up and die if temperatures get even close to freezing; therefore, they are not good choices for fall containers. For us, pansies, violas, and ornamental kales and cabbages are always good container plantings for fall. Also try ornamental peppers, native sunflowers, golden rods, celosias, and ornamental grasses. Take a nature walk and collect wildflowers, grasses, acorns, twigs, and grapevines to go with the usual pumpkins, gourds, and corn stalks to make your outdoor decorating interesting and beautiful.
Planting: When potting up planters in spring, there are advantages to using fewer plants per container and leaving those plants plenty of room to grow all summer. While you are likely planting your fall containers while the temperatures are still quite warm, those temperatures are going to quickly begin cooling off. As temperatures cool, plant growth slows or stops completely. This means that plants potted up in the fall aren’t going to show the amazing growth you get from those planted in spring. Fall is the time to stuff your pots full of plants because however full the container looks when you plant it, is pretty close to how full it will look all fall. This also applies to plants you put into the ground for fall color, so plant the pansies, violas, cabbages, and kales close together.
Watering: Just as cooler temperatures of fall mean less plant growth; it also means less water is needed. The deeper into the fall you go, the less often you will need to water, and that’s a good thing! You still need to water some all winter if it doesn’t rain.
Fertilizing: Fertilization is also different in fall and is probably not even necessary. If you do feel that the fertilizer would be helpful to your plants, an application of water-soluble fertilizer in the form of fish emulsion, seaweed extract, or compost or manure tea will be more effective than time-release fertilizers that are formulated to work with warmer soil temperatures.
Frost Protection: While choosing frost-tolerant plants is necessary, you might also want to add an extra level of protection for your plants when night temps get below 40 degrees. Often, we have an early frost in Oklahoma and then several weeks of Indian Summer that are perfect for plants and gardeners. You can use old sheets or row-cover fabric to get your plants through a few nights of temporary cool temperatures. Placing containers together near the house also provides more protection from cold.
Switch-Outs: If you use heavy decorative containers for your plants, such as ceramic or concrete, adding new soil for planting is a lot of work. One way to make planting easier is to use lightweight plastic containers that are the right size and shape so you can plant the plastic container and then just drop it inside your decorative container. When you want to replant, simply pull out the plastic container, compost the plants, refill and replant the plastic container and drop it back into the decorative planter. You can also plant a plastic container ahead of time, and have it ready to go when you are. Happy Fall Container Gardening!