What to Do With Hostas in October? After its flowers fade and its sensational leaves shrivel, a hosta (Hosta spp.) has finished its annual cycle of growth, flowering and seed production. Late-flowering hostas finish their show in August, and by October most hostas look pretty pitiful. Use the month of October to tidy up the garden and prepare your hostas for the chilling months.
Hosta Basics Hostas are herbaceous perennials grown in China, Japan and Korea before they were imported by Europeans in the 18th century. In the U.S., they grow throughout the East, Midwest and Upper South; hybrid forms are hardy over a range of U.S. Department of Agriculture zones 3 to 9. Hostas in Northern California succeed in woodland gardens where they are protected by a layer of mulch and their soil is amended with organic matter and sulfur to bring its pH level down to 6.0 to 6.5.
Remove Scapes If your hostas are still nice and green in October, help them stay green by removing parts of the plant that compete with leaves for nutrients. Remove the plants’ numerous flower scapes -- long, arching branches that hold blooms during the summer -- unless you intend to ripen the seeds that form on them. Cut as far down into the crown as possible on the scape, taking care to avoid cutting into the tender centers that will produce next season’s first leaves.
Late Season Care In a Mediterranean climate, hostas remain green and keep growing longer than in areas where frosty nights begin in October. Allow your hostas to continue to grace your garden as long as the weather stays warm -- but remove leaves that turn brown or dry out around the edges during autumn’s dry weather. Remove leaves decimated by slugs or other pests, too -- taking older leaves from around the outside of the crown, leaving more moisture and nutrients for newer, inner leaves. Do not fertilize hostas after August 1, but continue to give them an inch of water weekly, gradually reducing the amount of water given. Over-watering may lead to root rot or a burst of new, tender growth that makes the plant vulnerable to frosts, so don’t water them as they prepare for dormancy in late September and early October.
At some point, your hostas will give up for the season and all of their leaves will collapse in a yellowish heap. In USDA zones 4 and 5, frost usually kills back hostas, but in warmer zones they will go dormant on their own schedule, giving up the ghost anytime from October through November in preparation for their required winter chilling period. If your plants enter dormancy in October, trim them off, leaving 2 to 3 inches of stalk standing above the surface of the soil to keep the plant’s circulatory system clear of soil-borne fungi. Remove the dead leaves, not only for appearances’ sake, but also to deny shelter to rodents, insects and pathogens looking for a place to stay warm through the holidays.
’In Minnesota, we have divided plants in October and replanted successfully. Many gardeners advise not transplanting 6 weeks before the first frost.
Since you do not know the amount of winter snowcover and moisture your hostas will receive the following winter, it is a good idea to water your gardens thoroughly in the fall.
If your garden is dry during the winter due to lack of snow cover, severe wind, or an exposed slope, you may have stunted hostas the following year.
We cut our hostas right to the ground with bread knives (disinfecting our knives in 10 to 20% bleach solution after every cutting) each fall and remove the dead leaves to reduce the risk of spreading diseases and the proliferation of slugs and other pests.
Slugs produce many eggs in the fall, so it is also a good time to apply slug killer.