Planted 6 different perennial hibiscus in my north facing front garden this year. We live in Guelph, Ontario and they are all still blooming today (October 10). We haven’t watered them in months and the drought and cold temps this past week hasn’t stopped them. Sure hope they will return hardy next season. Typically I cut everything back and remove all my annuals from my gardens by Thanksgiving but I decided to hold off another few weeks as they are still blooming so beautifully.
Thank you for contacting the Toronto Master Gardeners.
For many years, fall was the time of year when gardeners could be seen in their gardens busily cutting back their perennials and cleaning up every leaf that had fallen. Trust me, I used to be one of them. However, did you know that carrying out this fall cleanup is not only harmful to your shrubs and perennials but also does nothing to encourage and support wildlife?
Tall stems of perennials such as goldenrod, hyssop, black eyed Susan and coneflowers provide much needed carbohydrate packed seeds for overwintering birds. These tall stems not only provide a food source but catch the dying leaves and snow and thus provide a natural protection from the drying winter winds.
Leaves of low growing perennials such as daylilies, astilbes, and irises turn brown and cover the crown of the plants providing a natural mulch. This natural mulch not only protects against the cold, but also against the heaving of the soil caused by the alternating action of freezing and thawing. The foliage will rot away over the winter putting nutrients back into the soil, which saves you money, as well as providing homes to hundreds of insects and larvae that will become food for birds and many beneficial insects.
My suggestion would be to leave the hibiscus alone and enjoy their flowers until frost. Your garden will thank you and you get the added bonus of being able to sit back and enjoy the beauty of your fall/ winter garden.
There are a number of terrific articles on this topic,
Doesn’t Nature do Things Well, To Clean Up or Not to Clean Up, 6 Reasons not to Clean up your Garden this Fall, Messy is Beautiful, Why You Should Skip the Fall Cleanup
Lastly, you may wish to read the Toronto Master Gardeners Guide on Putting the Garden to Bed
Oct. 10, 2022