Fall perennial care
Fall is a busy time in my garden, with lots of clean up and planting for next season to get done. We typically have around 6-7000 tulip bulbs to plant, plus other bulbs like alliums, and usually a few new peonies too. While it’s exciting to think about the new flowers that will come from these investments, my garden is full of existing plants that need attention too each fall. I’m talking about the perennials that make up the backbone of my garden. I rely on these plants to provide a steady stream of blooms from late May until early September each year. They fill such an important role on my farm, bridging the gap between early bulbs and summer annuals, and then again in late summer and early fall when many of the tender annual flowers have died due to frost. They are true workhorses in my garden, so they deserve extra care before they go dormant over the winter.
Here are the steps I take to make sure my precious perennials stay healthy:
1) Water, water, water. We have been experiencing drought the last two years, which really weakens plants, shrubs and trees. Plants that go into winter in a stressed state due to drought are much more likely to die from winter kill. It’s easy to underestimate how much moisture a mature shrub or plant needs. They have extensive root systems that require a lot of water. If there is a lot of rain in September and October, you can feel assured that your plants will be okay for moisture. Unfortunately, that is not the way the climate is trending these days. That means you most likely need to water throughout the summer and especially before the ground freezes. The amount of water you need to apply will depend on the type of soil you have, but you need to water until the top six to nine inches of soil is water under your plants feels wet. In my garden, I’ve gone planting after what I thought was a good rain, only to find the soil dry an inch down. It takes a lot of water to give the root zone a good soak and the only way to know is to get out your trowel and dig down near your plants and check the soil.
2) Check for disease. Go through your garden and check all your trees, shrubs and perennials for signs of viruses, damaged limbs and pest problems. This is so much easier once the leaves have fallen. Prune branches and sterilize clippers in between cuts if you see black knot or other fungal disease on shrubs. Dig up and put diseased perennials in the trash, never in city or home compost. I have some peonies with Tobacco Rattle Virus that appeared this year, after 4 years of tending them from new plants. It’s really disheartening to throw away plants, but if you don’t, you risk the virus or disease spreading to your whole garden.
3) Move and/or divide perennials. If you have plants that are at least three years old and have never bloomed or are under performing in other ways, consider whether you’ve given them the best place to thrive. A plant that requires semi shade may have been able to cope with full sun in years past, but not with the increasing heat of our summers. Check online to see how much sun, moisture and drainage your plant requires and move it to a better spot in the garden. Really mature perennials do need to be divided to keep them healthy as they will outgrow the space you’ve given them and start to die off. Peonies should be divided every 10-15 years. September is the best time to do this as night time temperatures have cooled and with good watering or rain, perennials will transplant well. Cut back foliage before moving so the plant can focus it’s energy on root growth, not maintaing green growth. If you don’t get around to it until October, don’t stress! I have planted until late October with good results still.
4) Once you’ve got everything in it’s new spot, give all your perennials a top dressing of fresh compost and some organic granular fertilizer. This will set your plants up for good growth in the spring once the snow melts. It’s also one less thing to worry about in the busy spring season, knowing your perennials are set for another season.
5) If you have plants that are not quite hardy to your growing zone, the last task you need to do before the ground freezes is give them some extra winter protection. In early November, just as the night time temperatures start to seriously drop, I give things like lavender and my cloned echinacea a thick layer of barley straw or spruce branches to form a blanket. Use whatever organic mulch you have on hand, as long as it can be easily removed in spring when the soil warms. This is really important in years when we don’t get adequate snow fall in winter, or when it all melts during a warm spell, leaving your plants exposed to the next cold snap.
You’ll notice I didn’t mention cutting back perennials in fall. That’s because I don’t! Any branches I haven’t harvested for dried flowers, I leave on the plant. The stems serve as important winter shelter for lady bugs and other beneficial insects. The base of leaves help catch and keep snowfall, protecting the roots. I wait until the nighttime temperatures are staying above 10C in spring before I go around and clean up last years growth. Then I know it’s warm enough for our insect and pollinator friends and I’m not disturbing their winter sleep.