Gardening Sweet Spots
By Donna Hessel
Hopefully, your gardens and planted containers flourished over the summer, you’ve enjoyed a bounty of veggies that are now frozen or canned and colorful bouquets of flowers to decorate your home. It’s time to put your garden to bed for winter, so come spring, it will be ready for you to plant and enjoy, once again.
Let’s Start with Perennials
Perennials are plants that come back every year. Fall is the best time to divide perennials that bloom in the spring and early summer. Wait until spring to divide any perennials that bloom in the late summer and fall. Leave ornamental grasses and selected perennials standing to provide food and shelter for wildlife, as well as provide winter interest in the garden.
Mulch cut perennials with chopped leaves or other mulching material. Branches from pine trees or from a live Christmas tree make great covers for daylilies. The branches will keep the roots from heaving in freeze/thaw conditions and keep deer from nibbling at new shoots in the spring. If you grow roses, plan to prune them in the spring, not now. Stop using fertilizer six weeks before a frost, allowing dead flowers to go to seed. Remove any dead or diseased leaves and trash them. Cover the base of the bush with some extra topsoil and cover the base with mulch after the ground is frozen.
There is some controversy as to whether to cut back perennials in the fall or leave them standing until spring. There are pros and cons for both positions:
Reasons to Cut Back Perennials:
- Decreases the incidence of disease and pest infestation in susceptible plants (especially ones that are already affected).
- Reduces garden chores in spring.
- For plants with no winter interest, your garden looks tidier.
Reasons NOT to Cut Back Perennials in Fall:
- Dead foliage protects crowns, especially tender plants.
- Removes seeds for birds.
- Removes habitat for beneficial insects.
- Many plants have winter interest, especially with snow cover.
- Leaving a few inches of old stems can help mark the spot for perennials that emerge late in spring.
- Landscape services often don’t know the difference between your plants and weeds in the spring. Remaining foliage can be a clue that it’s a desirable plant.
These pros and cons are from an excellent article in the Garden Artisans (nursery catalog) online newsletter by Kerry Kelly that also detailed how to treat specific perennials in the fall. Most of us grow at least some of these, so take advantage of the author’s expertise when you are cleaning up your gardens.
Cut back to 1 inch:
- Bee Balm (Monarda): if powdery mildew is present.
- Brunnera: no winter interest.
- Daylily: over-accumulation of old foliage weakens the plant.
- Hosta: turns slimy over winter; harbors slugs.
- German Iris: leave a 2-inch fan of foliage—prevents borers (never mulch over rhizomes); divide by early fall.
- Peony: to prevent foliar and flower disease (mulching too heavily will prevent blooming); divide by early fall.
- Tall Garden Phlox: if powdery mildew is present (no winter interest).
- Pulmonaria: if mildewed.
- Veronica: no winter interest.
Leave new fall basal foliage, but cut old stems:
- Asters
- Meadow Sage (Salvia ‘May Night’ and similar)
- Penstemon
- Pincushion flower (Scabiosa)
- Shasta Daisy (Leucanthemum)
- Yarrow (Achillea)
Do not cut back in fall and why:
- Agastache: protects crown
- Annuals such as cleome, cosmos, marigold, zinnia: if you want them to re-seed (or first harvest the seed heads once mature)
- Avens (Geum): (semi-)evergreen foliage
- Baptisia: interesting seed heads
- Bergenia: evergreen foliage
- Black-Eyed Susan (Rudbeckia): seeds for birds
- Bugleweed (Ajuga): evergreen foliage
- Chrysanthemum: protects crown
- Coneflower (Echinacea): seeds for birds
- Coreopsis: seeds for birds
- Coral Bells (Heuchera): evergreen foliage — tidy it up in spring
- Dianthus: evergreen foliage
- Epimedium: evergreen foliage — tidy it up in spring
- Ferns: Autumn, Christmas, Holly, Tassel and other evergreen ferns: tidy up in spring
- Hardy geraniums: (semi-)evergreen foliage–sprawling ones can be cut back after first bloom as needed
- Hardy hibiscus: overwintering/nesting site for pollinators
- Hellebores: evergreen foliage–tidy up in spring
- Herbs: with (semi-)evergreen foliage: thyme, oregano, sage, burnet, tarragon, rosemary–can be cut back by 1/3 to 1/2 in spring
- Gayfeather (Liatris): seeds for birds
- Hens and Chicks (Sempervivum): evergreen — remove browned leaves
- Lamium: (semi-)evergreen foliage (unless disease is present)
- Lavender: evergreen foliage — yearly spring pruning will keep it from getting woody: never cut back into old wood!
- Montauk daisy: protects crown
- Ornamental Grasses: winter interest, seeds/protection/nesting material for birds, overwintering site for pollinators and beneficial insects
- Oxeye Sunflower (Heliopsis): seeds for birds
- Moss Phlox: evergreen foliage–tidy after bloom in spring.
- Oriental Poppies: plants have come out of summer dormancy–fall foliage is new; divide by early fall
- Red hot poker (Kniphofia): protects crown
- Sea Holly (Eryngium): interesting seed heads
- Sedum: upright varieties have good winter interest; many low-growing types are evergreen
PLANT SEEDS IN FALL
There are a lot of perennial seeds that can be planted in the fall to sprout the following spring. In cold-winter areas, plant seeds at the depth given on the package instructions after a killing frost but before the ground freezes.
The goal for planting in fall is not to have your seeds germinate but to give them a period of stratification, exposing them to cold and moist conditions. The alternating freeze and thaw of winter helps break down the seed coat and starts the growing process. Not all perennials do well with this technique, though. Check the list below for seeds you can sow in fall.
Perennial seeds to plant in fall
- Black-eyed Susan Rudbeckia fulgida
- Penstemon Penstemon spp. and hybrids
- Perennial geranium Geranium spp. and hybrids
- Perennial sunflower Helianthus spp. and hybrids
- Pincushion flower Scabiosa spp. and hybrids
- Prairie coneflower Ratibida spp.
- Purple coneflower Echinacea purpurea
- Wild columbine Aquilegia Canadensis
BID FAREWELL TO ANNUALS
Most annuals should be removed and added to your compost pile or trashed after the first frost has flattened them. You may want to try to overwinter some plants marked “tender perennials” in the house near a sunny window or under grow lights. Add a layer of compost to your garden now and it will enrich the soil for planting in the spring.
CARE FOR TREES AND SHRUBS
Burlap attached to stakes surrounding shrubs such as hydrangeas will discourage deer from nibbling on them. Spraying broadleaf evergreen shrubs such as rhododendrons with an antidessicant (e.g., Wilt Pruf) after a hard frost will protect them from losing moisture. Wrap trunks of trees, especially young trees, with tree-wrap paper or mesh trunk protectors to keep rabbits away and deer from rubbing their antlers off on trunks. Rake leaves and use them for mulch on your gardens or add them to your compost pile.
Fall is not the time to prune trees and shrubs because the typical plant response to pruning is a stimulation of growth. The best time to prune is when the plants are totally dormant for the winter — the end of December or the first of January. Pruning can be postponed until March before new growth emerges.
PLANT SOME BULBS FOR SPRING COLOR
Early November is an ideal time to plant spring-blooming bulbs to give them time to establish roots before a hard frost. The deer won’t bother daffodils. If you love the tulips the deer love too, plant the bulbs in a container and overwinter them in a cold garage, watering occasionally. Set the pots on a deck or other area deer don’t visit when shoots appear, and enjoy tulips in the spring.
PROVIDE SOME TLC FOR YOUR TOOLS
After you’ve finished all those fall chores, take a look at your garden tools. They need to be cleaned and sharpened, rubbed with vegetable or canola oil and stored for winter so they will be ready to use when you get that first urge to get out and plant next spring. Clean and sharpen mower blades; drain gasoline from the mower. Drain and store hoses. Drain the irrigation system if you have one and turn off water valves to outside faucets or insulate them to prevent frozen lines.
Got all of that handled? Congratulations! Now you can curl up with a good book or enjoy your favorite hobby without any regret about those fall gardening chores left undone!
All photos by Donna Hessel
