Some perennial flowers and grasses need to have the assistance of their wilted summer foliage to use for winter protection and insulation from the cold wet weather.
Many need the protection for the many drab rainy months of a temperate climate. These ones listed below prefer to be cut back in the spring for this reason.
It’s not the end of the world if you cut something at the wrong time of the year, most plants can handle that and will recover. You may lose some of the more sensitive varieties though. I’ve included the zone range for these plants as well.
I’ve included links to more details about each plant and the option to purchase live plants where possible.
In a lot of cases, I prefer buying young plants rather than seeds, it cuts out a lot of time and fuss.
Artemesia – Trim in early spring. The new growth that results due to a fall prune is too tender to survive the winter and the cold is often enough to kill the whole plant. Zone 5-9
Aster – Fall blooming asters usually have been pinched a lot during the growing season. They like to rest once they are allowed to bloom. This is why they like to be pruned in spring. Zone 4-8
Astilbe – This plant likes to use it’s dead foliage to insulate it through the winter. In the spring, it’s easy to rake away the loose fall debris to allow new growth to emerge. Zone 3-8
Balloon Flower (Platycodon) – The Balloon flower blooms until frost and remains attractive for a long time. The new sprouts will arrive late in the spring so it helps to leave last years foliage in place until then so their place is marked. Zone 3-8
Bear’s Breeches (Acanthus) –Cut back the leaves as they turn yellow and become unattractive. Leave the latest ones on as they should remain evergreen throughout the winter. Trim back in spring to allow new growth to emerge. Zone 6-10
Black-eyed Susan (Rudbeckia) – If you can tolerate the site of this perennial in the winter then leave the stalks standing in the fall and the seed heads will feed the birds in the winter. Zone 3-9
Bleeding Heart (Dicentra) – In the fall the foliage will turn yellow and die back completely like a Hosta. No pruning is really needed in the spring as there will likely be nothing there. Zone 3-9
Butterfly Bush (Buddleia) – If you prune this one the fall then you greatly increase the chances of it dying over the winter. Leave it as is until signs of new growth show in the spring and then cit it back to 8″ to 12″ tall. Zone 6-9
Butterfly Weed (Asclepias tuberosa) – This plant is a prolific self-seeder and should be deadheaded in the fall if dozens of new plants would be unwelcome in the spring. Leave the seed heads on to feed the birds through the winter if you wish. Zone 4-9
Campanula -Cherry Bells This one gets cut back in the spring to clean up unsightly or damaged foliage and to encourage more blooms. Fresh basal foliage will result. This should be left on the plant through winter, so as not to encourage more tender growth in the fall. Zone 3-8
Cardinal Flower (Lobelia cardinalis) – The beautiful Lobelia likes evenly moist soil, but doesn’t like living in cold, wet soil for the months of winter. When you leave the foliage and flower stems in tact it protects the plant from the stresses of winter and possible crown rot from too much rain. Clean up in the spring when the wet weather comes to an end. May or may not survive. Zone 3-9
Chrysanthemum – The foliage is critical in order to protect the crown over winter, but prone to mildew. Zone 5-9
Coral Bells (Heuchera) – Palace Purple This plant is susceptible to the freezing and thawing of a temperate climate. It’s recommended to leave the foliage in tact to act as a mulch to protect them through winter. Zone 4-9
Cushion Spurge – Prune back to its base in the spring, that’s it. Zone 4-8
Delphinium – Cut back the flower stalks in fall, but allow the foliage to stay on until spring. Cut back before new growth emerges. Zone 3-8
Dianthus (Sweet William) – Most varieties will remain evergreen, so just give it minimal clean-up in the spring as needed. Zone 5-8
Gayfeather (Liatris spicata) – This one doesn’t like wet feet and can rot. The seed heads provide food for the birds over winter, but the plant may die. Zone 3-9
Goldenrod – The new hybrid goldenrod doesn’t seed all over the garden and can be left standing for the winter. The species “Solidago” should be cut in fall to avoid becoming invasive. Zone 2-8
Lamb’s Ear (Stachys) – Let the leaves stay and remove winter damage when the 
leaves sprout again in the spring. Lamb’s Ear is very invasive in temperate climates. Zone 4-8
Lavender – Lavender doesn’t like to be cold and wet and easily dies over the winter. Fall foliage protects it a bit so if it survives cut it back in the spring when new growth appears. Zone 5-9
Lavender Cotton – Doesn’t like the cold. Don’t prune after middle of August. Wait until you see new growth in the spring before pruning again. Zone 6-8
Lupin – Lupins cannot stand very much, they are not hardy. It’s best to treat them as an annual in most locations, but if not cut it back after the flowers fade, leave the greens on until spring. they are susceptible to mildew. Zone 4-6
Oriental Poppy – Scarlet Red and Royal Wedding. Cut back flower stalks after they fade in fall, but leave the foliage to protect the crown over winter. Zone 3-7
Coneflower (Echinacea) – This perennial doesn’t look very attractive in the winter, but if you leave the stalks standing the seed heads will feed the birds. Zone 3-8
Red-Hot Poker (Kniphofia) – This one is also very sensitive to wet and can easily rot. Cut the green back by half and the rest will help to protect the crown. Zone 5-9
Russian Sage (Perovskia) – Treat the same as Lavender. Prune back any dead woody branches to the ground. Zone 5-9
Sea Lavender (Statice)- Cut back dead foliage in spring Zone 3-9
Sea Holly – Cut back once per year in August or September only and the new basal growth is enough to get the plants through winter. Zone 3-8
Sedum (Stonecrop) – Prune in very early spring only if needed Zone 3-10
