For most perennials, whether you cut them back in the fall versus spring is completely up to you. Before you start, determine which season gives you more time for working in the garden. Also consider what may provide winter interest: many taller grasses or perennials with seed heads atop sturdy stems can look very attractive with frost/snow on them, and even provide a place for wildlife, like birds, to rest.
Take note or mark what plants may need to be divided or moved, as spring is typically the best time to do this (divide and/or move in early spring once plants start to emerge, but before they grow too lush). If you choose to cut back some plants in the spring, remember to get to them before they start to grow.
Certain perennials, like perennial Hibiscus (Rose Mallow) and shrubs like Buddleia (Butterfly Bush), are best when cut back to about 2 feet in height in the fall, followed by removing the dead growth in the late spring once they start to bud. Remember that these varieties are very late to start growing; it could be almost mid-June before they start to emerge.
Evergreen perennials do NOT need to be pruned in the fall. Plants such as Heuchera (Coral Bells), Lavender, Bergenia, Pachysandra (Japanese Spurge), Vinca (Periwinkle) and many rockery plants are best left alone until spring when you can remove any dead growth and prune to shape.
□ Mulch around any tender plants.
□ Wrap cold-sensitive shrubs with burlap.
□ Pull out annuals.
□ Plant fall bulbs like Tulips and Daffodils for spring colour. Apply blood meal or Hen manure to protect the bulbs from squirrels.
□ Empty annual planter pots and protect any frost-sensitive pots from the elements.
□ Prepare decorative pots for winter decor.
□ Move any frost-sensitive statues into an unheated shed or garage; or cover them for protection.
□ Rake leaves from lawn. (Maybe jump in the pile for fun!)
□ Harvest all your produce from your vegetable gardens. Enjoy all your hard work!
Late Winter / Early Spring Tasks:
□ Prune Evergreen shrubs (up to one third off) to shape.
□ Treat fruit trees with a dormant oil spray kit, just before they leaf out.
□ Empty your winter greens pots and prepare for early spring crops like Pansies and Violas!
□ Clean up Evergreen perennials by removing dead pieces and pruning to shape.
□ Add slow release fertilizer to perennial garden beds, such as bone meal, perennial food or garden food.
□ Prepare gardens for planting annuals and vegetables. Add compost, manure or 3-way mix to top up your beds.
□ Rake lawn to remove winter debris. Prune any broken branches on trees and shrubs from winter damage.
□ Make notes of empty spots in your garden that can be filled with new plants!
Either Spring or Fall Tasks:
□ Cut back and clean up perennial gardens.
□ Mulch to retain moisture and reduce weed growth.
□ Remove annuals or vegetable plants to prepare for planting new ones!
□ Top seed your lawn if needed.
□ Remove weeds – stay on top of weeds before they get overgrown. This will allow your plants to receive adequate light and nutrients.
□ Plan and create new gardens!