Waking Up the Garden
WAKING UP THE GARDEN IN SPRING
Late winter/spring cutting back and general maintenance to wake up the garden
Cut back all herbaceous foliage
- If a plant was disease-free and healthy the previous year, consider “chop and drop”, ie. cutting the foliage up into small pieces and using it as mulch at the base of the plant.
- Some perennials maintain a basal crown of foliage. Dead leaf as needed
Example: Burgundy leaf Heucheras
Evergreen perennials: two methods
- Iberis sempervirens (Candytuft) This plant has its buds set the previous fall for early spring bloom. Wait until flowering is finished to shape it or you will cut off last year’s flowers
- Helleborus (Hellebores, Winter and Lenten Rose) Most hellebores are semi-evergreen, completely evergreen in a mild winter. By spring, the old foliage usually shows winter damage. Cut all unsightly foliage to the base to make the current year’s foliage look fresh and attractive. Do this very early, BEFORE the flowers bloom.
- Bergenia is also semi-evergreen. Dead leaf the winter-damaged foliage. Be careful of the flower buds.
- Epimedium: some epimediums are semi-evergreen (E. versicolor, E. warleyensis, E. pinnatum ssp. colchicum, E. youngianum x ‘Roseum’: Be sure to cut back last year’s foliage in late March or early April to allow the flowers and young growth to appear. Otherwise the old foliage will mix in with the new growth, ruining the spring effect.
Tie up ornamental grasses first; cut down with electric hedge clippers or garden sickle
- Dead-leaf Festuca and Helictotrichon; never cut down completely (comb them out with your fingers)
- Liriope and Ophiopogon are difficult and leathery- may need to use blade on weed whacker or garden sickle. Even though “evergreen”, remove last year’s foliage to make current year’s foliage look fresher.
- Cut Carex grasses down in early spring before the flowers appear.
Perennials with a woody framework: cut back hard in early spring as soon as new growth breaks. Examples:
- Lavandula (Lavender) - cut to within 12” of the ground once new growth begins. Remove all old, woody stems.
- Ruta graveolens (Rue)-cut to within 12” of the ground. Remove old, woody stems and those growing horizontally.
- Teucrium chamaedrys (Germander)-can be sheared to 8-12”. Thin out old, woody stems.
- Perovskia (Russian Sage)- The first year, you must prune this plant to create a strong, woody framework. Otherwise, it will be long and sprawling. In the early spring of its second year, cut it back to a 12-15” low sub-shrub, creating a strong woody framework on which to grow a full and bushy plant.
- Artemesia ‘Powis Castle’- you must leave this plant untouched over the winter and cut it back hard, to within 4-12” of the ground, creating a woody framework, in early spring.
Summer blooming flowering shrubs used in the perennial garden (see pruning list) - as the new growth begins to break, cut back to a woody framework. Remove all dead and diseased wood. Examples include…
- Buddleia (Butterfly bush)- will grow 4-6 feet in one season. Can be cut to ground or cut to a woody framework at the height of your choice (if little winter dieback has occurred) to create a large, tree-like specimen.
- Caryopteris (Blue Mist Shrub) - will grow 2-3 feet in one season. Remove many of the older, woody branches to the base. Remove branches growing horizontally or that form weak crotches. Can be cut to
within 12” of the ground or to a woody framework at the height of your choice (if little winter dieback has occurred).
- Abelia grandiflora (Glossy Abelia) - can be cut to the ground or pruned back to a low woody framework at the height of your choice. Will grow 2-4 feet in one season.
- Hypericum (St. Johnswort)-Most St. Johnswort shrubs die to the down in the winter. Cut all foliage to the base and a new plant will regenerate and grow 2-4 feet in one season.
- Roses- Roses vary in their pruning techniques by classification. In general, in the spring take down the protective hills of topsoil/compost added the previous fall and spread it around the drip line of the plant. Remove all dead and crossing branches. Open up the inside of the plant by thinning out dense wood in the center. This increases air circulation. Shrub roses are pruned like other summer blooming shrubs. The severity of pruning is based on the overall size that you want the plant to attain in the coming growing season. Climbing roses are pruned to a woody framework and tied down to an appropriate support.
Thinning of new shoots: Phlox paniculata and Monarda (bee balm) are two plants that can be thinned in the early spring. Remove 1/3 of the new growing shoots to the base. This will encourage better air circulation, reduce fungus, and create fewer and larger flowers.
SPRINGTIME PREVENTATIVE MAINTENANCE FOR PERENNIALS
Clean up last year’s foliage to prevent the spread of disease. This includes foliage still on the plants as well as any dead foliage on the ground at the base of the plant. This is especially important for peonies (to prevent botrytis), roses (to reduce black spot), and anything else that was problematic last year.
If a plant was disease-free and healthy the previous year, consider “chop and drop”, ie. cutting the foliage up into small pieces and using it as mulch at the base of the plant.
Leave up 15” of dead stems on hollow-stemmed perennials such as milkweed, asters, Helianthus. This will provide nesting sites for tunnel nesting bees for the upcoming season. Don’t cut the tops off of these stems until the temperature stays at about 50 degrees for a week to protect the bees that are overwintering in the stems.
If your roses were badly infected with fungus last year, consider clean cultivation beneath them. Remove all of last year’s mulch and discard. After adding compost and fertilizer, keep the area below them clean, cultivating regularly. Although mulching is ideal, old mulch can harbor fungus spores that will splash up on the plants. Always open prune your roses in spring and again in mid-July.
If Japanese beetles were a problem last year, begin this year spreading granular grubGone. This will gradually reduce and eventually eliminate the Japanese beetle grub population. As soon as Japanese beetle season arrives, immediately spray the plants with Neem oil at dusk. This acts as an anti-feedant and makes the plants distasteful to Japanese beetles.
Hollyhocks are very susceptible to rust. Once rust is established in your garden, it can easily spread to New England asters. It is best to cull 2-4 year old hollyhock plants, removing them completely from the garden and regularly replacing them with young seedlings. Hollyhocks are technically biennials, but they actually live for many years. Older plants are weaker and much more susceptible to disease. If rust was a problem last year, you must keep your plants clean. Remove any infected leaves immediately. Spray with copper as soon as the leaves emerge to help prevent rust from reappearing and spreading.
Be sure to cut down all German or bearded iris foliage to the ground the minute you walk into your garden in the spring. You should NEVER leave it up during the winter as that is where the borer larvae overwinter. By simply eliminating the overwintering larvae, you will eliminate the problem without chemicals. If you suspect borers (watch for vertical tunnels in the foliage), squeeze the tunnels with your fingers. If you have a serious problem, mark on your calendar to divide 3-5 year old stands of bearded irises in August.
In an effort to provide horticultural information, these educational documents are written by Nancy DuBrule-Clemente and are the property of Natureworks Horticultural Services, LLC. You are granted permission to print/photocopy this educational information free of charge as long as you clearly show that these are Natureworks documents.