Waking up the Garden in Spring: An Ecological Approach

WAKING UP THE GARDEN IN SPRING: An Ecological Approach

This is our recently revised handout on waking up the garden using methods that support life in the soil, pollinators, and soil fertility.

Late winter/spring cutting back and general maintenance to wake up the garden 

Reset the crowns of any perennials that have heaved (lifted) out of the ground

• The first thing you should do when you go out to your garden in spring is look for plants that have heaved up and reset them.

Cut back herbaceous foliage (herbaceous means leaves that die during the winter)

• Clean up last year’s foliage. 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”, i.e.. 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 (cut out dead leaves) as needed

Example: Burgundy leaf Heucheras

• Leave up at least 15” of dead stems on hollow-stemmed perennials such as milkweed, asters, ironweeds, Joe Pye weed, and Helianthus. This will provide nesting sites for tunnel nesting bees for the upcoming season.

Evergreen perennials Many perennials keep their leaves (especially their basal leaves close to the ground) throughout the winter. In the spring, if the leaves look ragged, cut out or comb out the bad leaves, leaving the rest.

Examples include:

• 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 the flower buds!
• Hellebores (Helleborus) Most hellebores are semi-evergreen. By the time late winter comes, the leaves should be removed right down the base. Do this BEFORE flower buds appear. Even if the old foliage doesn’t look really bad, cut it off anyway. The new growth is much healthier, shiny, and bright green.

• Epimediums: most epimediums are semi-evergreen. 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.
• Stachys byzantine (lamb’s ears) The fuzzy leaves of lamb’s ears should be raked out and the long rhizomes (stems along the ground) should be cut back to encourage new growth.

Tie up ornamental grasses first; cut down with battery powered 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:

• Lavender, rue, and germander (Teucrium) are examples. Cut to within 12” of the ground once new growth begins. Remove all 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. Thin out any thick, old woody stems each spring.

Summer blooming flowering shrubs bloom on new or currant year’s wood. As the new growth begins to break in April and very early May, cut back to a woody framework. Remove all dead and diseased wood. Remove crossing wood. Thin out older wood to encourage young, healthy new growth. Each shrub is treated a bit differently, but it is important to get them pruned in the early spring for the best flowering and berry set.

The list of summer blooming flowering shrubs includes: Abelia, Baccharis, Buddleia, Callicarpa, Cephalanthus, Clethra, Cornus (twiggy dogwoods, new name Swida), Heptacodium, Hibiscus syriacus, Hydragea arborescens, Hydrangea paniculata, Hypericum, Itea, Indigofera, Lagerstroemia, Lespedeza, Potentilla, Roses, summer blooming Spireas, Symphoricarpos, Vitex.

A few specific shrubs as examples:

• Buddleia (Butterfly bush)- a full size butterfly bush will grow 4-6 feet in one season. It 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. Dwarf butterfly bushes can be cut back to within 6” of the ground.
• Hypericum (St. Johnswort)-Most St. Johnswort shrubs die back in the winter. For Hypericum ‘Hidecote’, cut all foliage to the base and a new plant will regenerate and grow 2-4 feet in one season. For more upright, shrubby Hypericums, cut at least in half and remove all old or dead wood.
• Hydrangea paniculata- panicle hydrangeas bloom on currant year’s wood. They should be pruned each spring, removing long shoots and gradually developing a strong, woody framework of a main trunk (or trunks) and side branches.

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

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 dig out old hollyhock plants (3-4 years old), 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.

WHAT ABOUT THE LEAVES?

Whenever possible, leave the leaves in the garden beds. They are home to myriad creatures including the larval stages of many butterflies and native insects. You can mulch right over a thin layer of decomposing leaves or, if there are enough leaves, you can skip mulching all together. As the leaves break down, they feed the soil. If you are adding compost and organic fertilizer to the garden beds, you can do so right on top of the leaves.

If leaves are so thick that they are covering the crowns of the plants or preventing early spring bulbs or early perennials from emerging, then gently rake them off. If at all possible add them to a compost pile or re-use them somewhere on the your property.