Maintaining Your Garden

Perennials

Many native perennials (but not all) prefer acidic soil. Have a soil test done through your local state extension service to see if you have the ideal conditions for the perennial you are looking for:

Pennsylvania: http://agsci.psu.edu/aasl/soil-testing/soil-fertility-testing
New Jersey: https://njaes.rutgers.edu/soiltestinglab/
Delaware: http://extension.udel.edu/dstp/
New York: http://soilhealth.cals.cornell.edu/

Good drainage is very important, so adding organic humus or compost to your soil throughout the year will help strengthen your plants.

Pennsylvania: http://extension.psu.edu/plants/gardening/composting
New Jersey: http://njaes.rutgers.edu/pubs/fs811/
Delaware: http://extension.udel.edu/factsheets/yard-waste-and-composting/
New York: http://gardening.cals.cornell.edu/garden-guidance/composting/

Consider using a plant stake to mark where a new perennial has been placed. Some are slow to emerge after winter.

In March, look for winter injury. Reset perennials that were heaved by frost.

In April, divide late blooming perennials. In general, perennials can be transplanted or divided at this time, when they are only a few inches high. Transplant early blooming ephemerals as soon as they finish blooming.

In May, prune fall blooming natives, such as New England aster and goldenrod. Late in the month, cut each stem one-half to two-thirds off. Each cut plant stem sends up two new shoots where it has been cut and becomes bushier! Once you perform this “haircut,” let the clippings lay at the base of the plant. That way, a caterpillar may crawl back up to healthy growth.

In June, watch plants in the mint family (e.g. Monarda, Agastache), for damage done by the colorful 4-lines plant bug; leaves show brown spots, then round holes. Nymphs are active in April and May. In June and July adults lay eggs in the stems. This doesn’t represent a serious infection, nothing can be done about this and it poses no serious problem for the plant. Also, near the end of June, watch for Japanese beetles. The best remedy: early in the morning, while beetles are inactive, pick them off and drop them into a bucket of soapy water.

In July, early in the month, cut back some of the new growth on tall summer blooming plants such as Culver’s root, ironweed, Joe-Pye weed, sneezeweed, blue vervain and boneset. Do a second cut on fall blooming natives, such as New England asters and goldenrod. Consider cutting the many stems in your plant different lengths, leaving those at the back with longer stems. This way, your plant stems will bloom at different heights. Also, watch for heat and drought stress in July, but do not overwater. The best time to water is very early in the morning.

In August, watch for powdery mildew (often seen on phlox). Prune and dispose of diseased and dead parts. Space plants for good air circulation and don’t plant phlox in damp, shady locations.

In September, do more transplanting.

Why transplant or divide and transplant?

To reduce overcrowding. For example, if your bee balm (Monarda sp.) is spreading into the phlox (Phlox sp.)
To allow better air circulation in order to reduce powdery mildew (see above)
To introduce a favorite plant to a new planting area
To share with a fellow plant enthusiast.

Dividing and transplanting has a rejuvenating effect on many perennials. Many offsets display more vigor than the parent plant. This propagation method can also be used to replace a tired original.

Deadheading throughout the growing season:

If you cut off blossoms as they fade, many plants will put energy into making more blossoms (e.g., phlox (Phlox sp.) and bee balm (Monarda sp.)). The goal of the plant is to have the blossoms pollinated so that seed will be formed and the plant can reproduce. But keep in mind that the seeds of many plants (e.g., purple coneflowers) are both attractive in the winter and important for wildlife, so consider leaving some of the “dead heads.”

Before planting, consider the growth style of each the plant. Some plants are clump forming (e.g., Asclepias incarnata) and others spread very aggressively by extending roots outward (e.g., Asclepias syriaca). Caveat emptor.

Trees and Shrubs

Most native trees and shrubs prefer acidic soil. Have a soil test done through your local state extension service to see if you have the ideal conditions:

Good drainage is very important, so adding organic humus or compost to your soil throughout the year will help strengthen your trees and shrubs.

Ideally, trees and shrubs should be planted in March (as soil becomes workable), April, September or October. The new plantings need to be adequately watered—feel the soil to test its moisture level. Evergreens do best when planted in early September and should be watered until the ground freezes.

However, transplanting from a container can be done at any time from March through mid-October, as there is little root pruning or disturbance involved. The plants would be only too happy to get out of the pot and into the ground. If planting is done in mid-summer, additional watering may be necessary to help establish the plant.

To protect your new plantings from browsing deer, surround your plants with wire fencing or rebar. To know which plants to protect, look for signs of wildlife damage in March.

Consider using leaves chopped with your lawn mower for mulch. Leaves are nature's fertilizer. Leaf mulch can be purchased in bulk from local companies, and many townships provide their mulched leaves for free. Be careful if you use commercial mulch. Keep it away from the trunk, as voles live under mulch and can cause damage in the winter. If all of the bark is eaten around the base, the plant will die.

March is the time for pruning trees and shrubs that do not flower in the spring. Prune flowering shrubs throughout the year, after their flowers have faded. Also prune any dead wood on trees, shrubs and vines.

Eastern Red Cedar, if planted near a plant in the apple family, may have a fungus called cedar apple rust. Look for and remove the orange rust galls if they appear.

Do not prune or fertilize after July 15. Pruning stimulates growth, which may not be advantageous when water is scarce and temperatures are high.

Recommended Books:*

Birdseye, Clarence and Eleanor G.
Growing Woodland Plants, Dover, c.1951

Brooklyn Botanic Garden
Gardening with Wildflowers and Native Plants, Brooklyn Botanic Garden Record, 1990

Cullina, William
The New England Wildflower Society Guide to Growing and Propagating Wildflowers of the Unites States and Canada, Houghton Mifflin, 2000

DiSabato-August, Tracy
The Well-Tended Perennial Garden: Planting and Pruning Techniques, Timber Press, 1998

Tallamy, Douglas
Bringing Nature Home: How Native Plants Sustain Wildlife in Our Gardens, Timber Press, 2007
Website: http://www.bringingnaturehome.net/what-to-plant.html.

*Some of these titles may be available at the Twinleaf Book & Gift Shop. Call ahead to confirm: 215.862.2914.

Grow Native Plants

Garden with Natives