University of Vermont
Department of Plant and Soil Science

gmg logo   Spring News Articleline

RECYCLING COFFEE WASTES AND OTHER MAY GARDENING TIPS

Leonard Perry, UVM Horticulturist
and Charlie Nardozzi, Garden Consultant

Recycling coffee wastes, waiting to move spring-flowering bulbs, and getting rid of tent caterpillars in fruit trees are some of the gardening activities for this month.

Coffee grounds contain some major nutrients (nitrogen, phosphorus, and potassium) as well as some micronutrients, so put them to work in your garden. Allow them to dry and then spread them around the base of plants. Lettuce, especially, seems to benefit, and the grounds may benefit acid-loving plants since the grounds are slightly acidic.  Coffee grounds also will deter slugs.  Slit coffee filters and place them around the base of hosta stems, or scatter the coffee grounds, if slugs are a problem. 

If you want to move some spring-blooming bulbs to another spot, or thin thick clumps of daffodils, wait until the foliage has turned yellow later in summer, then carefully dig them up and let them dry in a shady spot for a few days. Store the bulbs in a cool, dry place for the summer until it's time to plant them in fall.

If you haven’t planted containers yet, consider adding a water absorbing product (sold as this in garden stores) to the soil first.  You only need a small amount (follow label directions), with the result being that you’ll need to water less often as plants grow.  This kind of addition is especially useful in hanging baskets that tend to dry out quickly, especially those lined with coir (coconut husk fiber), and in pots made of fiber or clay.

Check apple, cherry, and other fruit trees for nests of tent caterpillars. Blast low-lying nests with water to destroy them, or knock them to the ground and destroy them. A spray of BtK (make sure to get the “K” version) will kill emerging caterpillars but, being a natural bacterium, is not toxic to beneficial insects, birds, or humans.

Hummingbirds arrive back in our area usually in late April in southern locations, early May in the north.  After their incredibly long journey northward, they're ready for food.  Hang a hummingbird feeder or two this time of the year, and either use hummingbird food you can buy (a powder to mix with water), or make your own. 

To make your own food for “hummers”, add two cups of sugar to a quart of water, heat to dissolve, then allow to cool before placing out.  Don't use any other additives such as food coloring.  Refrigerate what you don't use, and replace the feeder food every few days.  If your feeder hangs from a pole, and ants find it, put Vaseline on a section of the pole to deter the ants.

Each year in the recent past, new annual flowers were displayed at the Burlington Waterfront Park and rated by Dr. Perry (pss.uvm.edu/ppp/aaswp.html), so you can find out which grow best in our North Country summers.  Some of the top flowers in recent years included Toucan Red canna, Bandana Pink lantana, and Bicolor Pink Stream alyssum.  Several petunias rated highly Supertunia Picasso in Purple, Vista Bubblegum and Vista Fuchsia.  There were several excellent foliage annuals grown for their colorful leaves.  Among these were Black Stockings fountain grass (this one can reach 7 feet high with roots that break pots), Sweet Caroline Bewitched Green with Envy sweet potato, Peter Wonder coleus, Royal Hawaiian Black Coral and Maui Gold elephant ears, and Quicksilver artemisia.

Among the many other gardening activities for this month are watching for ticks, pruning off lilac blooms when finished, and dividing perennials if they’re overgrown.

(Charlie Nardozzi is a nationally known horticulturist, author, gardening consultant, and garden coach; gardeningwithcharlie.com).   

Return to Perry's Perennial Pages: Green Mountain Gardener Articles-- your reliable source of gardening information for over 50 years.