Leonard Perry, UVM Horticulturist
and Charlie Nardozzi, Garden Consultant
Dividing ornamental grasses, supporting flower stems, and moving spring-flowering bulbs are some of the gardening activities for this month.
Support single stems, such as delphiniums, with stakes. I like
to use green plastic-coated metal ones, or iron rods (like used to
reinforce concrete), as these don't rot as wood does. Use soft
twine, foam cord, plastic plant tape or Velcro plant tape to tie
stems to stakes. These avoid cutting into and harming the soft
If using narrow stakes, such as bamboo or iron rods, place some
form of caps on top to avoid possible eye damage. One cap I use on
thick stakes is a wood filial (the kind placed on decking rails),
with hole drilled part way through the center. Less attractive is
a small piece of old garden hose. For bamboo stakes, pencil
erasers work well on tips.
If large clumps of Siberian iris or ornamental grasses, such as
maiden grass, have hollow centers, this is a sign they need
dividing for best growth. Large clumps can have massive roots and
be quite heavy, so we find it easier to just divide pieces off the
sides rather than to lift the whole clump. A square-tipped spade
works best for this. You may even need to get such divisions
started with a hatchet!
If you want or need to move some spring-blooming bulbs to another
spot, wait until the foliage has turned yellow, 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. Or, you can plant them now. Unless daffodils are
flowering less each year, they shouldn’t need dividing. Unless
tulips are labelled as “perennial”, they’ll only last one year and
so should be treated like annuals after bloom—dug up and
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 Bt will kill
emerging caterpillars but is not toxic to beneficial insects,
birds, or humans.
Grubs are short, squat white larvae that feed on roots of
lawngrasses and other plants, and eventually turn into beetles
that feed on leaves. While you’ll see recommendations and ads for
products to apply now for these, the best biological controls are
beneficial nematodes. These are best applied in late summer
during the young stages of new grubs.
Milky spore is another organism that attacks grubs, but only
those of the Japanese beetle. There are other types of grubs,
such as those of the rose chafer and Asiatic garden beetle, so
before using this product make sure you know which grubs are
present. Your state Extension diagnostic lab can identify grubs
(www.nepdn.org). Milky spore is often not recommended in New
England as it is less effective and spreads more slowly in cold
climates and soils, needs to be applied over a larger area than a
home landscape to be very effective, takes 2 to 4 years to work,
has variable results, and only will keep populations of grubs
lower and not eliminated.
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