University of Vermont
Department of Plant and Soil Science
SOWING SEEDS AND OTHER MAY GARDENING
Leonard Perry, UVM Horticulturist
and Charlie Nardozzi, Garden Consultant
Sowing or planting vegetables, moving bulbs properly and at the right time,
and making large container plantings easier to move are some of the
gardening activities for this month.
Sow “cool” crops such as carrots, lettuce and peas directly in the garden
early in the month. Sow “warm” crops such as beans, corn, melons, and
squash at the end of the month when soils have warmed and after the last
To get a jump on our relatively short growing season, you can start some
warm-season crops indoors. Other warm-season crops like tomatoes and
peppers need longer to grow before setting out so, if you didn’t start them
in April, it’s best to buy transplants. But don’t get too eager to
plant out or sow warm-season crops! If air and soils haven’t warmed
sufficiently (65 degrees soil or above is best), wait to plant.
Since melons, squash, and cucumbers don’t like transplanting, sow directly
in peat pots or similar degradable containers that can be planted directly
in the ground. When doing so, make sure the tops of such pots are
broken off or buried, so they don’t wick water from the root zone.
If you want to move some spring-blooming bulbs to another spot, 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 need
to move the bulbs sooner, dig and "heel" in (temporarily plant) out of the
way, marking where they are so you can find them once the foliage has died.
Use clay or metal "plant feet" underneath large containers to help with
drainage and to keep pots from staining wood decks and steps. For heavy
indoor plants that you summer outdoors, use plant trivets with four casters
to make moving them in and out less backbreaking.
When planting large containers for the deck or patio, save on soil by
creating a false bottom. Recycle foam packing peanuts by using these
in the very bottom, or use bark or wood chips, then cover with landscape
fabric or a piece of cardboard to keep the soil from sifting around them. Or
you can use plastic pots, upside down, instead. Most of the plants
you'll use don't need more than about a foot of soil depth for their roots.
Check apple, cherry, and other fruit trees for nests of tent caterpillars.
They will emerge at the same time the leaves sprout. Blast nests with
a strong spray of water to destroy them, or use a pump sprayer with “Bt”
insecticide. Make sure to follow label directions, even though Bt will
harm only the caterpillars and not other beneficial insects, birds, or
Cut back dead canes of roses to healthy tissue, and remove any spindly
branches. Make a slanted cut that angles up toward an outward-facing bud,
starting one quarter inch above the bud. This directs the new canes to grow
outward, which improves air circulation in the middle of the plant and so
reduces the risk of diseases like black spot.
Other activities for this month include putting out hummingbird feeders
early in the month, acclimating seedlings from indoors to outdoors
gradually, protecting bees by not using insecticides on plants in bloom,
staking plants that will get tall, digging and dividing perennials if needed
(overgrown, hollow centers of plants, few blooms last year), and keeping up
with mowing but not mowing too low—3 to 4-inches high is good.
(Charlie Nardozzi is a nationally
known horticulturist, author, gardening consultant, and garden coach;
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