University of Vermont
Department of Plant and Soil Science

Spring News Article
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SOWING SEEDS AND OTHER MAY GARDENING TIPS

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 frost. 
   
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 humans.
   
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; gardeningwithcharlie.com).

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