University of Vermont Extension 
Department of Plant and Soil Science

Spring News Article


By Dr. Leonard Perry, Extension Professor

Dr. Vern Grubinger, Extension Associate Professor
University of Vermont

Despite the surprises Mother Nature may send our way in spring--such as unseasonable temperatures in March and heavy snows in April--by May her moods are calmer. For gardeners, this means there's almost no limit to the gardening activities that can be done this month.

First, finish up any chores that didn't get done in April, such as removing burlap wraps from trees and shrubs. Rake out flowerbeds and remove last year's stalks from perennial plants. If you can't break them off easily, cut them with a pair of sharp shears. Be careful not to remove new growth from plant crowns.

Prune broken branches from trees and shrubs before they fall and injure someone or damage the bark or other limbs. You also can prune summer flowering shrubs, hedges, and evergreen trees now. But by May it's too late to prune fruit-bearing trees like crabapple, plum, and cherry and too early to cut back spring-flowering varieties such as forsythia and lilacs. For the latter, wait until flowering is through for the year.

May is a good month to work on your lawn. Rake to remove dead grass. Top dress bare areas with a mix of topsoil and peat, then reseed. Use a quality grass seed mix containing Kentucky bluegrass, red fescue, and perennial ryegrass. Avoid zoysia and other warm-climate grasses as they will not do well in Vermont. Water seeded areas, keeping them moist as the grass starts to grow.

This is also a good time to fertilize your lawn to encourage healthy growth. Without a soil test, use a balanced fertilizer--one containing nitrogen, phosphorus, and potash. However, a soil test is recommended as it will tell you if your soil already contains enough potash and phosphate, in which case you may only need a light application of nitrogen. Many lawns also need lime to grow well. A soil test will tell you how much to apply.

This is, of course, the primary planting month for vegetable gardens. Early this month you can plant cool season crops such as peas, spinach, herbs, onions, and lettuce. Plant root crops, cole crops, and beans next. Wait until Memorial Day or later, depending on the last frost in your area, to put in tender crops such as tomatoes, peppers, eggplant, and melons.

If a late frost is predicted, be prepared to cover plants with plastic sheeting, straw, or individual containers to protect them from injury.

To avoid causing compaction, the soil must be dry enough to work before you plant. Take a handful of soil and squeeze. If it stays balled up, then the soil is still too wet. Just like with your lawn, a soil test will let you know what nutrients need to be worked into the garden. A healthy dose of well-rotted manure or compost is always a good source of slow-release nutrients. Remember that most vegetables prefer a soil pH, or acid level, of 6 to 7. Proper liming is key to "unlocking" nutrients in the soil. Lime also provides the calcium that plants need.

You can obtain a soil testing kit from any University of Vermont Extension office, many garden centers, or the Agricultural and Environmental Testing laboratory, Hills Building, on the UVM campus in Burlington. The cost is $10, payable when you submit the sample. You can request information on organic fertilizers in addition to the chemical fertilizer recommendations provided.

If you are thinking of putting in a new flowerbed, prepare the bed by working the soil to a depth of one foot. Mix in lime if needed (soil pH should be 6 to 7) and organic matter in the form of peat moss or compost. Pay attention to flower color and placement. If a bed is to be viewed from one side only, then place taller plants in the back. Otherwise, put them in the center of the bed.

Avoid planting all the early flowering plants in one area, or all varieties with the same flower type, such as spikes, together. If you are creating beds to be enjoyed from inside the house, plant hot-colored annuals and perennials (yellows, oranges, reds) in the front part of the bed. Plant blues and purples farther away. Adding plants with silvery foliage will help tie the color groups together.

When buying bedding annuals, select properly grown plants with good color. Plants should be vigorous and have well-developed root systems. Look for plants with lots of unopened buds.

You will need to harden off these plants before planting. This means acclimating them to the reduced humidity and cooler temperatures of the outdoors. To do this, place plants outside during the day, but bring indoors at night to protect from cool nighttime temperatures that may injure or kill plants. Gradually leave out for longer periods until fully acclimated. Tomatoes, peppers, and other transplants for the vegetable garden also require a period of hardening off.

Other activities for May: transplant roses and evergreen shrubs; start a compost pile for next year's garden; plant a hummingbird garden.

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