By Dr. Leonard Perry, Extension Professor
University of Vermont
Now that the weather is becoming spring-like, many home gardeners are getting the urge to work the soil. Although cool weather crops can be planted in most parts of Vermont this month, most of our gardening activity in April centers on preparation for the growing season.
First there's the soil test, which can help you plan a fertilizer program to keep your plants well fed. Test results include recommendations on how much lime your soil needs as well as the quantity and type of fertilizers to apply.
The University of Vermont (UVM) soil test provides specific recommendations for vegetables, flowers, turf, small fruits, or trees. The cost is $10, payable when you send the sample in, with kits available from all UVM Extension offices and many garden centers.
Additional tests are available for organic matter ($2), minor nutrients ($5) such as boron, or heavy metal contamination ($5). Greenhouse soils should be tested for salt content or conductivity ($3).
April is the time to start many annual flower and vegetable seedlings. As a rule of thumb, sow your seeds indoors about six to ten weeks before you plan to transplant them outdoors. Higher temperatures will speed germination and growth over cooler growing areas, so adjust dates accordingly by consulting the seed packet instructions.
A soil-less potting mix is best for germinating seeds. These are made from peat and vermiculite or perlite and usually contain enough fertilizer for the first month of plant growth. Using garden soil enhances the likelihood of damping-off diseases that attack seedlings.
Before planting seeds, moisten soil mix, but don't get it too wet. Sprinkle on more water after planting, as with a clothes sprinkler for ironing. To avoid leggy plants, supplement natural light available through windows by hanging one or two fluorescent shop light fixtures about six inches above the seedlings.
As the plants grow, raise the fixtures. A mix of cool white and warm white bulbs will provide the right quality of light for plant growth. Or use grow lights.
Outdoors, remove mulches from perennials, strawberries, and roses before they start to grow. Take care when removing mulches to avoid injury to plants. Keep an eye on the weather, too, as you may need to re-cover plants with mulches or plastic if a late frost is predicted.
This is also a good time to divide summer and fall flowering perennials if they are crowding out other plants. Peonies usually can be left for several years; more vigorously growing plants like yarrow may need division every year. Plants can be divided as soon as you see signs of growth.
Gently lift up the plant, dividing the roots to leave three to five growing points or eyes on each piece. For Siberian irises and daylilies you may need to use a knife or hatchet to divide clumps.
Replant about a foot apart. This will vary for different species. Consult your favorite gardening book for specific instructions.
There's still time to prune outdoor plants, but don't get carried away and cut off too much growth or prune spring-flowering plants such as lilacs and forsythia. The latter need to be pruned later this year, after they finish blooming. Prune evergreens just after they begin growth.
Other activities for April: celebrate the arrival of spring by buying a bouquet of daffodils or tulips; build a cold frame for hardening off tender transplants; service your lawn mower; sharpen and oil your gardening tools.
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