Garden Clippings 2016 Vol. 36:2

April is the Month to...

• Prune summer and fall flowering shrubs. Early April is good a good time to prune summer flowering shrubs such big leaf hydrangea, panicle hydrangea, butterfly bush, buttonbush, summersweet clethra, sweetspire, and summer flowering spirea, since these shrubs form their flower buds on the current season’s stem growth. Pruning these in winter or early spring leads to vigorous stem growth in spring and summer that contains buds that will flower in summer and early fall.
• Start seeds of warm season plants indoors. Seeds of warm season plants such as tomatoes, cucumbers, eggplants, peppers, marigolds and zinnias can be started indoors in April for transplanting later to the garden when it gets warmer. Starting your vegetable seeds early will give your garden a jumpstart on spring by having plants ready when you want to transplant. When selecting vegetable varieties, check for the number of days needed to harvest. Varieties with a smaller number of days until harvest will mature sooner. Make sure to follow seed packet or catalog instructions, as each species has its own requirements. Provide up to 16 hours of light per day by using cool white fluorescent light fixtures or grow lights suspended 6-12 inches above the plants. Make sure to move the lights up as plants grow. If you don’t have enough artificial light, place plants in a south facing window, making sure to rotate the containers to get sturdy, uniform straight plants. Providing bottom heat speeds up germination and produces healthier roots and plants, and can prevent “damping off” disease that causes death of tiny seedlings. Electric heating mats specifically for seed starting are available from many garden centers.
• Sow seeds of cool season crops in the field. Seeds of leafy greens such as lettuce, chard, kale, or arugula and roots crops such as carrot, radish, beet and turnips can be planted in the field in April. Plant the seeds as soon as the ground can be worked. You can also set out transplants. Transplants are preferred for leafy vegetables such as kale and chard, as they establish faster and mature early. Cool season crops such as spinach, beets, radish, carrots and lettuce are sowed thickly in rows and thinned later to allow each plant sufficient space. Root crops such as carrots, beets, and radishes should be thinned to 2-inch spacing to allow the roots to develop properly. They can be thinned as soon as they reach small edible size.
• Rake the lawn to remove dead grass and other debris. To facilitate quicker regrowth, rake the turf lightly with a leaf rake. Do not use a garden rake as it may damage the turf. Raking will remove dead and blighted blades and other debris, facilitate recovery from snow mold, and promote quicker regrowth.
• Divide perennials. Many perennials tend to die out from the center if not divided on a regular basis. The frequency of dividing perennials depends on the species. Most perennials respond best when divided in early spring when the weather is cool and there is usually adequate moisture in the soil. Roots have a lot of stored energy that will help the divisions recover from being cut apart and replanted. The new emerging shoots are likely to suffer less damage than fully developed growth and will also lose less water through evapotranspiration. Spring divisions also have the entire season to recover from the stress of division. Start by digging around the plant, then lift the entire clump out of the ground. Using a spade or sharp knife, cut the clump into several smaller pieces. Discard the old, dead center and trim off any damaged roots. Keep the divisions moist and shaded while you prepare the new planting site. After replanting, keep them watered well.
• Prepare garden soil for planting. Do not work your soil when it is wet. Tilling or digging when the soil is wet will cause it to dry into hard clods. To test if your soil is dry enough to be worked, take a handful of soil and squeeze it. If the soil crumbles easily when you open your hand, it is ready to be tilled. If it does not crumble or water seeps out, it is too wet. Allow the soil to dry for a few more days and test again before digging.
• Make lawn repairs. If you have areas of your lawn that were damaged during the winter, April is a good time to repairs those areas. It is important to do a soil test before applying any fertilizer so that you apply according to rates recommended by the soil test. Keep the seeded area moist throughout establishment. Water lightly several times a day and avoid runoff. A mulch cover will help keep the area moist and reduce watering frequency. Avoid applying herbicides during the establishment period (spring), as this may cause injury to the new plants.
• Plant cold tolerant flowers. Pansies and other cold tolerant flowers such as petunia and snapdragon can be planted in April. As these plants become available at local garden centers, prepare your gardens for planting. Place these plants where they will receive full sun, though some pansies may tolerate partial shade. Water plants thoroughly after planting and mulch lightly with organic mulch if possible.
• Plant a tree to celebrate Arbor Day on April 29. Arbor Day is an annual observance that celebrates the role of trees in our lives and promotes tree planting and care.

Author: Geoffey Njue, Green Industry Specialist