University of Vermont Extension 
Department of Plant and Soil Science
 

Spring News Article
 
APPLYING DORMANT SPRAYS AND OTHER APRIL GARDENING TIPS
 

By Dr. Leonard Perry, Extension Professor

Dr. Vern Grubinger, Extension Associate Professor
University of Vermont
 

In April, we can almost do everything outdoors again. For gardeners anxious to get back in the garden, that's good news. Although it's still a little too early to plant most vegetable crops, some seeds can be sown outdoors this month, with many others started indoors for transplanting when the weather warms up.

There are many early season tasks to do, including applying dormant sprays to fruit trees, ornamental shrubs, blueberries, and raspberries, to prevent damage from pests later in the season. Dormant sprays need to be applied to stems or canes before any new, green growth appears in order to avoid damage to plants. Dormant oil or superior oil helps control scales, mites, and other overwintering insects. Use lime-sulfur for suppression of fungal diseases, such as rust on roses or cane blights on blueberries and raspberries.

Apply dormant sprays as buds begin to swell but before any leaves emerge. Do not use if very warm or freezing temperatures are expected soon. Follow label directions carefully.

Outdoors, remove mulches from perennials, strawberries, and bulbs. Leaving them covered too long will result in poor growth that is more vulnerable to late freezes. Removing mulch shortly after new growth has started promotes hardiness and helps the soil and foliage to dry out, avoiding diseases that thrive in wet conditions. Keep plastic sheeting or mulch handy to re-cover plants for frost protection if a late freeze is predicted.

Remove dead foliage or stems from perennials if you didn't do so last fall. Wait until new buds form on roses before pruning. Stems that appear dead now may actually be alive and will start to grow next month.

April is the month to start your own plants indoors. In the first part of the month, you can start marigolds, tomatoes, broccoli, cabbage, and most other flower and vegetable seeds. Check the back of the seed packet to determine when transplants should be started. Keep in mind that most plants will germinate and grow slowly indoors if the temperature is cool. Warm conditions--70 to 75 degrees F--are optimal for starting most crops. High light conditions are necessary to prevent leggy growth. Since many varieties do well when sown directly in the garden, don't use up valuable indoor growing space starting quick growing varieties.

In late April, in many parts of Vermont, you can sow cool season crops like beets, carrots, lettuce, parsley, parsnips, onions, spinach, and peas outdoors in the garden, as long as the soil is dry enough to be worked. The best way to test this is to take a handful of soil and squeeze. If it balls up, it's too wet to till. If the soil crumbles, then it's okay to plant.

Till or hand spade the soil once, turning over any cover crops or plant residues. Add lime, fertilizer, and manure according to your soil test results. Make sure the manure is weed-free.

Work these amendments into the soil well to promote large healthy root systems and avoid harming the tender roots of plants as they begin to grow. If you have wood ashes from the wood stove, do not add them to the garden unless the soil is acid and in need of potassium. Even then, they must be used sparingly to avoid causing plant injury.

Did you get a lily for Easter? Easter lily blooms last longest if given bright, indirect light and cool temperatures (40 to 50 degree F nights, days below 70 degrees F). The soil also needs to be kept consistently moist.

If you want to save the bulb for planting outdoors, once the flowers have faded, continue to water regularly and feed with a regular houseplant fertilizer. The leaves will eventually yellow and die back to soil level. Plant the bulb outdoors once all danger of frost has past.

Cut the stem at the soil line, and plant in a well-drained location. Be sure to mark where you have planted the bulb so you don't dig up that area to plant something else. Fertilize twice during the summer. Mulch in late fall. If all goes well, expect the plant to bloom again next summer, and for many summers thereafter. Other Easter plants from bulbs like tulips, daffodils, and hyacinths also may be replanted outdoors following the same planting strategies.
 

As the days grow longer, houseplants will begin to show signs of new growth. They will benefit from more water and an application of fertilizer. Check for signs of insects. Plants that have outgrown their pots will need to be repotted. Make sure the new container has adequate drainage to prevent waterlogged soil and root rot.

Other activities for April: turn the compost pile; rake your lawn to remove dead grass and winter debris; remember your secretary on Professional Secretaries' Day, April 26.



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