May Gardening Calendar

by Cathy Bylinowski, Horticulture Instructor, University of Missouri Extension—Jackson County
 

     It has been a wild spring so far with temperatures all over the place, from freezing to hot.  Snow, rain, wind, we have experienced it all. Despite these extremes, I hope you are able to get outside and start gardening during the stay at home precautions and enjoy the spring activities in your yard and garden.
     Contact University of Missouri Extension in Jackson County, if you have any questions about plants, insects, or any garden related activities. We are glad to help! Cathy Bylinowski, Horticulture Instructor, [email protected], University of Missouri Extension- Jackson County, 816-252-5051.
 
Ornamentals
Apples, crabapples and hawthorns susceptible to rust disease should have protective fungicidal sprays applied beginning when these trees bloom.
Pinch azaleas and rhododendron blossoms as they fade. Double flowered azaleas need no pinching.
If spring rains have been sparse, begin irrigating, especially plants growing in full sun.
Fertilize azaleas after bloom. Use a formulation which has an acid reaction.
Canker worms (inch worms) rarely cause permanent damage to ornamentals. Use Bt if control is deemed necessary.
Don't remove spring bulb foliage prematurely or next year's flower production will decline.
Continue monitoring pines, especially Scotch and mugo, for sawfly activity on new shoots.
Begin planting gladiolus bulbs as the ground warms. Continue at 2-week intervals.
Plant hardy water lilies in tubs or garden pools.
Scale crawlers are active now. Infested pines and euonymus should be treated at this time.
Plant summer bulbs such as caladiums, dahlias, cannas and elephant ears.
Begin planting warm-season annuals.
Begin fertilizing annuals. Continue at regular intervals.
Trees with a history of borer problems should receive their first spray now. Repeat twice at 3-week intervals.
Pinch back mums to promote bushy growth.
 
Lawns
Keep bluegrass cut at 1.5 to 2.5 inch height. Mow tall fescue at 2 to 4 inch height.
Mow zoysia lawns at 1.5 inch height. Remove no more than one-half inch at each mowing.
Apply post-emergence broadleaf weed controls now if needed.
Zoysia lawns may be fertilized now. Apply no more than 1 pound of actual nitrogen per 1000 square feet.
Watch for sod webworms emerging now.
 
Vegetables
Place cutworm collars around young transplants. Collars are easily made from cardboard strips.
Growing lettuce under screening materials will slow bolting and extend harvests into hot weather.
Slugs will hide during the daytime beneath a board placed over damp ground. Check each morning and destroy any slugs that have gathered on the underside of the board.
Plant dill to use when making pickles.
Keep asparagus harvested for continued spear production. Control asparagus beetles as needed.
Begin planting sweet corn as soon as white oak leaves are as big as squirrel ears.
Isolate sweet, super sweet and popcorn varieties of corn to prevent crossing.
Thin plantings of carrots and beets to avoid overcrowding.
Control caterpillars on broccoli and cabbage plants by handpicking or use biological sprays such as B.t.
Set out tomato plants as soils warm.
Place a stake by seeds of squash and cucumbers when planting in hills to locate the root zone watering site after the vines have run.
Remove rhubarb seed stalks as they appear.
Watch for striped and spotted cucumber beetles now. Both may spread wilt and mosaic diseases to squash and cucumber plants.
Set out peppers and eggplants after soils have warmed. Plant sweet potatoes now and into early June.
Make new sowings of warm-season vegetables after harvesting early crops.
 
Fruits
Mulch blueberries with pine needles or sawdust.
Don't spray any fruits while in bloom. Refer to local MU Extension publications for fruit spray schedule. Fruit Tree Spray Schedule for the Homeowner- https://extension2.missouri.edu/g6010
 
Miscellaneous
Birds eat many insect pests. Attract them to your garden by providing good nesting habitats.
Herbs planted in average soils need no extra fertilizer. Too much may reduce flavor and pungency at harvest.
Take houseplants outdoors when nights will remain above 50 degrees. Most prefer only direct morning sun.
Watch for fireflies on warm nights. Both adults and larvae are important predators. Collecting may reduce this benefit.
Gardening Calendar supplied by the staff of the William T. Kemper Center for Home Gardening located at the Missouri Botanical Garden in St. Louis, Missouri. (www.GardeningHelp.org)