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Your gardening tasks for May


Category
Week
Activity
 
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2
3
4
 
Ornamentals x x x x Apples, crabapples and hawthorns susceptible to rust disease should have protective fungicidal sprays applied beginning when these trees bloom.
  x x x x Pinch azaleas and rhododendron blossoms as they fade. Double flowered azaleas need no pinching.
  x x x x If spring rains have been sparse, begin irrigating, especially plants growing in full sun.
  x x x x Fertilize azaleas after bloom. Use a formulation which has an acid reaction.
  x x o o Canker worms (inch worms) rarely cause permanent damage to ornamentals. Use B.T. if control is deemed necessary.
  x x o o Don't remove spring bulb foliage prematurely or next year's flower production will decline.
  x o o o Continue monitoring pines, especially scotch and mugo, for sawfly activity on new shoots.
  x o o o Begin planting gladiolus bulbs as the ground warms. Continue at 2 week intervals.
  x o o o Plant hardy water lilies in tubs or garden pools.
  o x x x Scale crawlers are active now. Infested pines and euonymus should be treated at this time.
  o x x o Plant summer bulbs such as caladiums, dahlias, cannas, elephant ears.
  o x o o Begin planting warm-season annuals.
  o o x x Begin fertilizing annuals. Continue at regular intervals.
  o o x x Trees with a history of borer problems should receive their first spray now. Repeat twice at 3 week intervals.
  o o x x If spring rains have been sparse, begin irrigating, especially plants growing in full sun.
  o o x x Bulbs can be moved or divided as the foliage dies.
  o o o x Pinch back mums to promote bushy growth.
Lawns x x x x Keep bluegrass cut at 1.5 to 2.5 inch height. Mow tall fescue at 2 to 3.5 inch height.
  o x x x Mow zoysia lawns at 1.5 inch height. Remove no more than one-half inch at each mowing.
  o x x x Apply post-emergence broadleaf weed controls now if needed.
  o o x x Zoysia lawns may be fertilized now. Apply no more than 1 pound of actual nitrogen per 1000 square feet.
  o o o x Watch for sod webworms emerging now.
Turfgrass x x x x Keep bluegrass cut at 1.5 to 2.5 inches in height.
  x x x x Mow tall fescues at 2 to 3.5 inch height.
  o x x x Mow zoysia lawns at 1.5 inch height. Remove no more than one-half inch at each mowing.
  o x x x Apply post-emergence broadleaf weed controls now if needed.
  o o x x Zoysia lawns may be fertilized now. Apply no more than 1 pound of actual nitrogen per 1000 square feet.
  o o o x Watch for sod webworms emerging now.
Vegetables x x x x Place cutworm collars around young transplants. Collars are easily made from cardboard strips.
  x x x x Growing lettuce under screening materials will slow bolting and extend harvests into hot weather.
  x x x x 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.
  x x o o Plant dill to use when making pickles.
  x o o o Keep asparagus harvested for continued spear production. Control asparagus beetles as needed.
  x o o o Begin planting sweet corn as soon as white oak leaves are as big as squirrel ears.
  x o o o Isolate sweet, super sweet and popcorn varieties of corn to prevent crossing.
  x o o o Thin plantings of carrots and beets to avoid overcrowding.
  x o o o Control caterpillars on broccoli and cabbage plants by handpicking or use biological sprays such as B.T.
  x o o o Set out tomato plants as soils warm. Place support stakes alongside at planting time.
  o x x o 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.
  o x x o Remove rhubarb seeds stalks as they appear.
  o x o o Watch for striped and spotted cucumber beetles now. Both may spread wilt and mosaic diseases to squash and cucumber plants.
  o o x x Set out peppers and eggplants after soils have warmed. Plant sweet potatoes now.
  o o o x Make new sowings of warm-season vegetables after harvesting early crops.
Fruits x x x x Mulch blueberries with pine needles or sawdust.
  x o o o Don't spray any fruits while in bloom. Refer to local Extension publications for fruit spray schedule.
  o o o x Prune unwanted shoots as they appear on fruit trees.
Miscellaneous x x x x Birds eat many insect pests. Attract them to your garden by providing good nesting habitats.
  o x x x Herbs planted in average soils need no extra fertilizer. Too much may reduce flavor and pungency at harvest.
  o o x x Take houseplants outdoors when nights will remain above 50 degrees. Most prefer only direct morning sun.
  o o x x Watch for fireflies on warm nights. Both adults and larvae are important predators. Collecting may reduce this benefit.
  o o x x Sink houseplants up to their rims in soil or mulch to conserve moisture. Fertilize regularly.

Missouri Botanical Garden, 2001-2011