May Gardening Tips

by Cathy Bylinowski, M.S., Horticulture Instructor, University of Missouri Extension
 

     May is a great time to start a vegetable or ornamental garden, to plant shrubs and trees, and to take care of the lawn. Here are some tips to help you get started on a wide range of gardening activities:
 
Outdoor ornamentals:
     Pinch back mums to promote compact, bushy growth.
    Lightly side-dress perennials, including spring bulbs, with a 5-10-10 or 10-10-10 fertilizer, being careful to avoid the center or crown of the plant.
    Some common ground covers suitable for sunny locations include Ajuga, creeping phlox, and creeping juniper.
     Do not remove spring bulb foliage prematurely or next year's flower production will decline. Foliage should be left to feed the bulb via photosynthesis. Bulbs can be moved or divided as foliage dies. Bulbs can also be marked for fall transplanting and division.
     Prune blooming shrubs right after flowers have faded if needed.
Check for newly hatched bagworms on evergreens and conifers. For more information, see MU Extension Guide g7250 The Bagworm in Missouri https://extension.missouri.edu/g7250.
 
Vegetable Gardening:
     Plant tomatoes in warm soils.   
Mulch around plants and use support stakes or cages at planting time.
     Control caterpillars on broccoli and cabbage plants by handpicking or use biological sprays such as B.T. (bacillus thuringiensis) or Spinosad.
     Watch for striped and spotted cucumber beetles now. Both may spread wilt and mosaic diseases to squash and cucumber plants.
     Remove rhubarb seed stalks as they appear.
     Plant peppers and eggplants after soils have warmed.
     Plant sweet potato slips now.
     Begin planting sweet corn at two-week intervals. For good pollination, plant in block formation with a minimum of 4 rows. Isolate sweet, supersweet and popcorn varieties to prevent cross pollination by separating varieties by 250 feet apart or a difference of 14 days.
     Plant multiple plantings of cilantro or keep bloom heads cut off. It tends to go to seed quickly.
Herbs planted in average soils need no extra fertilizer. Too much may reduce flavor and quality at harvest.
     Scout for insect and disease problems in the garden. If you use a pesticide, please follow the directions on the label.
 
Fruit Trees and Berries:
     Follow fruit tree spray guide by the University of Missouri Extension. For more information, see MU Extension Guide g6010 Fruit Spray Schedule https://extension.missouri.edu/g6010.
     Don't spray insecticides while fruit trees are in bloom. Protect pollinators. Fungicides, however, can still be sprayed.
     Keep on top of weeds in the strawberry patch. They can quickly get out of hand. Weeds are detrimental to strawberry plants.
     Begin training new shoots on fruit trees. Prune unwanted shoots as they appear.
     Mulch blueberries with pine needles or aged sawdust.
     Continue thinning peaches and apples to promote large fruit size and prevent limb breakage.
 
 
 
Lawns:
 
Tall Fescue and Kentucky Bluegrass
    Mow lawns at 3.5–4 inches, frequently (once a week) if lawn is quickly growing. Do not mow too short!
     Restrict nitrogen applications to 0.5 lb. Nitrogen per month or less, particularly quickly available soluble forms.
     Apply postemergence broadleaf herbicides for summer weeds. If needed, start postemergence control of crabgrass, goosegrass or nutsedge near the end of the month.
     Watch for first brood of sod webworm which is rare. Apply curative insecticides only if needed.
 
Zoysiagrass
    Wait for lawn to completely green up prior to mowing at a height of 1.5–2 inches.
     Later in the month, monitor for large patch disease which is prevalent in wet springs.
 
 
Mulching and Weed Control:
     Four to five layers of newspaper will serve as an effective mulch in the garden. Water the newspaper as it is applied and cover it with sawdust or straw to weigh it down, to reduce the white glare and prevent it from blowing away.
     If weeds get out of control this summer, consider smothering them out with black plastic or heavy cardboard weighted down to keep the wind from blowing it away.
     Have fun gardening this month! Enjoy the cool and sunny weather. Get ready for summer!
     Visit the main MU Extension website to find more horticulture information- https://extension.missouri.edu/
     To subscribe to the free online monthly newsletter Missouri Environment and Gardens and other MU Extension garden related publications, visit this website- https://ipm.missouri.edu/subscribe/