Pinch azaleas and rhododendron blossoms as they fade. Fertilize them after they bloom using an azalea or blueberry fertilizer. Soil acidity must be maintained for good growth. For more information, see MU Extension Guide g6825 Growing Azaleas and Rhododendrons https://extension.missouri.edu/g6825.
Do not remove foliage from spring bulbs too soon or it will lead to no flowering next spring.
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.
If you love to garden, but do not have a lot of time, choose plants that are easy to maintain. Plants that do not need "deadheading" include begonia, impatiens, alyssum, ageratum, lobelia, vinca and salvia.
Prune blooming shrubs right after flowers have faded if needed.
Some common ground covers suitable for sunny locations include Ajuga, creeping phlox, and creeping juniper. Be aware the groundcovers can be invasive. For more information, see MU Extension Guide g6835 Selected Ground Covers for Missouri https://extension.missouri.edu/publications/g6835.
Begin planting gladiolus, caladiums, dahlias, cannas, and elephant ears.
Plant hardy water lilies in tubs or garden pools.
Start inspecting your plants for scale crawlers and other insects. For more information, see MU Extension Guide 7274 Aphids, Scales and Mites on Home Garden and Landscape Plants https://extension.missouri.edu/g7274.
Do not remove spring bulb foliage prematurely or next year's flower production will decline. Foliage should be left to feed the bulb. Bulbs can be moved or divided as foliage dies. Bulbs can also be marked for fall transplanting and division.
Growing lettuce under screening materials will slow bolting and extend harvests into hot weather.
Place cutworm collars around the base of the stems of young transplants. Collars are easily made from cardboard strips.
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.
Place a stake or flag by seeds of squash and cucumbers when planting in hills to locate the root zone watering site after the vines have run.
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, follow the directions on the label.
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.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.
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.
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 N/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.
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 particularly prevalent in wet springs.