Monthly Gardening Calendar
Sharon Morrisey, Consumer Horticulture Agent
Milwaukee County UW-Extension

The excitement of spring mellows in June. Summer is here bringing some long awaited warmth.

The heat and sun make plants thirsty, especially if recently planted. Whenever possible, avoid overhead watering to reduce humidity and leaf wetness which encourage leafspot diseases. Direct water to the roots and use mulch to hold in moisture.

The numbers in parenthesis following an entry in this month's calendar can be used to get more detailed information. Dial 414-290-2450 for the UW-Extension's InfoSource system. Then follow the directions to use the three digit numbers given here to listen to a pre-recorded message on that topic. Also check the daily Dial-A-Garden-Tip, topic #791, for a timely gardening tip every day of the year.

Visit the UW-Extension’s Horticulture Team website at www.uwex.edu/ces/wihort. You'll find factsheets, articles and lots of links to other great gardening-related sites.
 

First Week

June 1st is considered to be relatively safe to transplant tomatoes to the garden. Plants with spindly stems can be buried in a trench up to their first set of true leaves. All other plants should be planted to the same depth as they were growing in the pot.

Don't fertilize tomatoes until the first fruit has set. Too much nitrogen will cause leafy growth at the expense of flowers and fruit. Most other plants benefit from a starter fertilizer when transplanted.

June 1st is also when your first lawn fertilizer application should be made. If you fertilized earlier this spring, wait until Labor Day or Halloween to do it again. However, if you routinely water your lawn all summer long, another light application may be needed in July.

It is too late for broadleaf weed control products or combination weed 'n feeds. Summer's heat will cause the weed killer to vaporize and drift, damaging other flowers & vegetables. Total vegetation killers such as glyphosate can be used all season but will kill everything so don’t use them in your lawn or allow overspray onto desirable plants.

Fertilize bulbs and most perennial flowers now for good growth all season.

Prune, transplant and up-pot houseplants since they will be growing most vigorously now due to the longer days, higher light, and warmer temperatures. Fertilize monthly.

Houseplants really benefit from a summer vacation in a shady spot in the yard. Even those that prefer very bright light should be in the shade. Surprisingly, outdoor shade is still brighter than almost any spot indoors. Plus the move back into the house in the fall will be less traumatic.

Prune out and destroy webs of Eastern tent caterpillar found wrapped around branches of fruit trees including crabapples. The biological control sold as Dipel, Bactur, or Thuricide is only effective while the caterpillars are still small. Soon they will move off the trees to pupate. Destroy these pale yellow, loosely constructed cocoons. In August look for shiny brown egg masses on tree branches. Prune them out or scrape them off.

Examine honeylocust and ash foliage for plant bugs. Control with insecticidal soap sprays as needed.
(HONEYLOCUST)     (ASH)

Preventative insect control for fruit bearing trees should have been started at petal fall. Continue every 10-14 days until autumn leaf drop.

Preventative treatment for apple scab and rust diseases should have been started before bloom started. For crabapples, collecting and destroying fallen leaves all season combined with proper watering and a fall fertilizer application may be all that is really necessary since these diseases are not life threatening.
(PEST CONTROL)     (SCAB DISEASE)

There are many insect pests to watch for in the vegetable garden now. The following are pests in Wisconsin:
(DISEASE)     (INSECTS)

The flea beetle chews many small holes in the leaves of a wide range of vegetable crops especially young transplants of the cole crops (broccoli, cauliflower, cabbage, and Brussels sprouts). Cover with floating row cover to exclude these tiny, hopping bugs before they begin feeding. This covering can be left in place day and night since it is permeable to light and moisture. It also "breaths" so that heat does not build-up underneath. Be sure to seal the lower edges with soil or stones. Allow ample room underneath for plant growth.

Covering cole crop plants with floating row cover will also exclude egg laying by the cabbage moths.

Potato leafhoppers are wedge-shaped, bright green insects that cause "hopperburn" on plant leaves beginning in early June. Spray once with carbaryl or malathion and cover the entire crop with row cover to prevent invasion.

Colorado potato beetle adults and larvae can be hand picked to remove or sprayed with M-Trak, a biological control product. Adults are yellow and black striped beetles and the larvae are humpbacked and red. Look for them on the stem tips. They are present almost all season.

Striped and spotted cucumber beetles transmit a bacterial wilt to cucumbers, squashes, and melons. Adults and eggs can be hand picked throughout the season or preventative sprays or dusts with rotenone or carbaryl can be applied regularly. Leaves of infected plants wilt only during the day but the leaf stems remain erect. Eventually, the entire plant wilts and dies.

Watch for another invasion this year of Mexican bean beetle. Last year’s assault caught us by surprise. Cover the entire crop with floating row cover as soon as plants emerge. Spray with carbaryl at the first sign of beetles or feeding damage.

Second Week

Fertilize and renew June bearing strawberries after harvesting. Use 6 lbs. of 10-10-10 per 100 ft. of row. Plants form runners now and need good fertility for vigorous growth.  Renovate by mowing the foliage and cultivating between the rows.
 

Aphids of all types show up on a range of host plants as soon as the warm weather arrives. Look for them in newly unfurling foliage, which may be curled downward and around aphid colonies. Sticky leaves are also a sign of their presence since they secrete "honeydew". Black sooty mold may also grow in this sticky substance but it does little damage since it does not penetrate the leaves. Aphids, however, do damage the plant. Spray leaves with a strong jet of water to dislodge some of them. Insecticidal soap is a low-toxicity product that provides pretty good control as long as the insects are wetted thoroughly. A second and third treatment to kill newly hatched eggs may be needed in 5 - 7 days.

Check spruce and arborvitae growing in hot, dry sites for spider mites. Tap a branch several times on a piece of white paper and then hold it very still for about 30 seconds. Mites will appear as tiny, moving black specks. If present, thoroughly wet plants with a blast of water from the hose. Repeat until no mites are found.

Continue mowing around ripening foliage of spring flowering bulb plants growing in the lawn. For best flower bud development and vigorous growth next year, allow leaves to yellow completely before removing.

Third Week

Once the soil has warmed, put a 2 – 4” layer of organic mulch on flowerbeds and around trees and shrubs. Good mulches include shredded bark, woodchips and chipped yard waste often available from your municipality. Mulch discourages weed growth, holds in soil moisture and maintains even soil temperatures. Around trees, it may simply serve to help prevent “mower damage” to trunks. Better yet expand the mulch ring to include the entire rootzone or at least out to the “drip line”. Spruces and birches really benefit from this to reduce drought stress and resulting disease and insect problems.

Squash vine borer adults are 1" long orange and green day flying moths that are emerging from the soil now. They lay brown, button-shaped, 1/16" eggs at the base of the vines of summer and winter squashes. Examine stems daily and remove eggs by hand to prevent burrowing of larvae as they hatch. Wrap lower 6 - 12" of stem with aluminum foil or floating row cover to prevent egg laying. Stem bases can be sprayed with carbaryl weekly for three weeks. The liquid seems to be more effective than dust.

Red sphere traps coated with Tanglefoot can be hung in apple trees now to control apple maggots. Use 1 trap per 100 apples expected.

Fourth Week

Newly established plantings of raspberries can be fertilized now with 2 -3 lbs. of ammonium nitrate.

Fertilize roses after the first flush of blooms. Use one tablespoon of a complete, low nitrogen fertilizer per plant.

Pinch back chrysanthemums one last time now to promote fuller, denser growth. Flower buds will form on new growth for fall display.

Oak, elm, and maples with one of the wilt diseases will begin to show typical wilting symptoms as the summer heats up. Watch particularly the upper crown for branches with wilted leaves. Call your county UW-Extension to assist with diagnosis at the first signs of wilt.
(OAK)     (ELM)     (MAPLE)