The Homeowners Column

The Homeowners Column

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A Flurry of Activities for May Days in the Garden

Photo of Sandra Mason

Sandra Mason
State Master Gardener Coordinator

First I am compelled to apologize to all the honeys out there that will be the "gleeful" recipients of the following "honey do" list. Sorry but as in life, so goes the garden. Timing is everything and every hive has its worker bees.


Remove spent flowers on spring flowering bulbs such as tulips and daffodils, but wait until leaves turn yellow before removing. Make notes now of where additional spring bulbs can be planted in October.

Travel to Allerton Park in Monticello to enjoy the bodacious blooms in the peony garden. These new cultivars do not require staking or caging.

Finish planting annual flowers. Plant tropical water lilies when water temperature is over 55ยบ F.

Over-wintered tender annuals or tropicals such as hibiscus, gardenia, mandevilla, and geranium may be pruned, cleaned, fertilized, and moved outdoors in mid-May.

Begin pinching top 1-2 inches of new growth on chrysanthemums to encourage full bushy plants. Stop pinching in early July.

With clump-forming perennial flowers such as asters, beebalm, and tall phlox pinch out the top growth of the front half of the clump. This technique extends the bloom time as the front half blooms about 2 weeks later and also shapes the clump into attractive tiers.

Finish dividing and moving perennial plants. Wait until August to divide iris and September to divide peonies.

Experiment with removing a few inches of the top growth of tall sedum to keep it from flopping apart. If this is not successful, dividing plants may be needed.

Severely prune sage, butterfly bush, lavender, Russian sage, and Caryopteris to stimulate growth.


If not accomplished in April, fertilize in early May with one pound of actual nitrogen per 1,000 square feet. Slow release nitrogen forms are preferred.

Finish any seeding.


Pick strawberries and keep plants watered.

Mulch blueberries and keep watered as they form fruit.


Pinch azalea and rhododendron blossoms as they fade. Fertilize after bloom with fertilizer for acid-loving plants.

Prune spring flowering shrubs such as lilac, weigela, viburnum, and forsythia soon after bloom using renewal method by pruning oldest stems to the ground.

Monitor pines especially Scotch and mugho for caterpillar-like sawfly larvae on new shoots. Hand removal is effective or insecticide sprays of spinosad, neem oil or permethrin.

Scout for pine needle scale and oystershell scale crawlers by circling stems with inverted black tape. Young crawlers are usually present as bridal wreath spirea is in late bloom or has finished bloom, typically late May. Timing is crucial for scale control since sprays are most effective on the young crawlers. Insecticides to use include insecticidal soaps and summer oil sprays.

Early June scout for and spray euonymus scale when catalpa starts to bloom.


Mid-May plant sweet corn, squash, tomatoes, eggplant, sweet potato, and other warm loving crops. Allow recommended space between plants to lessen disease and crowding.

To allow root development, thin carrots, radishes and beets to 1-3 inches apart depending on size of variety.

Continue to harvest asparagus and rhubarb through May and into June. A full harvest season is 8-10 weeks starting in spring.

Plant transplants or seeds of annual herbs such as basil and dill. Sow extra dill or parsley for the swallowtail caterpillars.


Mulch with organic mulches such as wood chips to reduce weeding and conserve moisture.

Be sure to read, understand, and follow all pesticide label directions.

Set up rain barrels and compost bins.

City of Urbana, City of Champaign and University of Illinois Extension compost bin and rain barrel sale Saturday, May 16, 2015 from 9 a.m. to 3 p.m. in the parking lot on the corner of S. Vine St. and E. Green St. in Urbana. (north of the City building, across from Lincoln Square). Compost bins are $50 and rain barrels are $60. Rebates available for Champaign and Urbana residents.

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