Gardening in Illinois

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Brought to you by the
Illinois Green Industry Association--the resource for industry professionals in Illinois--to provide garden tips to our valued gardening consumers in and surrounding Illinois.


“April showers bring May flowers”.

May truly is a month of beautiful flowers. May is also a time to start planning for the hotter, drier months that are sure to come!  The Illinois Certified Nursery Professional (ICN Pro) at your local garden center can help you plan a garden that will not only be beautiful in May, but it will also be beautiful during those long, hot, dog–days of summer.

May is prime gardening season--keep the following tips in mind when you are out enjoying the glorious spring days!


  • Now is the time to finish up fertilizer & weed spray applications! It is important that these applications be done before the temperatures start to heat up!

  • Remember to keep your mowing height up! A taller turf is a healthier turf, and a healthy turf is more able to withstand drought and compete with weeds!

  • If you are interested in installing an irrigation system for your lawn, be sure you contact a professional. For irrigation professionals your area contact the Illinois Green Industry Association at www.illinoisgreen.net/directory.


  • Now is the time to plant your annual flowers! The frost-free date for Central Illinois is May 15. That means that after May 15 you can feel very safe in setting your tender annuals outside. 

  • When potting your annuals, it is a good idea to use a time-release fertilizer in the container. There are several different time-release fertilizers, and different garden centers will stock different ones. Ask the ICN Pro at your local garden center for their professional recommendation.

  • Now is the time to plant your vegetable garden. Before planting your garden it is a good idea to incorporate an organic material into the soil. This will improve the soil that your plants are growing in, and it will also reduce the amount of synthetic fertilizers you need. After planting, you can use mulch to help control weed growth. If you have questions about maintaining your vegetable garden, visit the ICN Pro at your local garden center.

  • Beginning in May it is recommended to start feeding your roses. If you have hybrid tea, grandiflora, or floribunda roses they will benefit from regular feeding. You can use a rose food that has a systemic insecticide in it. The systemic insecticide will attack any chewing insects that decide to feast on your roses. If you have had black spot or powdery mildew on your roses in the past, you should begin your spray regime in May. There are two recommended products: 1) a systemic fungicide, or 2) a systemic fungicide mixed with a systemic insecticide. Beware that the use of these products is harmful to birds, butterflies and other desirable creatures, as well as the less desirable ones. Only spray when necessary!

  • For weed control in your landscape beds you can use a pre-emergent herbicide. A common product name is Preen (treflan). This is a granular formulation that can be applied with a spreader or a shaker can directly into the bed. This product helps prevent weed seed from germinating, it will not kill weeds that are already growing. To treat your existing weeds spot treat with a broad-spectrum herbicide like Round- Up or Killz- all.  

Water Garden

  • Your water garden will continue to come alive in May, after the danger of frost is past, your tropical plants may be added. Floaters, such as water hyacinth and water lettuce, can be added. For help with your other water gardening questions, visit the ICN Pro at your garden center.

Native Landscapes

  • If you are planning to install a native landscape in the future, it is very important to control the existing vegetation on the site. Before seeding in June, the area must be free of weeds.  A clean site can be achieved by using a contact herbicide, like Round–up. For more information on the establishment of native landscapes in your area, visit the ICN Pro at your local garden center.

Insect & Diseases

  • Towards the end of May, you’ll want to spray any young trees that you have for borers. All young trees are susceptible to borer damage and there is no cure. In order to prevent borer damage, you should spray your young trees in late May and again 2 weeks later (in Central Illinois). In the past, homeowners have been able to treat their young trees themselves with Dursban. However, Dursban is no longer available to homeowners. Check with your local ICN Pro for recommendations for your area. Most garden centers will have a spray program available.

Birds & Butterflies

  • Hang up your hummingbird feeders, and remember to clean and fill them often! 

  • Continue feeding your song birds! Black Oil Sunflower is perfect to feed your fine, feathered friends all year long! They will enjoy your generosity and you’ll enjoy their beauty!

  • Use chemicals in your lawn and garden with great caution!  Remember that chemicals are not ‘critter specific’! What kills an undesirable creature, like an aphid, will also kill a desirable creature, like a butterfly!

Get your garden growing beautifully, with help from an ICN Pro at your local garden center! Not sure where to find an ICN Pro in your area? To locate an ICN Pro in your area, simply log on to www.illinoisgreen.net and visit the ICN Pro Directory. There you will find a complete list of ICN Pro’s around the state!

More tips...

by Carey Boehm-Corrie, ICN Pro of the Year (2003), Boehm's Garden Center, Rushville, IL






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Springfield, IL  62704
217-546-GREEN (4733)

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