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May 2010 Garden Calendar

Contributors: Karen Jeannette, Yard and Garden News Editor
Including Excerpts from the 2010 Minnesota Gardening Calendar

This month Bob Mugaas tells us the crabgrass has emerged early (Home Lawn Care - Recapping the very early spring of 2010 and what's next for timely information about Lawns) and Jeff Hahn says Spring Insects are Early this year, too. Gardeners across the state have been inquiring if they can plant and perform other garden and yard tasks earlier than in past years. Below we provide advice for this gardening season come early.

Advice for the Gardening Season Come Early

When to Plant Flowers

Despite the warmer and earlier growing season, the answer to, "Is it safe to plant perennials and annuals?" is still "Wait until mid-to late May to plant perennials and until after your area is frost free before planting flowering most annuals."

Why Wait?  In most Minnesota locations, perennials can be planted after mid-month, but wait until you're certain there will be no more frost before adding flowering annuals to the garden. Most, including impatiens and geraniums, have no frost tolerance. Pansies, violas, and johnny jump-ups are among the few annuals that will not be killed or badly damaged by frost. Calendulas, snapdragons, and sweet alyssum may also be planted a little early. 

You can identify when your area is likely to be frost-free using the MN spring frost-free map:  

When to Plant Vegetables

Kale and other cool season vegetables can be
planted as soon as the garden bed is ready.
Karen Jeannette
Which vegetables can I plant and when? You can sow early "cool-season" crops such as lettuce, cabbage, cauliflower, broccoli, Brussels sprouts, and onions immediately after preparing your garden plot.

Warm season vegetables, like tomatoes and peppers should be planted after the last chance of frost.  See "Planting the Vegetable Garden": for guidance on when to plant and how far apart to space your vegetables.

Keep Up with Early Pests and Diseases

Plant Diagnostic Modules: Pictures, simple descriptions, and easy to follow management instructions make it easy to stay ahead or just keep up with plant pests and problems using any of the University of Minnesota Garden Info Diagnostics Modules:
Stay ahead of disease this year with diseases management tips in this month's article by Michelle Grabowski: Keeping Plants Healthy and Green While Going Green

When to Perform Lawn Care

The lawn care calendar guide "Upper Midwest Home Lawn Care for Cool Season Grasses" ( is a helpful guide for scheduling lawn maintenance. However, this month, learn how to adjust your lawn maintenance practices for this earlier than normal growing season with Bob Mugaas' timely article, Lawn Care: Recapping the very early spring of 2010 and what's next for timely information.

For more information on lawn care, see the University of Minnesota Garden Info lawns section:


Are you starting a raised bed? Ordering soil? Adding Compost? Find information on soil topics at the University of Minnesota Garden Info soils section:

You needn't test your garden soil annually, but if plants have grown poorly the past year or two, despite being in a sunny location and receiving normal care, visit U of M Soil Testing Lab web site: .  You'll get a questionnaire with instructions on taking and sending in samples, If the problem is due to a nutrient imbalance, excess alkalinity, or acidity, they'll suggest a remedy, with respect to what you are growing.

Small Fruits

If you'd like to grow some fruit in your yard, but don't have room for apple or pear trees, consider planting Minnesota-hardy blueberries, raspberries, or strawberries. You need an area well-drained soil and plenty of sunlight -- a minimum of six to ten hours daily. More is better. In addition, blueberries need acidic soil to thrive. Have your soil tested for specific information on acidifying your soil before planting them. For more information regarding fruit varieties and culture, see the Fruits section of the U of MN Gardening Information website:


See the Extension listings of garden tours, horticulture diagnostic clinics, workshops, and plant sales @

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