Get a jump on insect control in March
March is a good month to control insects such as magnolia scale with an application of dormant oil.
Verify you have a problem insect before pursuing any controls and avoid applying treatments only as a precaution to make sure insects will not be present.
To properly apply dormant oil, temperatures should be at least 40 degrees with no chance of freezing or rain within the following 24 hours. Avoid spraying on windy days to prevent any drift of the spray.
As with any product, be sure to read the label to make sure the plants you are treating will not be damaged by the dormant oil spray. For example, oils can discolor many conifers that have a bluish, waxy coating on their needles. The blue color will return on new unsprayed growth.
Dormant oils can be very effective with minimal impact on the environment when used properly.
• Prune fruit trees and grapes, as the worst of the winter cold has passed and spring growth has not yet begun.
• Start seeds of warm-season annuals and vegetables in a moist, soilless seed mix. These seeds should be started six to eight weeks before the last spring frost date, which is May 15 at the Chicago Botanic Garden. Adjust your start dates accordingly if frost-free dates are earlier or later where you live.
Transplant tiny seedlings into a growing-on mix in slightly larger containers when they have two sets of true leaves. Gradually introduce the small plants to outdoor conditions before planting in the garden to acclimate them to outside conditions.
They can be replanted in containers or garden beds after the danger of frost has passed. Tomatoes do not like cold weather at all, so it is best to plant at a later date if the spring is cool.
• Bulbs are beginning to grow with the recent warm weather. Spray tulip foliage with a deer repellent if you have deer in your neighborhood to prevent damage. Reapply after rain. Otherwise, there is nothing special to do for the bulbs, which are getting an early start this year.
• Tim Johnson is director of horticulture at Chicago Botanic Garden, chicagobotanic.org.