Time to address several good questions that Master Gardeners have gotten already this early spring. We are right on schedule for some; others will have to wait, being weather dependent.
Q: I need to trim my oaks and maples. Do I do it now or wait?
A: We have about two weeks (by mid-April) to do our dormant pruning while there is no sap flow. If you have elm in the home landscape, it is another tree that should be pruned while dormant. For oaks and elms, we want to do so to prevent the spread of wilts by the beetles that are attracted to the sap. Maples will “bleed” excessively once sap flow starts, so dormant pruning is recommended.
Q: What is the best time to put down crabgrass preventer?
A: The soil temperatures remain too cold for crabgrass seed to germinate. With our current weather pattern, it is likely going to be sometime in mid-April this year. Crabgrass is an annual grassy weed that will need several days and nights where the soil temperatures are above 55 degrees. Crabgrass will continue to germinate over a several-week period. If there has been a lot of crabgrass pressure in your lawn in the past, consider a second application mid-June. Lastly, crabgrass is a bit of an opportunist; it just needs bare ground or thinned turf to germinate and grow. Work on getting the lawn healthy and thick and you will have less crabgrass.
Q: When can I apply dormant oil to my home orchard?
A: Dormant oils are used to control overwintering insect adults, eggs and certain kinds of scale insects on your fruit trees. Thorough coverage is critical if you expect good control. Dormant oils are mixed with water for application, so most labels will state the proper conditions for application. This is usually when we will have above freezing temperatures for 24 to 48 hours. Always read and follow label instructions.
Q: Some of my landscape plants look burnt. Is there something I should be doing?
A: Minor winter burn should be expected on our needle and broadleaved plants. At some point during the winter, those leaves lost moisture and usually the outer edges can turn brown in response. The more leaf moisture lost, the more the leaf will turn brown. If it is just the needles and leaves, there is a bud just waiting to emerge and take over. Browned needles and leaves will naturally drop. If the desiccation has moved into small twigs and branches, there may be some cleanup needed with hand pruners. Prune back to a viable bud or twig. Be sure the plants have water available early in the season and for next year; plan to water one more time as late as possible in the season. Some plants – like the groundcover Pachysandra, also known as Japanese spurge – benefit from annual applications of organic matter to protect shallow fleshy roots and provide an ongoing source of nutrition.
We are all excited spring is happening, yet Mother Nature is still in control, so gardening patience is in order.
• Richard Hentschel is a horticulture educator with University of Illinois Extension, serving DuPage, Kane and Kendall counties. Get more garden and yard updates with This Week in the Garden videos at facebook.com/extensiondkk/videos and the Green Side Up podcast at go.illinois.edu/greensideup.