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Over the Garden Fence

More Early Spring FAQs: Lawns, Trees and Seeds

Emails to the office this time of year are always a mix of “When can I…?” or “Is it too late already to…?” kinds of questions. Here are three common examples:

Q: When should I be putting down crabgrass preventer?

A: Crabgrass along with other annual grasses will want to have soil temperatures greater than 55 to 60 degrees Fahrenheit (°F) for seven to 10 consecutive days and continues until soils reach 95°F. Other annual grasses germinate as soils get warmer than 60°F. That is likely to be 3 to 4 weeks away, depending on how Mother Nature behaves. Ideally, getting the product on the lawn just before that will give the longest time of protection. Too early and crabgrass can still show up. Putting the preventer down too late, you get the early crabgrass surviving while the later germination is prevented. Finally, consider management practices that favor the lawn, like mowing higher, with a sharp mower blade, as often as needed.

Q: I still need to do my dormant shrub pruning, am I too late.

A: As long as the shrubs remain dormant, you are good to go. Look to be sure growth has not already resumed for 2020. Bud swell is a good indicator that your shrubs (different shrubs resume growth at different times) are starting. That does not mean you cannot prune, it may limit how much of the branching structure you are going to be able to thin. Except for something early like Alpine currant, most other shrubs found in a typical home landscape should be fine yet, just do not wait too long.

A home orchard management reminder – Dormant oil sprays should be going on while temperatures are going to remain above freezing for at least 24 to 48 hours. We are having those kinds of windows right now and fruit trees need to be completely dormant so there is no injury.

 Q: How do I know when to start my vegetable and flower seeds indoors?

A: All seed packets are going to suggest seeds be started 4 to 6 weeks or so before they are to set outdoors. The trick here is estimating (or guessing?) when that date is going to be in your yard. The earliest and hardest vegetables can be sown directly in the garden or by transplants sometime in early April.  We normally are buying those transplants since they would have needed to be sown a few weeks ago.  While there are some frost tolerant vegetables (not there yet for the flowers) that can also be sown directly, most of the vegetables sown indoors are those considered tender and warm loving, along with our flower seeds. These transplants would be planted outside. Be successful by using new or very clean seed flats with a soil-less media and do not overwater the flat. A great reference for the garden library is Vegetable Gardening in the Midwest, a publication available through PubsPlus at the University of Illinois at

About the author: Richard Hentschel’s expertise extends across several subject areas with specialties in lawn care, fruit tree production, woody ornamentals, and home and community gardening. During his 45-year career in horticulture and agriculture, Hentschel became a well-known and respected expert for commercial and homeowner audiences, industry organizations, and media. He retired from University of Illinois Extension in April 2022 with nearly 30 years of service as a Horticulture Specialist and Educator in northern Illinois.