Early bloomers should be fine but keep mulch, leaves for now

With the recent warm weather, plants — and people — are acting like it’s spring. You might be seeing tulips and daffodils come up, and flowering early bulbs. Don’t worry; you don’t have to do anything special at this point, but you might want to just keep mulch and leaves on beds to help protect plants when any severe cold returns. It’s best to avoid working in beds with wet soil. At the Chicago Botanic Garden, we’ve started cutting back perennials and focusing on dormant pruning.

In my Highland Park neighborhood, I’ve seen deer browsing gardens. These animals may be more aggressive this spring as they look for plants to eat after the long winter. I’d suggest protecting emerging tulips from deer and rabbit damage by spraying them with a repellent or covering them with netting; any repellent should be reapplied after rain. As the bulbs grow, adjust the netting, and don’t forget to weigh it down on windy days. Just a reminder that deer and rabbits don’t typically eat daffodils and ornamental onions.

• If you’re outside more during the springlike weather, you might see more insects around. March is a good month to control insects, such as magnolia scale, with an application of dormant oil — but only do so if you have a problem with insects; don’t apply it as a precaution. Wait until temperatures are at least 40 degrees Fahrenheit with no chance of freezing weather or rain within the following 24 hours. Avoid spraying on windy days to prevent any spray drift. As with any product, please be sure to read the label to make sure the plants you’re treating won’t be damaged by the dormant oil spray. When used properly, dormant oils can be very effective with minimal impact on the environment.

• No matter what the weather does, this is an exciting time for gardeners, as planting season gets underway. You can get a jump on the season by starting 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. Please adjust your start dates accordingly, depending on where you live and the frost-free dates.

Heat mats under the pots can help with germination. Transplant tiny seedlings into slightly larger containers with a “growing on” mix when they have two sets of true leaves. Gradually introduce the small plants to outdoor conditions before planting to acclimatize them. They can be planted in containers or garden beds after the danger of frost has passed.

Thinking about juicy tomatoes already? Remember that tomatoes don’t like cold weather and will have stunted growth when conditions are too cold, so plant them later if the spring weather is cool.

• Tim Johnson is director of horticulture at Chicago Botanic Garden, chicagobotanic.org.