March 27

Perennials: As newgrowth appears, begin to carefully loosen winter mulch that may impede the emergence of plants that are poking through. Work lightly as there may still be beneficial insects wintering over in the duff. Minimize problems with leaf spots on by clearing out old diseased foliage before new shoots enlarge. Check iris rhizomes and remove any damaged by iris borers.

Flowers: Pansies may be planted in garden beds or outdoor pots now if the soil temperature is above 40°F at a depth of 2 inches, and nighttime air temperatures are above 25°F. Other flowers that grow best in cool weather and tolerate light frost when fully acclimated include alyssum, calendula, dusty miller, snapdragon, and sweet William.

Fruits and Vegetables: Start seeds of eggplant, peppers, and other slow-growing tender crops indoors, following seed packet or catalog instructions. Begin to acclimate hardy cool season vegetables to outdoor conditions so they are ready to plant when the garden soil is workable. (If it’s dry enough to crumble in your hand when you form a ball, it’s ready.) These include collards, kale, lettuce and Swiss chard. You can also continue to direct seed or plant successions of early crops, such beets, carrots, collards and kale, lettuce, mustard, peas, radishes, Swiss chard, turnips, and others.

Trees and Shrubs: Finish pruning oak trees before sap beetles that carry oak wilt spores become active. This will help reduce the spread of this deadly fungal disease with no known treatment. Sap beetles are attracted to fresh tree wounds and oozing sap on healthy oaks in spring. Contact an arborist for work on large trees.

Lawns: Continue to remove twigs and other debris. As the soil warms to 50°F at a depth of 2 inches, seed bare spots and overseed areas of thin turf that receive at least 4 hours of direct sunlight. In places with less than 4 hours of direct sunlight, consider using a shade tolerant groundcover instead. Contact your local Cooperative Extension for advice.

Houseplants: If you bring in a new houseplant, isolate it from others for a month. Check it approximately once a week for diseases and insects. Consider discarding plants that are heavily infested. To manage problems you may find, and advice on how to prevent spread to other plants, contact your local Cooperative Extension.

General: How do you transform a thirsty garden into one that doesn’t need extra water? Come to next month’s Cornell Cooperative Extension of Westchester 30^th Home Garden Lecture Series: Water Wise Gardening, Wednesday, April 12, 2023, from 10:00 to 11:00 am, remote on Zoom, $5.
Speaker: Kristen Ossmann. She will explore ideal plant selection, xeriscaping and rain gardens that provide financial and natural resource savings. Learn to implement these waterwise practices on your site. For more information, contact westchester@cornell.edu or 914-285-4620.