Timely Tips

What to Do in December 2025
Weekly Gardening Timely Tips from
Cornell Cooperative Extension of Westchester County

Nov. 30 to Dec. 6

Perennials: As long as the ground’s not frozen, keep planting spring bulbs. Perennial mums may benefit from a loose cover of mulch after they have finished flowering as the ground begins to freeze.

Flowers: Crocus and hyacinths bloom in mid-winter if you pot the bulbs in clean pots with a well-drained potting mix now. If the bulbs are not pre-chilled, they’ll need to receive a cold period (35° to 45°F) for 12 to 14 weeks to trigger flowering. Pre-chilled bulbs should be stored in a cool (55° to 65°F) protected place that will be accessible in winter. Pot up the bulbs 3 to 4 weeks before you’d like to see flowers. Keep the pots in a cool (60°F) well-lit room and resume watering during this pre-flowering period.

Fruits and Vegetables: Protect remaining kale, spinach and other cool season crops from freezing with plastic sheeting or a cold frame. Make sure the cold frame or plastic can be vented on sunny days to keep plants from heating up too much or putting on tender growth that may freeze later. Remove any remaining fallen fruit under bearing trees.

Trees and Shrubs: Once the leaves are down, clear out roof gutters. Continue to remove dead or damaged wood from trees and shrubs to minimize additional damage after winter storms. Oaks may be pruned at this time. Contact an arborist for work on large trees.

Lawns: Before putting the mower away for the season, sharpen the blade (or have this done by a professional) so this task doesn’t await you in the spring. If using a gas mower, change the oil, spark plug and air filter. If using a fertilizer spreader, clean and put it away. New York State law prohibits the application of lawn fertilizer between December 1 and April 1. (Early fall is the best time to fertilize the lawn anyway.) Continue to remove sticks and other debris. Stay off frozen grass and don’t allow people to park on the lawn at any time.

Houseplants: Overwatering often leads to root rot and is the biggest killer of houseplants. When watering, it’s better to do this thoroughly but less frequently, based on the plants’ individual needs. Allow the overflow to drain out of the bottom of the pot and wait until the top of the soil dries before watering again. If watering frequently but just enough to moisten the soil, salt deposits can build up.

General: Here’s a great holiday gift for the gardener in your life:a subscription to the Home Garden Lecture Series through Cornell Cooperative Extension of Westchester. There is one webinar lecture per month from January through May, and a tour in May while space lasts. Advance registration is required. The whole webinar series is $45; individual webinars are $5 each. Check out the brochure at https://www.canva.com/design/DAG37gykNic/RGq-kIdH95APY6-bKoGQYw/view?utm_content=DAG37gykNic&utm_campaign=designshare&utm_medium=link2&utm_source=uniquelinks&utlId=hcc45ab7c29 For more information, please call CCE at 914-285-4640, 914-285-4620 or email westchester@cornell.edu

Last updated November 29, 2025