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Sunday, November 28, 2021

Winter gardening questions? URI’s Gardening Hotline has the answers

Calls, emails now answered year-round, seven days per week

By Todd McLeish

The University of Rhode Island’s Gardening and Environmental Hotline receives thousands of calls and emails each year about everything from planting flowers and vegetables to lawn care and controlling pests.

Due to increasing demand, the hotline is now open year-round with 21 Master Gardener volunteers answering questions seven days per week. Walk-in visitors to the Mallon Outreach Center in Kingston are welcome by appointment. Call 401-874-4836 and leave a message for a return call, or email for answers to your gardening questions.

            During the winter months, the type of questions the volunteers receive are quite different from those during the growing season. Here are the top 5 winter gardening questions and their answers.

How do I keep indoor plants healthy through the winter months?

Environmental conditions indoors during the winter months are often rather poor. Low light levels, cold drafts and low relative humidity are stressful to plants. These conditions may cause houseplants to shed a few leaves, but consistent care during the winter should keep plants healthy.

Master Gardener Alan Newton, one of the Gardening Hotline coordinators, said that sites near east and west facing windows are often best to assure adequate sunlight, except for plants such as African violets, which do best in north windows or under 12 hours of fluorescent lights.

“Make sure the plant is kept away from cold drafts or heat sources, and apply water until it begins to flow out the bottom of the pot,” he said. “Discard excess water and allow the soil surface to dry to the touch before watering again. Most houseplants do not need to be fertilized during the winter months.”

How do I control insect pests on indoor plants?

It’s not unusual for houseplants brought in from the outside or purchased from a store to have insects on them, so Newton recommends that plants be isolated for a week or two on an enclosed porch or in a closed room prior to being brought into an area where other houseplants are present. 

            “Thoroughly examine all plant parts and containers before bringing them home from the store or bringing them indoors,” he said. “A magnifying lens may be needed as some insects are quite small. Examine the tops and bottoms of the leaves and the stems for any holes, eggs, or webbings. Watch for any leaf discoloration, and look for sticky honeydew substances that could be an indication of aphids, mealybugs, or scale insects.”

Some insects like fungus gnats will move when the plants are watered. Yellow or blue sticky traps detect flying insects. If insects are present, the plants can be wiped down with a damp cloth, infected leaves can be pruned, the soil can be replaced by sterile soil, and some pests can be picked off. If these non-chemical methods do not eliminate the pests, most can be controlled by insecticidal soaps or neem oil. If all these efforts fail, it may be best to dispose of the plant rather than infect other house plants.

How should I care for trees and shrubs in winter?

It is important to continue watering trees and shrubs until the ground freezes, and check them for any diseased foliage, which should be discarded instead of composted. Do your best to protect trees and shrubs from heavy snow, and in February they should be inspected for branches that might benefit from pruning. Fruit trees are best pruned in March by removing dead or diseased branches while the trees are in a non-growing state.

For flowering shrubs, Newton said it is best to wait until they have flowered for pruning. Hydrangeas can be pruned in the winter or spring depending on the type. Climbing varieties require no pruning.

“With panicle or big-leaf hydrangea varieties, dead blooms can be pruned, but since they bloom on old and new wood, I usually wait until spring to differentiate between old wood and dead wood,” he said. “After establishment for two or three years, smooth varieties can be pruned to the ground in the spring. If you do not know the variety you have, it is best to wait until spring to prune.”

How and when should I start seeds growing indoors?

Many flowers and vegetables may be started from seeds indoors. Vigorous plants that are started indoors flower sooner and produce an earlier harvest than plants started outdoors. However, seeds of certain plants are best sown directly outdoors when weather conditions permit.

The time for sowing seeds indoors depends on the time required to develop a healthy transplant large enough to be successfully moved outdoors, Newton said. The range can be 3 to 15 weeks depending on the plants and the cultural conditions in the home. Information on seed packets can serve as a guide, or visit URI’s online planting calendar (

Seeds should be planted in a loose, well-drained, and fine-textured medium. Vermiculite, sphagnum moss, and soilless mixtures are ideal for starting seeds. Initial containers should be small, and they should be sterilized and free of chemicals if previously used. When planted, they will need warmth but not light. Temperatures should be kept between 60° and 65°F, and they should be kept moist but not drowned. Once sprouts appear, light is important, whether sunlight or artificial light. Seedlings require approximately 15 hours of light, and they should be fertilized lightly and transplanted to larger pots, as needed, before sowing outdoors.

Two seed-planting videos are available on the URI Cooperative Extension YouTube channel.

How should I prepare my garden for spring?

Winter is the time for preparing and planning for the gardening season. It’s a good time to inspect, clean, repair, or purchase gardening tools. Tools should be sanitized with a 10% bleach solution and sharpened as needed.

Winter is also time to review the past year for what grew well and what did not, Newton said. What plants succumbed to disease? What plants might be moved for more advantageous growing conditions? If the soil has not yet frozen, winter is also an optimal time for sending soil samples to the University of Connecticut or University of Massachusetts for nutrient analysis to avoid the spring rush. And if weather permits, winter is an opportune time to prune out invasive plants, as it is often easier to navigate spaces with dense foliage and growth.

Other common winter questions address what plants to plant for certain conditions. The Rhode Island Native Plant Guide ( and the Coastal Plant Guide ( have filters enabling users to select for conditions like sun requirements, moisture, and size. They provide extensive lists of native plants that thrive in New England soils.

The URI Hotline can also provide guidance for plantings for specific situations, such as soil textures, wildlife resistance, or ground covers.