Most gardeners are fond of their hydrangea shrubs, whether they plant the pom-pom variety with globes of flower clusters or shrubs with panicles or lacecap flowers. Hydrangea cold tolerance varies among varieties, so you may need to think about winterizing hydrangea plants. Winter kill on hydrangeas is not a pretty sight. Learn how to protect hydrangeas from the cold in this article.
Hydrangea Cold Tolerance
Hydrangeas are among the easiest shrubs to grow. Easy care and undemanding, hydrangeas decorate your garden with their big, bold flowers for months on end. When summer ends and winter sneaks in, it’s important to know how to protect hydrangeas from cold, and this involves hydrangea cold tolerance. Some varieties, like smooth hydrangea (“Annabelle”) and panicle, or PG hydrangea, are very cold-hardy and bloom on new wood. If these are the species in your garden, you don’t have to worry about winter kill on hydrangea. They don’t need protection unless the temperature dips below negative 30 degrees F. (-34 C.). Generally, leaving the old growth over winter, which can serve as additional winter interest, also helps protect these plants. All of the other hydrangea varieties, including the popular big leaf, form flowers during the previous growing season. These young buds need to survive the winter for you to see blossoms the following summer. If you are planting big leaf or one of the other varieties that bloom on old wood, you’ll want to learn about preventing winter kill on hydrangeas.
Winter Kill on Hydrangeas
Winter temperatures, as well as winter winds, can cause winter kill. This general term just means plant death during the winter season. The low winter temperatures can kill the plant, or they might die because of drying out caused by winds. Since hydrangeas go dormant during the winter, you may not notice winter kill on hydrangeas until spring. Your first hint of damage may be the fact that no green shoots emerge from your hydrangea in March or April. Preventing winter kill in hydrangeas is a matter of protecting the shrubs, including their nascent buds, from winter’s wrath. A good way to start winterizing hydrangeas is to lay down a thick layer of mulch over their root area. Straw works well for this. For even greater protection, cover the shrub with a wire cage, or build a cage around it with strong stakes and chicken wire. Wrap burlap or insulation cloth around the cage. You’ll also want to water the plant generously just before the ground freezes.
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Teo Spengler has been gardening for 30 years. She is a docent at the San Francisco Botanical Garden. Her passion is trees, 250 of which she has planted on her land in France.
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