Caring For Hostas In The Winter: How To Winterize Hostas

Hostas (​‌Hosta‌​ spp.) make an appearance in many gardens and shady landscape areas because they're easy to grow and add beautiful greenery to the space. Winterizing both garden-grown and container-grown hostas in the fall prevents root damage to keep your garden greenery thriving the following year. They'll reward you for this extra winter care with lush new foliage in the spring and showy flowers in the summer. Though hostas are fairly cold hardy, it's still important to protect them from the worst winter weather. Learn how to winterize your hostas so you can enjoy them again come early spring.

Hostas can survive winter temperatures as low as -40 degrees Fahrenheit when planted in the ground, and they are hardy in USDA zones 3a to 9a.

Damage occurs to the root system when temperatures fluctuate. This is a bigger problem for hostas newly planted in the fall because they haven't had a chance to grow their roots deep into the ground, but damage can occur in established hostas too. As the ground goes through thaws and freezes, it pushes or heaves up the hostas, exposing their roots to the elements.

Hostas will come back healthier next spring if you take proper care of them during the colder months. Start preparing hostas for overwintering at the end of summer. Here's how to winterize hostas in the ground:

1. Continue Watering

Water hostas with about 1 inch of water through fall, but stop fertilizing the plants in later summer to stop new leaf growth, which makes the plants more susceptible to winter damage.

Trim the hosta stems down to the ground in late fall to prevent crown rot and to discourage rodents and slugs from adopting the pile for winter shelter. Whenever you groom hostas, clean shears and wipe cutting surfaces with rubbing alcohol to guard against transmission of fungal infections or rots.

Cover the hostas with shredded mulch in the fall after the ground freezes to a depth of 3 inches. The mulch application will help insulate the soil, reduce the severity of temperature fluctuations, and protect the crowns of the plants. A layer of mulch will also deter the growth of weeds while the hostas are dormant, meaning unwanted plants won't leach nutrients from the soil.

In the winter, water hostas about once a month. "Once in winter sleep, the plants will depend on their internal storage for moisture, so it's important to replenish it once in a while," Kevi Tara, owner of the plant nursery LEAF n JOY, advises Hunker. "Just make sure that you water your dormant hostas early in the morning so that moisture can be replenished before night comes and potential frost returns."

Hostas grown in containers are more vulnerable to extreme temperature fluctuations than those planted in the ground. When the soil around dormant hostas repeatedly freezes and thaws, moisture in the dirt expands and contracts. This results in plant roots being pushed to the surface in a process called heaving. Mulching around the container helps to stabilize the soil temperature when wintering hostas. Here's the best way to winterize container hostas:

1. Water the Hosta Container

Before the first hard freeze hits, thoroughly water the container hostas to help the plants survive until spring.

Prune the hosta stems all the way to the soil. As the hosta approaches dormancy, its leaves will turn yellow. Tara suggests waiting until the leaves turn brown and crispy to make sure the hostas have as much opportunity as possible to absorb vital nutrients before the dormant period.

When the first frost arrives, "Move your hosta containers to a sheltered spot, like under a porch or deck," says Lindsey Hyland, horticultural expert and and founder of Urban Organic Yield. "This will help protect them from the wind and snow."

Add an insulating layer around your containers using bubble wrap, Styrofoam peanuts, or even old newspapers. This will help keep the soil from freezing solid. If your garden space allows, digging and placing hosta containers in the ground is also an effective way to insulate.

When the spring season arrives, place your potted hostas in the desired location, preferably shady spot in the garden. Divide and re-pot container hostas every five years.

Remember that hostas are a hardy perennial, and they need to feel the chill of winter to come back in the spring. The American Hosta Society clarifies that most hostas require 600 to 700 hours at less than 40 degrees Fahrenheit to come back the next spring, but more cold dormancy time means stronger plants. So, there's no need to completely provide hostas with winter protection because Mother Nature has adapted them to survive the cold.

If you don't winterize hostas, there's a chance that temperature fluctuations in the soil will heave the hosta root system to the surface before the warmth of spring. Leaving the dead foliage on the plants through the winter may attract rodents (such as voles) and other pests that can damage the plants.

Otherwise, hosta plants have a good chance of making it to the next growing season without too much extra winterizing preparation. However, as Tara points out, a little support from the gardener can make all the difference to the hosta's vitality next year.

"Not winterizing hostas before the winter season might result in weak plants next year that are just barely making it and instead of being a garden stunner, rather invoke feelings of sadness and pity," says Tara. "No one wants sad hostas in their garden, so trust me, the extra effort is worth it."