Winter Plant Care – How To Keep Plants Alive Over Winter

By: Victoria Blackstone

You’re likely accustomed to leaving potted plants out over summer, but if some of your favorite perennial plants are frost tender where you live, they’ll be damaged or killed if you leave them outside during winter. But by bringing plants indoors for the winter, you can protect them against the harmful consequences of cold weather. After bringing plants indoors, however, the key to keeping plants alive over winter depends on what type of plants you have and the growing environment you provide them.

Winter Plant Care

How to keep plants alive over winter (by overwintering plants in pots indoors) means you first have to make room for the plants, which is sometimes easier said than done. Although you may have enough room in certain locations in your house, if the plants don’t receive enough light, they may begin to decline.

Tip: Before bringing plants indoors, install some hanging basket hooks or shelves in front of bright windows. You’ll have an overhead winter garden that keeps plants from cluttering your floor space.

Other than giving your plants sufficient light while they’re indoors, a key to keeping plants alive through winter is providing the temperature and humidity they need. If you place the pots near a heating vent or a drafty window, the fluctuations in temperature may place too much stress on plants.

To increase the humidity around plants, set the pots on top of pebbles in a water-filled tray or dish, and keep the water level below the base of the containers.

When to Start Overwintering Plants in Pots

Most houseplants are tropical plants, which enjoy a little “summer vacation” in pots on your patio or deck. However, when the nighttime temperatures dip to 50 degrees F. (10 C.), it’s time to start bringing plants indoors to keep them alive during the winter.

Caladiums, lilies and plants that grow from bulbs, tubers and other bulb-like structures, may go through a “resting period.” After an active growth period, some plant’s leaves and stems begin to fade or turn yellow, and the plant typically dies all the way to the ground.

Even though these plants go through a dormant stage in winter, some (such as caladiums) need warm winter plant care while others (such as dahlias) respond better to chillier temperatures. A heated closet inside your home is suitable for overwintering caladium tubers, but an unheated location (40-50 degrees F. or 4-10 degrees C.) will work better for dahlias.

Before bringing in your entire garden of plants for the winter, know your USDA plant hardiness zone. This determines the lowest temperature at which different plants will survive the winter outside. When you buy plants, look on the manufacturer’s tag to find the hardiness information.

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Overwintering Herbs

I've enjoyed harvesting fresh basil, parsley, and fennel from my garden all summer. Now that fall has arrived, it's easy to forget about those fresh herbs and resign myself to cooking with dried herbs. But I'm not giving up just yet. Some herb plants can be brought indoors to grow for months, providing summer flavor for my cooking. Others can be protected in the garden over the winter and they will bounce back next spring.

Here are some suggestions for keeping herbs through the winter -- indoors and out.

Protect Perennial Herbs

Herb plants can be annual, biennial, or perennial. Perennial herbs, such as chives, lavender, oregano, thyme, overwinter well in the ground. In most areas simply wait until a few hard freezes and then cut back tall herbs to within 4 to 6 inches of the ground. In cold winter areas (USDA zones 3-5), add a 2- to 3-inch-thick layer of shredded bark mulch on top of the herbs for added protection. The bark will prevent the ground from freezing and thawing in winter, making it less likely the herb roots will heave out of the ground, desiccate, and die.

You can enjoy tender perennial herbs such as rosemary, and biennial herbs such as parsley, all winter long by potting them up and bringing them indoors for the winter. Here's how.

Dig parsley plants now, making sure to get most of the root system. Pot them in deep containers, water well, and leave them outdoors for a few weeks in a shaded area to recover from transplant shock. Once they've revived, bring the plants indoors before a hard freeze and place them in a sunny window. You should be able to harvest fresh parsley leaves all fall, and if the plant gets enough light, it will even produce new growth. However, by late winter the leaf quality will decrease as the plant gets ready to produce a seed stalk. At that time simply compost the plant.

Most rosemary varieties are hardy to USDA zone 7, perhaps even zone 6 with protection. In colder areas you'll have to bring your plant indoors to survive the winter. Pot it up and allow time for it to adjust to container life. Bring it indoors before a hard freeze and place it in a sunny southern window. Rosemary likes cool temperatures, high humidity, and barely moist soil in winter. Place the plant in a 50- to 60-degree F room. Keep the humidity high by misting often, and place the pot on a pebble tray filled with water. Water the pot just enough to keep the soil from drying out. Your plant may not grow much in winter, but it should survive and be ready to go outdoors next spring. Plus, you'll have the fragrance and taste of fresh rosemary in your kitchen all winter.

You also can bring hardy herbs indoors in pots, not for their protection but for your use. Herbs such as thyme, oregano, and mint can spend the winters indoors in pots to provide fresh leaves for cooking while the snow flies. Simply move them back outdoors in spring and plant them in the garden.

If you don't have room to bring in a large potted plant, take cuttings of rosemary, lavender, pineapple sage, and other woody perennial herbs. Root the 4- to 6-inch-long cuttings by dipping the cut ends in a rooting hormone powder. Stick the cuttings in a pot filled with moistened vermiculite or sand, cover the pot with a clear plastic bag with slits in it, and keep it in a warm, bright room out of direct sunlight. Once rooted, the cuttings can be transplanted into individual pots and grown under lights all winter. Not only will you have fresh herbs to eat, you'll have some new plants to grow in your garden next spring.

While annual herbs such as basil need to be sown each spring, some herbs will do the sowing themselves and come back year after year. Culinary herbs that readily self sow include coriander and dill.

Collect the seeds now and store them in glass jars in a cool location. Sow them next spring. You also can allow the seeds to naturally drop to the ground in the garden and self sow on their own. The seeds will sprout in fall or early spring, depending on your location. In warm-winter areas you may have a continual supply of these herbs throughout the winter depending on the weather.

Charlie Nardozzi is an award winning, nationally recognized garden writer, speaker, radio, and television personality. He has worked for more than 30 years bringing expert gardening information to home gardeners through radio, television, talks, tours, on-line, and the printed page. Charlie delights in making gardening information simple, easy, fun and accessible to everyone. He's the author of 6 books, has three radio shows in New England and a TV show. He leads Garden Tours around the world and consults with organizations and companies about gardening programs. See more about him at Gardening With Charlie.

Learn how to properly overwinter your garden plants to keep them protected from snow, wind, and freezing temperatures. From herbs to geraniums to roses to tropical plants, we’ll help your plants survive the winter. They’ll thank you in the spring!

How to Overwinter Geraniums

Before the first frost (find frost dates for your region here), cut plants back to about 6 to 8 inches. Then lift the plants and cut back the roots. Put the trimmed plants in the smallest pots possible—containers just large enough to fit the roots. Fill the remaining space in the pot with regular potting soil. Keep the plants in the shade for a week and then place them in a sunny spot indoors. When new growth starts, cut off all the old leaves.

How to Overwinter Rosemary

This culinary herb prefers life in a pot and can successfully survive as a houseplant from year to year.

Before a frost in the fall, dig it up, plant it in a pot, and bring it indoors. Place it in a sunny window and keep it evenly watered. Mist the leaves frequently or place the entire plant in the shower and give it a good rinse once a month. The plant may start to look a little tired by March, but it will perk up once you return it to the garden. Dig a hole in the late spring, after all danger of frost has passed, and set the plant back into the soil.

How to Overwinter Roses

Roses need thick insulation to help them stay dormant. For those that are grafted, such as hybrid teas, make sure that their graft unions are covered with soil to insulate them from low temperatures. After a freeze or two, mound 12 inches of soil around the base of the rosebush.

Nongrafted roses, such as rugosas and antiques, don’t need much protection. Just mulch the ground around them with a couple of inches of straw or shredded leaves.

All climbing roses need to be protected. Pull down the canes, lay them on the ground, and cover them with at least 6 inches of soil. Mound soil around the plant base, too. If your winter temperatures go below –10°F, leave canes in place and insulate them with a thick covering of straw wrapped with burlap or old sheets.

How to Overwinter Perennials

To encourage your perennials, especially new plants, to go dormant and stay that way through the inevitable freezing and thawing cycles of winter, you may apply mulch of straw, leaves, or other organic matter after the first several hard frosts. If you mulch the ground too early in the fall, rodents may find the cozy layer impossible to resist and the mulch may also delay the ground from freezing solid. See our article on getting your perennial garden ready for winter.

How to Overwinter Tropical Plants

Many tropical plants grow from underground bulbs, corms, or tubers, including caladium, calla lily, canna, dahlia, ginger, and tuberous begonia. These plants are easy to overwinter. When nights drop into the low 40s or high 30s F, the leaves of plants will brown and begin to die. This is your cue to dig, or lift, them up. (You can wait until after a killing frost to dig dahlias and cannas.)

Remove the dirt from the swollen portions of the roots and set them on newspapers in a shaded area or the garage to cure for a couple of days. Cut off the top growth and pack the bulbs, corms, and tubers in a box filled with dry peat moss or vermiculite. Store in a dark area where the temperature is between 35° and 50°F.

When spring arrives, plant again for another year of enjoyment. Bulbous tropicals will increase their numbers and produce bigger bulbs, corms, and tubers when they are saved from year to year in this manner.

Extra-Hardy Tropical Options

These plants can take colder temperatures than others in their class. The temperature given is what the plant can survive without protection. You can gain another 5 to 10 degrees of cold tolerance if you mulch heavily, plant in a sheltered area, and wrap plants.

  • Bananas: Musa basjoo (–5ºF)
  • Citrus: ‘Satsuma’ tangerine, ‘Meyer’ lemon, ‘Trifoliate’ orange (20ºF)
  • Figs: ‘Celeste,’ ‘Italian Honey,’ ‘Hardy Chicago,’ ‘Brown Turkey,’ ‘Petite Negra’ (10ºF)
  • Passionflowers: Incense passionflower, Passiflora incarnata (–10ºF)

How to Overwinter Trees

Protect a small tree or shrub from extreme cold and the uneven temperatures of freezing and thawing by surrounding it with a cylinder of snow fencing or chicken wire. Fill the space between the tree and the fencing with straw or leaves for insulation.

To shield a dwarf or young evergreen from winter damage, drive stakes into the ground at four corners around the plant. Wrap burlap or heavy black plastic around the stakes and secure it at the top, bottom, and center with stout twine.

Find the Right Place

A pot's location also determines how well plants are protected. Place containers on the north or east sides of the house where conditions are typically shadier. Southern exposures tend to have the greatest temperature swing.

Hardy dwarf conifers, evergreens, ornamental grasses and trees or shrubs with interesting habits or bark colors are great for adding winter interest. If possible, place pots with these plants near a window or front door where they'll be easily seen.

Right plant, right place

You might have come across the saying ‘right plant, right place’ already it’s a key element of good garden design, and is often mentioned in gardening programmes and magazines. It’s a simple but powerful approach to helping your plants thrive, and it’s well worth taking a little bit of time to understand the concept.

All plants – regardless of what you grow them in – have their own set of conditions that they will thrive in. Put your plant somewhere that provides these conditions, and you’re already well on the way to making it happy.

The flip side of this idea is that by forcing a plant to grow in conditions it doesn’t naturally enjoy, you will automatically limit how well it does.

The ‘right plant, right place’ concept goes a long way towards explaining why you might have lost plants in the past, and also gives you a simple framework for growing your plants going forward.

So how do you work out the conditions that your plants need? First of all, check the care label. If you don’t have one, look the plant up online, or use a plant identification app. Some plants need full sun, while others are happy growing in full shade. Your plant may need a high humidity level, or love to bake in dry heat. Once you’re armed with this information, you can choose the perfect spot for your container and make sure you’ve given your plants the best possible chance of doing well.

Tips for keeping rosemary alive through winter

Rosemary is a wonderful herb. It looks great, smells wonderful and is versatile in the kitchen and, during the summer, it's easy to grow. However, once the weather gets cold, many gardeners have problems with it.

While it seems resistant to the cold, easily surviving the hardest frost, there is not, as far as I know, any rosemary that is reliably hardy in our area. There are a few, like Hill Hardy, that will survive a warm winter and, if your rosemary is in a very protected area, you may be lucky enough to have other varieties survive.

However, for the rest of us, there are only two options. Either grow rosemary as an annual or bring it in about mid- to late-November and winter it over. If the plant is too big, make cuttings in late summer and winter over the much smaller cuttings instead of the mother plant.

If you choose to winter-over rosemary, ideally you grew it in a container. If you didn't, then about late-August to early September, you should have potted up the plants you wanted to save. If your rosemary is still outside in the ground, you can try potting it up now. However, by waiting this late you are adding the stress of transplanting to the stress of moving the plant indoors.

If you don't have any rosemary, you're still in luck. Rosemary has become a popular holiday decoration, most often pruned into the shape of a Christmas tree. Although I find that these plants are not quite as healthy and happy as one from the garden, they do OK with just a bit more attention.

The biggest problem with rosemary is the great die-off that occurs about February.

In most homes, our indoor-heating systems dry out the air, dropping the humidity well below what rosemary needs. Compensate by running a humidifier all your plants will be grateful. Raising the humidity also relieves that dry-nose feeling and annoying static electricity we experience in the winter.

Another option for improving the humidity around your plants is to create humidity trays. Fill the drip trays under your plants with coarse gravel or stones and keep a bit of water in the trays. Evaporation increases the humidity in the air surrounding the plant. If it's really dry, consider misting your plants. A quick spray once or twice a day may solve the dry air problem. You don't need humidity to be high, just comfortable, and increasing the humidity to about 45 to 55 percent in the winter increases the amount of heat the air holds. In rooms with similar temperatures, the one with higher humidity will feel warmer. Think how much hotter you feel on a humid summer day than a dry day with the same temperature.

So what else does your rosemary need to survive the winter indoors?

Light: Outside, your plant got six to eight hours of direct sunlight and loved it. So give your rosemary as much light as possible. A bright south-facing window is ideal.

Water: Rosemary can be a bit touchy about water. Too much or poor draining soil creates root rot. Too dry and the roots start to die. Water when the soil dries out at the surface ideal is evenly moist, never wet or dry soil. Be sure to use a pot that drains, and empty excess water from the drain saucer unless the pot is raised above a layer of gravel to create a humidity tray.

Temperature: While rosemary survives below 30 degrees outside, inside keep the temperature in the 55 to 80 degree range. About 60 to 65 degrees is best.

Air circulation: While not something usually mentioned, air circulation is important. Stagnant air allows mold and mildew spores to settle on plant leaves. Since powdery mildew is one of the most common problems with rosemary, air circulation is important. Use a small fan for a few hours daily to improve the air circulation and reduce mildew problems.

A reader's solution

Myra Bond is a friend and Northampton County master gardener. She sent a note on her methods for drying herbs. They offer some additional options to the ones listed in a recent column:

When I was a member of the Herb Society they gave a few easy tips on drying herbs. If you want to dry herbs in the summer, you could put newspaper on the rear shelf of your car. Spread the herbs you want to dry on the newspaper, roll up the windows and park your car in the sun. They will dry quickly and also make your car smell great.

The method I use is to cut the herbs to dry. I put them in a paper lunch bag (plain brown bag), I usually paper clip the bag closed, then put it in my frost-free refrigerator. Periodically check the bag. When the herbs are dry you can crush them or store them in a glass container — no fuss no muss. I also noticed that the herbs don't lose their color.

Sue Kittek is a freelance garden columnist, writer, and lecturer. Send questions to Garden Keeper at [email protected] or mail: Garden Keeper, The Morning Call, P.O. Box 1260, Allentown, PA 18105.

oFinish up planting: Spring-flowering bulbs, perennials, shrubs and trees, garlic, shallots, asparagus and rhubarb.

oSow seeds that need a cold period for germination, poppies, for example.

oPurchase gifts and gift cards for gardeners on your lists.

oCollect garden chemicals and store safely indoors. Check effective dates and properly discard old ones.

oUnpack and check holiday displays. Replace or repair damaged items in preparation for installing later this month.

oMark the edges of beds and locations of plants to avoid unintentional damage when installing holiday decorations, de-icing products, piles of snow or ill-aimed snow plows.

oProtect plants from damage when installing holiday lighting. Use only outdoor approved lights in outdoor displays.

oDig holes now if you are purchasing a live potted or burlapped Christmas tree. Find an appropriate spot to plant it and dig out the soil before the ground freezes. Store the soil, covered in a container in a garage or storage area.

oStart amaryllis bulbs now or about 8 to 10 weeks before you want them to flower. Make sure to allow bulbs that summered outside to rest in a dark area without watering before initiating bloom.

oAllow seed heads to remain on plants. They provide food for birds and small mammals during the leaner fall and winter months.

oDig and store tender bulbs after foliage is killed by frost.

oRake, blow or mulch leaves that fall on lawns to prevent mold problems that can thrive in matted leaves.

oBring in or wrap statuary and large pots to avoid winter damage.

oConsider using a humidifier, humidity tray or other means to increase the humidity around your indoor plants.

o Order or buy mulch for winter mulching but do not apply until after the ground freezes.

oPull out and compost healthy spent plants discard, bury or burn diseased or infested plants.

oContinue to water newly seeded areas until the ground freezes.

oWater any newly planted trees or shrubs any week when we receive less than an inch of rain. Regular watering is essential as the plants settle in and reestablish their roots. Continue watering as needed until the ground has frozen.

oCheck caulking around doors and windows, repair as needed.

oDump standing water and remove anything where rainwater can collect in stagnant pools.

oClean and repair gutters and down spouting.

oCheck and repair hoses before storing for the winter. Be sure to drain them and properly disconnect from faucets. Freeze proof outside faucets are a good investment to prevent frozen pipe issues.

oProvide and check deer, rabbit and groundhog protection for vulnerable plants. Reapply taste or scent deterrents.

oClean bird feeders, feed birds regularly and provide fresh water. Clean up spilled seed and empty hulls.

•Tools, equipment, and supplies

oCheck rakes, leaf blowers, mulching equipment and other fall tools. Schedule repairs and purchase replacements. Get fresh fuel for any gas-powered equipment.

oSend winter equipment for servicing or purchase replacements.

oPurchase plant- and pet-safe deicing material.

oClean containers, window boxes and other planting containers as you empty them at the end of the season. Store them out of the weather to limit cracking damage.

oPrepare summer equipment for storage.

oReplace worn or broken tools. Clean, sharpen and oil hand tools.

oAvoid pruning anything that can't be reached from the ground. Never prune branches too heavy for you to handle. Hire a certified and insured tree pruner for high pruning or heavy branches or for any work around power lines.

oCheck for ticks after every outing. Use an insect repellent containing Deet on the skin. Apply a repellent with permethrin to clothing. Wear light-colored clothing, long sleeves, hats and long pants when working in grassy areas or under overhanging branches.

oStay hydrated. Drink plenty of water or other non-caffeinated or nonalcoholic beverages.

oApply sunscreen, wear hats and limit exposure to sun. Avoid peak exposure hours—11 a.m. to 2 p.m.

oAlways wear gloves to protect hands. Use eye protection when cutting or chopping and appropriate ear protection when using any loud power tools.

Watch the video: Surviving Your First Winter With Houseplants. Indoor Plants Winter Care Tips

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