It’s time to move many of your outdoor plants indoors when frost threatens. There are many bulbs, annuals, herbs, and tropical plants that will only survive the winter indoors. We’ve got advice on how to winterize your plants and pots this fall in addition to which plants to bring indoors.
When to Bring Plants Inside?
Neither true annuals nor plants that we grow as annuals (which in southern regions are considered tender perennials) can withstand temperatures below 45 degrees fahrenheit. The plants are not going away forever, however! Plants that need to dormancy in winter can also be brought in as annuals, even tender species. Ideally, these should be brought inside before nighttime temperatures drop below 45°F (7°C). Once the nighttime temperatures reach about 50°F (10°C) in the fall, start bringing your plants inside for the winter.
The majority of tropical plants suffer damage at temperatures below 40°F (4°C), a few even at temperatures below 50°. In order to acclimatize them, you’ll need to take action well in advance of a possible freezing event.
Where to Put Plants?
In spite of the fact that we have a greenhouse attached to our home as well as bright sunlight and temperatures that don’t usually fall below 45°, I still have trouble fitting everything into it. It’s fortunate for me that most of these plants would undergo a dry period in their native lands and don’t mind being pushed under a bench for a rest.
Think about designing a shelf or area to group all the plants that need high humidity together if you are not lucky enough to have a greenhouse. It may help to mist your indoor plants, but this only lasts for a short while. You may want to consider placing a pebble tray under your plants as a long-term solution. The trays should be lined with waterproof material, a layer of gravel should be added, and the pots should be placed on top. Maintain a moist gravel surface. You might want to install some ceiling hooks if you have hanging plants. Also, make sure that your windows are clean inside and out so that your plants will receive adequate light this winter.
Which Plants to Bring Inside?
You may have to make some tough choices about what’s worth bringing inside. How many of your plants are keepsakes? When it comes to replacing them, which ones are the most expensive? Additionally, you should only keep healthy plants and not those with diseases or pest issues. It’s important to consider your indoor lighting, too. Even a west or south-facing area with glass has a winter light intensity no greater than a shady area in the summer.
There are two groups of plants that you can bring inside:
- Plants that require a period of dormancy during the winter.
- Plants that can continue to grow throughout the winter.
Plants Requiring Winter Dormancy
A period of “dormancy” is necessary for some bulbs when they are tender in a cool environment well above freezing. Many of these bulbs are expensive and are worth overwintering. Here are some tender bulb examples:
- Calla lilies
- Elephant ears
- Tuber roses
If you have tender bulbs in pots, stop watering them, cut off their dying foliage, and store them somewhere dark and cool. Make sure the soil is moist at all times.
If the bulbs are in the ground, dig them up and trim their foliage. The bulb should be brushed as much as possible to remove soil. Place them somewhere warm and dry for 7 to 14 days for them to dry. It removes excess moisture from the air. Separate them using shredded newspaper or dry peat moss, and pack the pots loosely in a cardboard box or open container. You should retreat into a dark, cold place. Put them up about a month before you intend to plant them outside so they have a head start on the season.
Plants That Keep Growing in Winter
I enjoy growing annuals, herbs, and tropical plants through the winter, and I even get a few blooms from time to time. This plant needs exposure to the sun, but it is not too bothered by cool temperatures.
- Fibrous begonia
- Geranium (if given plenty of light)
If you want the plant to thrive fully indoors, it’s important to acclimate it gradually to lower lighting levels. Place a plant that’s receiving full sun outside in a shadier spot. If your plants are accustomed to bright light, try to provide them with similar light inside, such as a south window or under a plant light set to 16 hours each day. During this time, they will adjust to the new conditions and will recover. Don’t be alarmed by leaf drop.
You should also prune your plants before bringing them into the house if they need shrinking temporarily.
In order to prevent bugs from eating the fuchsia plants, I cut off their leaves and water just enough to keep the roots alive. When the time comes for them to return to the outside, they will be in bud and will begin growing again in the spring.
In winter, we keep the geraniums blooming all year, but if you do not have a sunny spot for them, you can let them go dormant by cutting back by about half, covering the top with a bag, and watering only when dried out. Many people even remove the bare-root plants from their pots and hang them upside-down in a dark, cool place, spraying with water periodically to keep them from drying out. Plants should be repotted after soaking their roots for several hours in the spring to rehydrate them.
Get Rid of Pests!
Whenever I water the leaves, I make sure I shake the leaves vigorously and wash the pots thoroughly to ensure I don’t bring in any unwanted guests, including bugs, slugs, cocoons, and egg masses.
When these pests are observed, treat them with an insecticidal soap or other insecticide labeled for these pests. I use a soapy spray made from 1 teaspoon of non-detergent soap to spray down all the leaves mixed with water in a 1 qt. spray bottle. The life cycle of spider mites is seven to ten days, thus weekly spraying typically halts their growth. Whenever I notice whiteflies, I put up sticky cards in yellow to catch them. Remember to spray underneath the container’s lip as well as at the bottom of the container, where bugs can hide.
Indoor Plant Care Tips
Overwatering is not a good idea! Despite the fact that indoor plants do not require much water in winter, this is the most common cause of death for them. The top 1/2 inch of soil should be completely dry before you water it again. Water only when you are sure. When the soil has been dry for several days, water succulents even less often. It is best to avoid watering plants in the rain or cloudy weather, since the plants will not get sufficient light to dry out.
Due to the lower light intensity levels during the winter, plants require little to no fertilizer. The spring is the best time to fertilize your plants.
It will save you a significant amount of money if you overwinter some of your tropical plants. Plants you don’t have room for in your window should be offered to a gardening friend.
I also take cuttings of many of my favorites, like Iris, Begonia, Geraniums, Impatiens, and Coleus just to be on the safe side. They will all root easily in water and make attractive houseplants.
You can create more plants inexpensively and easily with cuttings if you don’t have enough room for pots over the winter.
To take a cutting:
- Trim the shoots back about 2 to 3 inches just below the leaf node if they are healthy. Leaves and flower buds on the lower part of the plant should be removed.
- Put the cutting in a moist rooting medium, such as coarse sand, vermiculite, or sterile potting mix (which usually contains peat and perlite). Make sure at least one leaf node is below the surface of the medium. If you plan to plant a cutting outdoors, consider dipping it in rooting hormone prior to planting. Success may be more likely with it.
- The cutting should be placed in bright, indirect light. Be sure to maintain an even level of moisture. Adding a plastic lid or clear bag to the container will help reduce the overall moisture loss.
The rooting process typically takes between one and three weeks, depending on the species. As soon as the roots are well developed, you can transplant them into a larger pot.
Moving Plants Back Outside in the Spring
During spring, your plants will start sending up new growth, and you can move those pots back into the sunlight and continue watering them. When they need a new pot, provide fresh soil.
Removing them from the ground after the last frost is a safe practice.
A Few More Winterizing Tips
- Containers made of plastic or wood can be left outdoors over the winter. Terracotta clay containers, however, are susceptible to cracking and should be stored inside.
- If the temperature drops below freezing (32°F / 0°C), disconnect any outdoor faucets that are connected to garden hoses. To prevent insects and debris from entering the water, screw the hose ends together after draining the water completely. Afterward, you should store them under your deck or in your garage.
- It is expensive to buy good tools! Take the time to properly take care of them. Make sure tools are clean and sharpened with a wire brush. For metal surfaces, apply WD-40, or an oil-based product. Apply a light coating of wood preserver to wooden handles and clean with an all-purpose cleaner.