What is Overwintering and Why Should We Do It?
Overwintering is the process by which you keep plants alive through a season in which they'd otherwise die whether it is due to weather or geographical placement. Gardeners like to overwinter annuals to keep them growing and flowering season after season, but organic food movements are encouraging overwintering fruits and vegetable plants, too.
Overwintering produce plants allows you to get a jumpstart on spring harvests. Lettuces, onions, fruits, and more will be prepared to bear fruit before they typically do. If you're a first time gardener you can try overwintering with floral plants and progress to vegetables and fruits the following season. Let's get started.
Best Plants to Overwinter
You can overwinter fruits, vegetables, and florals. Let's explore which of each category overwinter well:
Overwintering Fruits – Although seasonal fruit plants like strawberries or peaches are not best suited for overwintering methods, there are options that do well in the correct environment. Contained gardens have provided a viable foundation for fruit trees and offer the convenience of moving these overwintering fruit options indoors when necessary. Give the following a try:
- Fig Trees
- Citrus Trees
- Cherry Trees
Overwintering Vegetables – There are a handful of vegetable plants that do well in cooler temperatures and harsher conditions. Hardy vegetable options, like the ones listed below, are great for your first year in overwintering because they are a little more forgiving:
Overwintering Florals – Your home is an easy option for overwintering floral plants, as the environment is easily controlled and small containers can be used to easily move plants to better suit their needs. South facing windows tend to offer proper natural light for the following plants:
How to Plan and Maintain Your Overwintered Plants
There are various methods for overwintering and differ for each plant category.
Fruits – Using containers is the best method for overwintering fruit trees, so start your plants outdoors in contained environments. In preparation for shorter and colder days you can slowly curtail watering and composting in mid-late fall.
Citrus fruit trees will need to be taken indoors before the first frost. Fruits like figs, blueberries, and others of deciduous nature can stay in cooler temperatures until their fruits drop and then be brought inside. Hardy fruits, like apples, can be left outside in a protected area in less harsh winter climates.
Fruit trees can be placed in a cool garage, but near windows, where temperatures do not go below 40 degrees Fahrenheit. If the storage area you choose dips below 40 degrees you can place hay over the soil and wrap the container in burlap to better hold heat. Keep soil moist but not too wet, as this will cause root rot. If you find there is low natural light you can place artificial lamps on the trees to help them get enough light through darker winter months with shorter days.
Take your fruit trees outside after any risk of frost. To better acclimate them to new light levels you can place the contained plants in a shaded area for a few days or you can place them outside for a few hours a day and then bring them back into their overwinter storage. Full sun is welcomed after about a week of reintroduction.
Vegetables – Greenhouses and polytunnels are very effective methods for overwintering vegetables. Both offer a protected and more controlled growing environment for your plants, but greenhouses are more permanent fixtures than polytunnels. A polytunnel is defined as a tunnel made of polyethylene, usually semi-circular, of a square or elongated shape.
Planting overwinter vegetables in late fall allows you to enjoy your harvest before your spring garden produces crops. Begin planting in mid-late fall in your greenhouse or polytunnel.
Using modular trays, sow your seeds according to their packet instructions and apply a layer of compost for added nutrients. Do this about 3 weeks before transplanting to protected outdoor gardens. Keep these trays moist and in proper natural light. Artificial lights are an option, too, if seeds are not getting the appropriate solar attention.
Transplant seeds and sow onion and garlic into the ground in mid-late fall. When planting, be cognizant of whether some plants will need stakes for better growth and plan accordingly. Understanding height differences throughout your greenhouse or polytunnel will allow you to plant your vegetables in the best-suited place for their growing pattern. Add a layer of compost when planting outdoors to protect new seedlings and allow bulbs to acclimate.
Outfit polytunnels with drip hoses that allow you to water plants at a slow rate when necessary and keep your greenhouse equipped with watering cans. Depending on the time of year and how cold temperatures are, you may need to manually water plants with warm water to supply water without it immediately freezing. Soil should be kept moist to encourage the plants, but not too wet that it causes root rot or mold.
The polytunnel or greenhouse will provide protection from wind and elements. Given the environment is controlled, you are able to supply heat if necessary. Consider a small heating element if needed when winter is at its most furious. Artificial lighting can also be helpful in instances where you're growing lettuces and kale. It is important to practice using these assistances with care, as you don't want to supply too much heat or light, or allow these machines to run without supervision.
Florals – Florals tend to be much more temperamental than fruits or vegetables. They also offer benefits to your home when they are populating the indoors. Added oxygen in your home, assistance in regulating humidity, and visual enhancement for your home are all welcomed side effects of overwintering florals.
There are two methods of overwintering florals when using them for decor. The first is to simply move contained floral gardens indoors at the appropriate time and then move back outdoors when allowed.
The second method is to take root cuttings from an outdoor plant and plant them in a container for overwintering. This is beneficial if the origin plant is large and unable to be dug up to move, and it helps protect the plant from overwatering and spreading pests or disease. Additionally, you can take cuttings from the original cutting in mid-winter and continue the process so you have more transplants to move outdoors when warmer temperatures arrive.
If you'd like to overwinter florals to use for next season, there are two methods to do so. You can dig up and store fleshy roots and tender bulbs over winter. You can also force a plant into dormancy to easily protect and store it. To do so, place a potted plant, or with newspaper or burlap wrapped around its root ball, in a cool and dark place for winter. You can check on these dormant plants every few weeks and water as necessary. When the last threat of frost has passed you can move them back outside and plant according to their typical instructions.
Threats To Overwintering - Insects and Diseases
Overwintering offers various benefits, but one of the best is the mitigated risk for insect and disease infestation. There are a few insects to keep an eye out for when overwintering in your polytunnel, greenhouse, or home.
Aphids: a soft bodied insect typically 1/8" in length and green, yellow, orange, gray, black, or white in color. Aphids produce a sticky residue known as honeydew that is noticeable on plants. It can turn black when affected by sooty mold fungus. Leaves can curl and turn yellowish and plant growth may be impacted when an aphid infestation occurs. Using an insecticidal soap like Safer® Brand Insect Killing Soap will kill aphids on contact and diminish the issue.
Spider Mites: a miniature eight-legged arachnid that is red, brown, yellow, or light green in color. Spider mites are able to overwinter in either the adult or egg stage under plant debris or hidden in gardens or lawns. When you take plants inside to overwinter you can invite unwanted spider mites into your home. Yellow spots will appear on the underside of leaves as spider mites suck the juice from plant leaves, or leaves may turn white or yellow with brownish tips. A combination of insecticidal soap and pyrethrin will kill spider mites on contact. Use a product like Safer® Brand EndALL when you see Spider Mites or their eggs.
Thrips: at no more than 1/25" in length, these yellowish, black, or brown bugs emerge from overwintering and lay eggs in the spring. During winter, thrips can be found under plant debris or on the plants you bring indoors to overwinter. Leaves under attack will be mottled and may take on a silver appearance. Use Safer® Brand Insect Killing Soap to kill thrips on contact.
Whiteflies: a very tiny white fly that may rise from a cloud of dust when pestered. Whiteflies suck the juice out of plants, which causes stunted growth and an underdeveloped appearance. Whiteflies can also secrete honeydew which attracts black fungus or sooty mold. Use Safer® Brand Insect Killing Soap on these insects and their eggs when you see them on your plants.
Sooty Mold: black soot that is attracted to honeydew and can be found on twigs, leaves, and branches. Neem oil repellent like Safer® Brand BioNEEM® Insecticide and Repellent is an effective sooty mold remedy.
Root Rot: caused by overwatering or a soil fungus, this disease spreads to healthy roots and kills them by restricting their oxygen. If plants are slowly wilting and leaves turn yellow without visibly apparent insect or disease on the plant, then root rot is probably your issue. Remove plants from soil and carefully wash away dirt from the roots. Using scissors cut away any affected roots. Clean the host pot with a bleach solution and replace the soil and compost used to surround the roots.
Whether you begin your garden overwintering adventures with flowers, fruits, or vegetables, and delve into using polytunnels or greenhouses, now is the time to get started! A little bit of work through the fall and winter months will be greatly appreciated when you have flowers in your home through winter and fresh produce in spring!