Guest Contributor: Cassey Anderson, Horticulture Agent, Colorado State University Extension
Some gardeners may see the first freeze of the season as a sign of relief, the ability to change gears and work on other projects, take a breath, or prep the garden for next season. Others may not want to give up the opportunity for continued production. If you fall into the second category (or perhaps your tomato plant JUST now started to give you some amazing tomatoes) then this article may have some suggestions that allow you to continue growing despite freezing temperatures outside.
What to Think About Before You Bring Plants Inside
Some elements to consider before bringing your entire vegetable garden inside:
Light
Most vegetables thrive with at least 12 hours of solid sunlight a day. Now my house is pretty typical and gets at maximum 6-7 hours of direct sunlight if positioning plants very carefully. This means that for optimal produce you will need to provide supplemental light. There are lots of options for inexpensive grow lights available (and you can get as technical as you'd like in searching them up) but if you look for a light that provides a full spectrum of light that should be sufficient to keep your plants going.
Do note that lights, to get full benefit, do need to be much closer to the plant that you might initially think so plan carefully, but also avoid plants touching the light as that can burn the plant.
Temperature
While many plants love high temperatures, most do not tolerate very cold temperatures, so ensure you're putting your plants in a part of your home where they will be as comfortable as you. If you're inclined to keep your home very cool (50s or 60s F in the winter) this could lead to some of your warm season crops growing either very slowly or going "dormant" during the cool period. If that is the case, be sure to change how you water so you don't drown your plants!
Water Management
Watering outside plants has its own stressors, but when walls, floors, and lower-level spaces come into the picture you want to ensure your plants are getting the water they need, and that your house isn't. Typically putting some type of water catching trough under plant pots should be sufficient. Remember, after watering, empty the water catcher so you don't develop standing water which can rot plant roots.
Space
While many gardeners may tolerate being shoulder to shoulder with plants throughout the house there may be other members of the household who don't appreciate having to share every square foot with a plant of some kind, so ensure that you only bring in the plants you have reasonable space to accommodate. If your plants are extremely large (as some tomatoes are wont to do) you may need to also determine a way to support them during transport and while inside.
The Easy Ones
Potted Tomatoes and Peppers
In their native habitat tomatoes and peppers are perennials and so, with care, can be brought inside and overwintered. If provided sufficient light, water, and nutrients, you can continue to get production. If light is not sufficient the plant may remain alive but go dormant until conditions improve. I have a pepper that is about to go into its fourth winter inside, it doesn't flower or fruit, but it stays just alive enough to bring back out in spring. If allowing the plant to become dormant you may want to reduce watering as a dormant plant uses far less resources than one that is actively growing.
Potted Herbs
Also a fairly easy option, some potted herbs may tolerate a sunny windowsill if you don't want a lot of growth, but as with the peppers and tomatoes, if you want to be able to harvest regularly it's important to nail in the light and water ratios. Some herbs, such as rosemary, are particular about how wet the soil is, so be sure to watch how you're caring for the plants. When growing herbs indoors it is often better to grow in separate containers as individual water needs may vary. The three-in-one rosemary, sage, oregano combination looks adorable at the store but can be challenging to keep alive indoors.
Potted Greens
If you're a container gardener and you have leafy greens such as lettuce, spinach, kale, arugula etc. then you can easily bring them inside and keep them growing. Leafy greens can grow with lower light levels than peppers/tomatoes or herbs, so you may be able to get a few harvests without supplemental light, but more light will lead to more growth.
For the More Adventurous Gardener
If you've done the above plants and found them easy to keep alive there are some options that will be harder to manage:
Transplants
When going from an in-ground or raised bed into a container you're likely to experience transplant shock, so plan accordingly. Select plants that aren't enormous or at least prune back the top of the plant substantially to reduce water loss through transpiration. It could be good to transplant a few weeks before you anticipate your first frost date so you can baby the fresh transplant before bringing it indoors. Transplanting is likely to be more helpful for plants that produce continuously like peppers, tomatoes etc. It is unlikely to work with plants such as beans, cucumbers, melons etc. as those varieties do not tend to transplant well.
Starting Indoors for Winter Growing
If you tried to bring some of your vegetable garden indoors but perhaps it didn't go well and you still want to grow indoor plants perhaps consider starting some new seed in a sterile potting soil and providing good lighting. You can grow leafy greens very easily and some herbs can be quite easy to get started and harvest reliably as well. Ensuring a good balance of light and water is important. Most vegetable plants do not like having constantly wet roots, but also will not tolerate the soil drying out completely (especially if you want good flavors).
One More Thing Before You Bring Plants Inside
Note: when bringing potted plants inside it's important to check for any dirt, debris, insects or other pests on the plants, pots, or in the soil. If you find anything problematic that cannot be cleaned off then it may be wise to avoid future stress by not bringing that particular plant/pot inside.
Hopefully these have been some helpful hints for extending your growing season by bringing the garden inside. As always, reach out to your local Extension office for additional help or to answer other questions you may have.
As always, reach out to your local Extension office for further information if you have any questions.
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