Plants that frost in winter with words "how to keep plants warm in winter"

Building your own garden can be a lot of fun. But a cold winter can be a terrible disaster for the expectant growers. The question is, how do you keep your plants warm during the winter, especially the fragile seedlings? It's really not that complicated for plants in pots or grow bags compared to those living in the wild nature. Here are some tips on how to keep your houseplants warm in the winter.

Move Your Plants To A Warmer Place

As winter approaches and temperatures drop, growers need to move their potted plants. This is the most straightforward and easiest way for the entire plant to stay warm and withstand the cold winter months.

Move Outdoor Plants To An Indoor Room 

If you've got a greenhouse, great! Move all of your outside-grown plants into that greenhouse. If not, try moving your outdoor plants into your room, preferably in the sunniest room in your house. Being away from howling cold wind and possible winter disasters like Hailstones, your plants will have a stable environment to keep going.

Move Indoor Plants To The Warmest Place

If you're already growing in a room, place your houseplants near the warmest part of the room, such as a fireplace, radiator, or other areas you use for heat.

With a good budget, investing in a grow tent is a perfect solution because it can maintain warmth and protect against frost as the grow tent was built and enclosed with multiple layers. Because of the sealed structure of grow tents, the environment inside and outside the grow tent is completely separated for you to better monitor and manage the temperature and humidity inside, and be free from the extra cleaning work caused by the plants.

A green plant indoors near the sunniest window, fireplace, and near an indoor grow tent

Some growers may wonder: even if I keep the plants indoors, I don't have the extra space to get it somewhere warmer; or I'm growing in a cold garage, which is a grow room I can't move, and it's not in the vicinity of any heat source. What could be done?


Keep Away From The Easy-To-Ignore Cold

Some smallest details can always lead to great cold damage to your plants from unexpected aspects.

Keep Roots Off The Floor! 

The ground temperature can change drastically in winter, even indoors, and that is something growers usually ignore.

To avoid sudden temperature changes to your plant roots, keep them off the floor or metal tables. Try wrapping the pot in insulating material to protect its roots from low temperatures. You can also put a layer of plastic foam under the pots or fabric grow bags.

Rearrange Your Ventilation

Growers always get fresh air directly from nature outside, which is certainly the right and energy-efficient way to provide healthy air and carbon dioxide for your indoor plants. However, this can expose your plants to air temperature imbalances. A better approach is to extend ventilation ducts so that fresh, cool air is in contact with the indoor environment for longer periods of time to soften the shock of the cold outside. If allowed, it will be better to put part of the ventilation ducting in hot water.


Create A "Greenhouse" Environment For Seedlings And Young Plants

Seedlings in a germination box and with plastic rapped like a small greenhousse

With a grow room or a grow tent, attentive growers could use a blower or inline fan to deliver moist and warm air into the enclosed growing space. This can be especially effective when used in conjunction with an existing heating system in an enclosed room (like an unheated garage). However, be aware that excessively moist air may affect the relative humidity and thus bring unwanted disease crises to your indoor growing.

An indoor grow tent is always a good investment in being a “greenhouse”. But if you’re not prepared to use a grow tent, there are other ways to create a "greenhouse" environment for your young seedlings and plants. One method involves covering seedlings or plants with plastic domes that are held up over the plant by hoops or supports. The domes trap heat, keeping your indoor garden warm while shielding it from cold drafts. Some people will even set up special enclosures made out of glass or plastic called cloches—these are like little greenhouses that sit on top of pots and bags guarding plants in wintertime.


Run Grow Lights At Night

If you have grow lights and a timer, use the grow light at night to leverage its working heat. Although LED grow lights generate little heat, they can still collect some warmth to the plants without stressing or drying them out. This added warmth will help defend against nighttime cold spells.

Usually, the late-night and early-morning electricity charge rates are the cheapest, and using grow lights during these hours can also help you save a considerable amount of money on your electricity bill. However, it should be noted that this method is only applicable to growers with enclosed growing areas, as the heat from the grow lights can easily be dispersed by the cold outside.


To Use Seedling Heat Mats "Right"

The right way to use a seedling heat mat for germination and cloning is with a sensor probe

A seedling heat mat (or called propagation mat) is a thin, flexible panel that produces heat, typically used for starting seeds and rooting cuttings in order to avoid possible "cold root syndrome". Some growers are skeptical of its effectiveness in warming plant roots because it is a rollable flat sheet that produces little and mild warmth. Well, you may be using it in the wrong way.

For indoor plants using fabric grow bags, the proper way to use a seedling heat mat is to place a tower between the fabric bag and the heat mat to make the warmth gentler and last longer. If the grow bag is quite large, then wrapping it with the seedling heat mat is a better way to go. By warming up the soil, the roots will receive stable and consistent warmth throughout the winter.

For potted plants, we need “thermal conductive media”. Place the propagation mat on an insulated surface such as styrofoam sheets, a thick stack of newspapers, a cardboard tray (wrapped in a plastic garbage bag to keep out water), or an overturned plastic tray to generate heat and conduct it evenly to the plants.

For indoor growers, a seedling heat mat is a perfect investment to help plants survive the cold winter, especially for those who need to germinate seeds, grow seedlings and clone mother plants. The constant and steady warmth from a seedling heat mat will do wonders for the health and strength of young plants.


Just Invest In A Heater

If you have too many plants or too much growing space to care for, just invest in a heater. You have a heater, you have a warm environment, and your plant roots will be happy. However, there are many limitations to the use of heaters.

Never place the heater directly on your plants. When you need the heater to achieve the optimum ambient temperature, the heater is necessarily set higher than that. At this point, if you place your plant near the heater, it will likely get burned. If you only need the heater to warm your environment thus to keep the plant from the cold, then set the temperature no higher than 75°F (23°C).

Pay attention to ventilation, especially in confined environments. When air is repeatedly heated without being replenished with fresh air, plants are stressed-that is, prompted by the harsh environment from within-and thus show a tendency to grow worse.



Hopefully, this article has given you some great ideas for how to keep your indoor plants warm in winter. In fact, the investment in some necessary winterizing equipment will spare you a lot of unnecessary losses if your indoor plants are very sensitive to the environment. A grow tent, a seedling heat, or a heater will save you from chill worries and promise bountiful results.


Warm Giveaway

mars hydro seedling heat mat giveaway

In order to help growers easily keep their indoor plants warm over the winter, Mars Hydro decided to select two lucky growers and send them seedling heat mats.

  1. Participation Rules: Tell us about “How You Help Tour Plants Get Through The Winter” in the comments section of the blog.
  2. Two winners will receive one of the prizes at random:


           *MARS HYDRO SEEDLING HEAT MAT 48''X20.75''(2 PACK)

  1. Ends Time:November.11th



Congratulations to "Burt Macklin" and "Joe Fleming" on winning the two prizes! Our staff has contacted you via email, please check out your email box to claim your prize and get back to us!

how to keep plants warm winner 1how to keep plants warm in winter winner 1

how to keep plants warm winner 2how to keep plants warm in winter winner 2

Good luck and wish everyone a warm and hopeful winter!