Everything to Know about Heat Lamps for Plants

by balconyboss

When colder weather rolls around, getting heat lamps for your plants seems like a good idea. But if you haven’t used them before, there’s a surprising amount to learn about this inconspicuous product.

So, let’s go over everything you need to know about heat lamps for plants. We’ll cover where and when to use them (and when not to), which plants benefit from them, and some beginner’s tips.

What is a Heat Lamp?

A heat lamp for plants is simply one that produces more infrared light than any other wavelength. Infrared is commonly used in heating appliances, and here it heats the light around the bulb, which keeps your plant warm.

Although they’re commonly sold as complete sets, the bulb is the more important part of a heat lamp. In theory, you could use any lamp you wanted, providing you have an infrared bulb fitted. However, it’s generally easier to buy a complete set to save you figuring out the correct bulb.

Heat lamps will come as either LED or incandescent bulbs. There’s not much difference in terms of heat production, although LEDs are more efficient. Incandescent bulbs, though, produce warmer light, which is just more pleasant.

Why Use a Heat Lamp?

You can use heat lamps for plants in winter to keep them at an acceptable temperature. It’s most important for tropical plants for obvious reasons. If you have seasonal plants, particularly outdoor ones, a heat lamp won’t be as important because the plants will benefit from a dormancy period.

Of course, if you have very cold winters and you don’t want your more sensitive plants to die, the easiest solution will be to just bring them indoors. If that isn’t an option, a greenhouse with a heater will actually be better than a heat lamp. An infrared heater will be more energy-efficient than a single infrared lightbulb.

While nothing is stopping you from using a heat lamp indoors, there’s often not much need. If you have central heating in your home, it’ll be enough to keep your plants alive. But you might need a heating lamp for plants if:

  • They have special conditions for flowering
  • Your home is particularly cold
  • The plant can’t tolerate any drop in temperature
  • You’re trying to keep some very sensitive seedlings alive

In most cases, these will be very specialist plants. If so, you probably already know you need a heat lamp. When you start moving into more advanced plants that might need these conditions, make sure you do enough research before buying to know its care routine.

Heat Lamps and USDA Hardiness Zones

When we talk about plants we want to grow outdoors, we use something called the USDA Hardiness Zones. It clarifies where you can and can’t grow a plant based on the ambient outdoor climate.

In theory, a heat lamp for plants could help with this. However, it’s not the most viable option because they’re not very efficient, particularly outdoors. For example, if you have a plant that can’t stand freezing conditions, a single lightbulb isn’t going to do much for it. Again, a greenhouse and heater might be a better option.

You might be able to get away with growing a plant one zone higher than suggested if you use a heat lamp and a very controlled care routine. For example, if a plant maxes out at Zone 5, you could probably keep it alive in Zone 4 with a lamp and pot insulation. That said, once you start getting into the cold northerly zones, a lamp won’t do much.

Pros and Cons of a Heating Lamp for Plants

Let’s go over some of the main pros and cons of heat lamps for plants so you can decide whether they’re the best product for your needs.

Pros

1. Helpful for sensitive plants

Some plants really can’t tolerate changes in temperature, even minor ones. As such, a heat lamp can be a good way of ensuring they stay at the most suitable temperature for continued growth.

2. They’re inexpensive

Heat lamps are generally pretty cheap. In fact, you can cut the price even further by only buying a bulb. Providing you’ve got the correct fitting, you can just pop it into any lamp you have lying around.

3. Give seedlings a boost

If you plan to start a vegetable garden, germinating your seedlings early can be a big help. Most need specific (springtime) conditions to get going, so you can push them into earlier growth with a heat lamp.

Cons

1. Not super efficient

Heat lamps for plants really aren’t the most efficient heating option. As mentioned, they heat the air rather than the plant directly. This means you’ll lose a lot of the heat you need, particularly in colder spaces.

2. Affects humidity

If you grow plants indoors, you probably already battle with the issue of humidity. Unsurprisingly, heating the air around your plant will lower humidity, which will often do more harm than good. The extra heat will also cause the plant to lose more water through evaporation, leading to brown and crispy leaves.

3. Not all plants love extra heat

Despite being more infrared light-focused, shade-loving plants will hate heat lamps. Plants such as pothos, ferns, and lilies will all give you a rough time if you try putting them under a heat lamp.

Heat Lamp for Plants vs. Grow Light

When we start looking at extra equipment for growing plants, it’s easy to question whether you need both a heat lamp and a grow light. After all, heat lamps produce light, so surely it’s enough to keep the plant alive from that perspective, too?

Not necessarily. As mentioned, heat lamps produce infrared light, which, unsurprisingly, is on the red end of the light spectrum. The light plants need to grow is ultraviolet, which is on the blue end of the spectrum. So, in theory, heat lamps and grow lights are actually opposites.

For keeping indoor plants alive over winter, a grow light is infinitely more important. The lack of sunlight in winter is a much bigger consideration than the lack of heat, particularly if your home has central heating. But, if you need both, there are some ways around this.

The first is to buy a balanced lightbulb that offers both infrared and UV light. The best product for this is a reptile lamp because they provide a great balance of both. But, by extension, they might not provide enough of either.

Another option is to switch the heat lamp out for a heating mat. These heat the plants from the bottom, ensuring the roots are at a correct temperature while also preventing the leaves from getting burnt.

Choosing the Right Heating Lamp for Plants

So, when it comes to picking a heating lamp for plants, it’s fair to say that a specifically heat-focused lamp often isn’t the best idea. Instead, here are some suggestions for the sort of things to look for if your plants need some extra warmth.

Best for Indoors Growing: Full-Spectrum Light

Your best choice for indoor plants is a full-spectrum lamp. The one suggested here has a good mix of red and blue light, meaning plants will get just enough heat to keep them going without burning their leaves.

Best for Convenience: Reptile Heat Lamp

If you don’t want to set up a full indoor grow operation, a reptile heat lamp is a good choice. They typically use incandescent bulbs that provide red and blue light. Note, though, that they’re designed for animals so won’t have the correct balance of light spectrums for efficient plant growth.

Best for Seedlings: Heat Mat

A heat mat is better for seedlings because it heats them from below. Germination is triggered in part by ambient temperatures, which, for a seedling, means the soil temperature. As such, heating the soil from below makes much more sense than heating from above.

Best for Outdoors: Patio Heater

For keeping outdoor plants warm, the best choice is a patio heater. It still uses infrared but produces it from a filament rather than a lightbulb. However, you’ll want an incredibly weak heater and to combine it with a greenhouse to keep the heat in.

A better option is to bring any plants that you can indoors and to cover/insulate the pots of any you can’t. Only aim to keep plants outdoors that are suitable for your Hardiness Zone. If you’ve got any houseplants or tropical plants on your patio or balcony, be sure to take them inside long before the winter weather hits.

Final Thoughts on Heat Lamps for Plants

There we have it: everything you need to know about heat lamps for plants. Overall, there are better options than heat lamps for plants in winter, both for indoors and outdoors. With indoor plants, your top priority should always be light over heat.

However, if a heating lamp for plants is still a useful addition to your setup, use the suggestions above to figure out which is the best kind.