How to Use a Heat Mat for Plants to Grow Seedlings Faster - Backyard Boss
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How to Use a Heat Mat for Plants to Grow Seedlings Faster

As I’m preparing my patio container garden this spring, I’ve been thinking about ways to grow seedlings easier and better than I have in the past years. One of the ideas I’ve found that’s been helpful is using a heat mat for plants.

These devices help promote growth, faster germination, and generally, an easier start to gardening season, especially for beginners and folks who live in cooler climates.

What Is a Heat Mat?

If you’re not familiar with the idea of using a heating pad for plants, then let me introduce you to this great choice.

So, seeds germinate at temperatures between 65 and 90 degrees Fahrenheit, in most circumstances. That’s part of why spring (or summer in some regions) has to hit before planting seeds outdoors is a good idea. For those of us who don’t live in warm climates (I’m looking at you, Chicago, with your threats of snow in May!), this may not be so great for producing a garden in the summer.

A heat mat is basically a gentle heating pad like you might use for relaxing a muscle after injury, except that it’s designed to be used for lying beneath a bed of seedling starter pots to help the seeds hit that germination temperature earlier than they would outside.

Is a Heat Mat Necessary for Germinating Seedlings?

close up of durian seedling in soil

Heat pads for plants use little electricity, keep plants warm overnight, and many come with thermostats so that you can easily adjust the temperature. So, though technically the answer is no, you don’t require a heating pad for seed germination, they are certainly helpful in many ways.

Heating pads are especially useful with the idea that moist soil is cooler than dry soil, naturally, which is counterintuitive for germinating those seedlings, since they need plenty of water to grow.

Most instructions for germinating plants suggest that natural warmth from the sun will help seeds germinate faster – and it will. But sunny windows or south-facing windows may not always be an option, either, like in my household. We have no south-facing windows, and my cat thinks all planters are for rolling around or making mud in.

Do Heat Mats Help Plants Grow?

Heat mats are not guaranteed to grow plants, but if you have healthy seeds, keep the soil moist, and include some natural or artificial light, heat mats may improve the growth of seedlings or speed up germination.

How to Use a Heat Mat to Germinate Seeds

Using a heat mat for your plants is pretty easy. A few simple steps and tricks will make them efficient and effective and nearly guarantee success every time.

  1. Purchase a high-quality heat mat. For best results, choose one with an adjustable thermostat so that you can better accommodate specific plant types with their ideal germination temperature.
  2. Study temperatures required for your seeds to germinate and plant seeds according to instructions in seed starting pots. For best results, use seeds that germinate at the same temperature as each other.
  3. Place the heat mat under seed starting flats, pots, or cell trays.
  4. Keep the soil moist and protected from digging pets!
  5. Give the mats a few days to work their magic. It usually takes a few to several days to warm the soil (especially in deep or large pots).
  6. Throughout, check the soil temperature to make sure the heat mat is working properly. Even those with thermostats may be off a little and need adjustment, depending on pot size, soil depth, etc.

seedling tray with human hand visibly cleaning a seedling

How Long Should I Keep Seeds on a Heat Mat?

Once the seeds have sprouted, remove the pots/trays from the heat mat and move under a bright or grow light. If the room is cool, however, instead raise the planters above the heat mat to avoid direct heat while still keeping the soil warmer.

Heating Mats for Quick, Easy Results

Seedling heat mats are a great tool that can help gardeners in many circumstances improve their experience and speed their seed germination. Just remember to keep the soil moist and remove the seedlings from the mat once they’ve sprouted and set them under a bright grow light for best results. Heating pads for seedlings are helpful, but they’re not the end-all of care.