When you’re tired of waiting for seeds to germinate in your greenhouse or indoors, you need to get a seedling heat mat.
A heat mat for seedlings warms the soil in starter trays to the perfect temperature that triggers seeds to germinate, so you can grow strong, healthy plants ready for spring transplanting.
Inside this buying guide, you’ll get reviews of 5 of the best seedling heat mats available and find answers to common questions about their use.
What I Look For:
| Thermostat | To Help Control Temperatures |
| UL Listed / MET Certified | For Electrical Safety |
| Instructions | To Help With Setup |
| Water Resistance | To Protect From Spills |
Top 5 Best Seedling Heat Mats
Best Overall
VIVOSUN Seedling Heat Mat and Digital Thermostat Combo Set
Reasons To Buy
- Kit includes mat and thermostat
- Maintains consistent temperatures from 68°-108°F (20°-42°C)
- Uses FAR Infrared heating technology with double insulation
Reasons To Avoid
- The high-temperature range may scorch surfaces without protection
- Some reports of faulty thermostats that needed replacement
The VIVOSUN Seedling Heat Mat brings a simple-to-use yet professional-quality gardening tool to your home or greenhouse.
The mat exceeds standards for safety and can handle the demands of cleaning and storage without damage.
The large heat mat works best for serious growers who need to warm several seed-germination or plant-propagation trays.
With a controller and sensor probe, you can ensure accurate readings through a wide range of temperatures.
The VIVOSUN 48″ x 20.75″ Seedling Heat Mat is a great size for larger germination trays or several smaller ones, so you don’t have to plug in a multitude of mats. The wide temperature range and inclusion of the thermostat make this kit perfect to handle all types of seed-starting needs.
Best For One Standard Seed Tray
Seedfactor Seedling Heat Mat
Reasons To Buy
- Accurate temperature settings and consistent heat delivery
- Extra-long thermostat sensor cord
- Temperate range of 50°-108°F (10°-42°C)
Reasons To Avoid
- The dimension will only fit one standard size seed tray
- The sensor doesn’t read well when the soil isn’t moist
The Seedfactor Seedling Heat Mat is MET certified and offers an impressive temperature range for seed germination, so even growers in frigid climates can benefit from its use.
The easy-to-read LED thermostat and sensor combination is 100% accurate, preventing seedling loss due to faulty readings. Using the mat can increase germination rates by up to 40%, making it perfect for beginner gardeners starting a small number of seedlings.
The mat is waterproof and rugged, with updates on the heating wire and insulation layering, so you can rely on it to work season after season.
The Seedfactor Seedling Heat Mat delivers accurate readings and a wide temperature range so you can provide seeds the optimum soil temp necessary for the best germination rates.
Best Budget Pick
Hydrofarm Jump Start Seedling Heat Mat
Reasons To Buy
- Provides full and even mat warming 10°-20˚F (6°-11°C) over ambient room temperature
- The only fully UL-listed heat mat on the market
- Convenient 6-foot power cord
Reasons To Avoid
- Small size fits one standard seedling tray
- No display to know the actual temperature
The Hydrofarm Jump Start Seedling Heat Mat is a small mat that features the best heating surface uniformity on the market, which maintains reliable warmth across the whole pad so more of your seeds will sprout.
The affordable price includes the UL listing for safety, and the entire mat surface is vacuum-sealed, as opposed to only the outer seams of other brands.
The mat is ideal for greenhouses and growing spaces that only need a small boost in heat to trigger seed germination.
The Hydrofarm Jump Start Seed Starting Heat Mat put in the extra effort to produce a superior product with double insulation, complete surface vacuum sealing, and instructions right on the mat for easy reference.
Best For Beginners
RIOGOO Seedling Heat Mat And Thermostat Controller
Reasons To Buy
- Creates a stable temperature between 68°-108°F (20°-42° C)
- Waterproof mat with an easy-clean surface
- Simple 3-button thermostat controller
Reasons To Avoid
- Small mat size limits how many seeds you can germinate
- May need to place the probe in cold water to trigger thermostat operation
The RIOGOO Seedling Heat Mat with Thermostat Controller is a complete kit to keep your seedling trays at the temperature you choose with straightforward settings to avoid mistakes.
The heat mat is IP68 Waterproof and can maintain a consistent heat level to ensure better flower and vegetable seed germination rates.
The controller has a large digital readout to see the soil temperature at a glance easily. The sensor works equally well in both warm and cool soil.
The mat’s size is ideal for gardeners with limited space who want to start seeds indoors, so their spring garden gets off to a great start.
The RIOGOO Seedling Heat Mat with Thermostat kit saves money and second-guessing if you’re keeping the soil at the right temperature. The quality components ensure flawless operation even for beginners, so more of your seeds can germinate.
Best For Range Of Temperature Control
iPower Warm Hydroponic Seedling Heat Mat And Digital Thermostat Control
Reasons To Buy
- Offers widest thermostat setting of 40°-108°F (5°-42°C)
- Multi-layer construction improves insulation and durability
- Includes controller with LED display and clear instructions for use
Reasons To Avoid
- Heat across the mat isn’t always even to the edges
- It may take a few tries to get the sensor and thermostat configuration working correctly
The iPower Seedling Heat Mat Combo Set features the most comprehensive temperature range for customizing all your germination needs using only one mat.
Stick the sensor probe into your seedling soil, set the temperature on the user-friendly thermostat controller, and watch your seeds begin to sprout under warm soil conditions.
The LED display is bright and clear to monitor heat levels from a distance. The construction is durable and long-lasting, which increases overall value.
The iPower Hydroponic Seedling Heat Mat and Digital Thermostat Control Combo offers more range to keep your seedling trays at the best temperature for sprouting.
Seedling Heat Mat Buying Guide
Buying the best seedling heat mat will help you germinate more seeds so you can get a jump-start on your gardening season.
To help you understand just what you need, I put all the details about heat mats for seedlings below.
Do Seedlings Need A Heat Mat?
No, many gardeners start seeds without a heat mat, so it’s not a requirement. But, heat mats do help you regulate sprouting schedules more effectively as seeds need specific soil temperatures to germinate.
Without a heat mat, your seeds will rely solely on the ambient air temperature of your growing room to trigger sprouting. With a seedling heat mat, you can force seeds to germinate at will by bringing the soil to the right temperature for that plant without altering the temperature of the entire space.
How Does A Seedling Heat Mat Work?
A seedling heat mat is similar to a traditional heat pad people use to soothe an aching back.
The mat is typically a thick plastic material with heating elements running through it that warm up after you plug it into an electrical outlet. You place the seed tray on top, and the mat warms the soil.
The temperature of the heat mat isn’t intense. Its intent is to warm the soil in the seedlings’ trays to around 10-20°F (6-11°C) over the ambient air temperature, so the seeds germinate.
For heat mats with a thermostat, you place the probe into the soil, set the controller to the temperature you desire, and the heat will remain consistent as you wait for your seeds to sprout.
Seedling Heat Mat Thermostats And Temperatures
Many heat mats for germinating seeds come with a thermostat with a digital display for easy monitoring of temperature settings.
A mat without a thermostat sensor and digital readout makes it hard to pinpoint the soil’s warmth. Without a soil thermometer, you could potentially under or overheat the seeds and see low germination rates.
Most seeds need soil temperatures to be between 70-90°F for sprouting to occur. Cool-weather vegetable seeds may quickly germinate at lower temps, so the need for a heat mat may not be necessary if your greenhouse or growing area is above 55°F.
You need to understand the needs of each specific variety of plant you are trying to grow so that you can set the heat mat to the best temperature for seed germination.
What Size Seedling Heating Mat Should You Buy?
The size and amount of seedling trays you plan to grow will determine the size of the seedling heat mats you buy.
Here is a breakdown of heat mat sizing vs. how many standard seedling trays they will fit:
- 10″ x 20″ mat will fit one tray
- 20″ x 20″ mat will fit 2 trays side by side
- 12″ x 48″ mat will fit 2 trays
- 20″ x 48″ mat will fit 4 trays
If you have a variety of seeds that may germinate at different rates, use smaller trays or individual pots so you can remove the plants that have sprouted from the mat and leave the rest.
Leaving seedlings on the heat mat for a few days while waiting for the remaining seeds in the tray to sprout shouldn’t be harmful to their overall growth.
Seedling Heat Mat FAQs
Are Seedling Heat Mats Safe?
A seedling heat mat is safe as long as you follow standard precautionary procedures as you would with any other electrical appliance. Heat mats can overheat, so using one with MET certification, a thermostat, and a GFCI plug is crucial to prevent scorching table surfaces or from starting a fire. A mat with auto-shutdown when it senses overheating is another option that increases safety. Use caution when watering to avoid the heat mat plug and wiring from coming in contact with water, which can cause electrocution.
What Surface Should You Put A Seedling Heat Mat On?
The best surface to place a seedling heat mat is wood with a buffer layer of cardboard or a piece of foam insulation for the mat to sit on. Granite, marble, or cement surfaces also work but are naturally cooler, so the mat must work harder to maintain the correct temperature for seed germination. Once your heat mat is in place, buffer your seedling pots or trays. Place one or two layers of empty plastic plant trays between the heat mat and your seedlings to stop intense heat from harming delicate roots.
When To Remove Seedlings From Heat Mat?
You must remove seedlings from the heat mat as soon as your seeds have sprouted. At this stage, heat will only cause the seeds to grow faster, which can leave your plants leggy and weak. Excessive heat may even kill off the seedlings or encourage soil fungi to grow. Not all seeds will sprout at the same time, so watch daily for new growth and remove those seedlings off the heat mat and place them elsewhere in the room or greenhouse where they will receive proper light and ambient temperature to continue growing.
In Summary
Soil temperature is key to the success of seed germination, and a seedling heat mat is the best way to achieve a consistent heat that encourages seeds to sprout.
For those on a budget, the Hydrofarm Jump Start Heat Mat gets high marks for raising the soil in seedling trays a safe amount to speed up germination without needing a thermostat.
For gardeners who want the best heat mat for starting seeds, the VIVOSUN Seedling Heat Mat with Digital Thermostat combines reliable functions with a larger mat size so you can germinate multiple seed trays at one time.
When you want to start your spring garden with strong flower and vegetable plants that will bloom or fruit faster, using a seedling heat mat is a gardener’s best-kept secret for success!
