Whether you’re starting seeds off in the cold, winter months, encouraging cuttings to root or raising tender plants originally from warmer climates, a constant heat source will help create the best conditions to nurture them. Heated propagators are an ideal accessory which, depending on the type you choose, either offers a consistent, ambient temperature or can be set at a particular temperature to suit your needs.
Because of our cooler temperatures, warmer climate plants like tomatoes, aubergines, chilli and bell peppers and squashes need a long growing season to give them time to grow, flower, produce fruit and for the fruit to ripen. Germinating them indoors in a heated propagator early in the year, when outside it would be much too cold for them to grow, ensures they get the long growing season they need. But even hardier and native plants benefit from being germinated at a constant temperature.
Essentially a watertight plastic tray with a clear lid, heated propagators contain a heating element that keeps the soil at a steady, warm temperature, which encourages root growth in both seeds and cuttings. A basic propagator is pre-set to 15C-21C, the optimum temperature for germination, while more sophisticated models have a soil thermometer and a thermostat to give you greater control depending on what you're growing.
Another option is a heat mat. Simply, a rubber or plastic mat with a heating coil inside to provide bottom heat to seedlings and plants, they're a cheaper way to help increase germination and easy to use- simply lay the mat out flat on a dry, even surface and place your tray of seedlings or pots on top. However, they lack a cover and so are unable to create humid conditions, which is also beneficial when seeds are germinating and the soil needs to stay moist. But they’re great for storage, as they can simply be rolled up and put away when not in use.
Growing other plants? Check out our guides to the best self-watering planters, or the best garden cloches. And if you're growing in a greenhouse, our useful greenhouse accessories article is worth a look.
The best heated propagators and heat mats
Browse our selection of heated propagators, below:
Garland Fab 4 Electric Heated Propagator
The Fab 4 propagator is a great entry-level propagator for new gardeners. It gives a first-time user ease and simplicity without compromising on quality. With four cells, it's great for growing a range of plants for the first time and easily keeping track of what’s what.
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Buy Garland Fab 4 Electric Heated Propagator from Amazon
Garland Super7 Electric Heated Propagator
This heated propagator from Garland is built for propagating in bulk and can grow seven different cells of plants at once. If you’re after a bumper harvest, this lengthy propagator can give a host of plants a head-start.
Buy Garland Super7 Electric Heated Propagator from Thompson & Morgan
Harrod Horticultural Electric Starter Propagator
If you’re keeping a close eye on your energy bill, this electric propagator from Harrod Horticultural is a good option, with the 10 watt heated base using only a sixth of the power of a normal lightbulb. The lid has an adjustable vent which lets you have control over the humidity levels in the propagator depending on what you’re growing.
Buy the Electric Starter Propagator from Harrod Horticulture
Selections Jumbo Windowsill Heated Plant Propagator
This heated propagator is designed to fit on a windowsill, and has a single deep tray that can either be filled directly with soil or pots, which is a useful feature when you’re growing your own. A thermostat control maintains heat at 21°C/70°F, while two vents in the clear lid regulate humidity.
Buy the Selections Jumbo Windowsill Heated Plant Propagator from Amazon
EarlyGrow Heated Electric Shatterproof 2-bay self-watering propagator
Simply plug in and use, this heated propagator produces a steady temperature ranging from 16°C - 21°C (60°F-82°F). Made in the UK with robust and durable shatterproof lids, it’s ideal for novice gardeners as it’s self-watering. The individual bays allow you to grow multiple seeds or cuttings simultaneously without fear of confusion.
Buy the EarlyGrow Heated Electric Shatterproof 2-bay Self-Watering Propagator from Amazon
Sankey 38cm Growarm 100 Propagator Kit
This model comes with 2x21cm seed trays to allow you to grow two types of seed at the same time, a capillary mat to retain water and keep soil moist, as well as an instruction booklet to get you started. The 8 watt heating element keeps the soil warm and is ideal for seeds that benefit from bottom heat.
Buy the Sankey 38cm Growarm 100 Propagator Kit from Amazon
One Top Electric Propagator
This small propagator is a great choice if you’re strapped for space, or just want to grow a few chillies on the windowsill. Using even less energy than it takes to power a light bulb, seedlings will benefit from the constant, extra warmth. The vent is a useful feature, which helps control humidity levels, and though its footprint is small, its clearance is 12cm, which is plenty of room for young plants to get started.
Buy the Garland One Top Electric Propagator from Robert Dyas
Big 3 Automatic Temperature Control Electric Propagator
For a truly bumper season’s growth, look no further than the Garland Big 3. This monster propagator holds three 37.5cm by 23cm trays at once, so you can give kale, tomatoes, sweet peas and chillies a head start at a balmy 19°C, all at the same time.
Buy the Garland Big 3 Automatic Temperature Control Electric Propagator from Marshalls
Large Propagator with Height Extender
This large propagator is perfect if you’re growing large plants of cuttings, and it can also be moved outside to allow seeds access to direct sunlight once the weather warms up a bit. Until we get there though there’s a heated mat which works at 15C above the ambient temperature to help plant germination and growth.
Buy the large propagator with height extender from Marshalls
Riogoo Seedling Heat Mat and Thermostat
This heat mat has a thermostat sensor probe, which helps maintains a stable temperature between 20°C - 42°C (68°F-107°F), and features a digital keypad so it's easy to operate. It comes with a one year warranty.
Buy the Riogoo Seedling Heat Mat and Thermostat from Amazon
ROOT!T Heat Mat
Provide bottom heat to seed trays and pots to help speed up germination and help cuttings to take root. Hard-wearing and easy to use, the mat can be wiped-clean and rolled up after use. It comes with a thermostat for complete temperature control and can be used directly on staging or a table.
Buy ROOT!T heat mats from Marshalls
Consider the following when shopping for a propagator:
- Space - Unless you have a greenhouse with a power source, most of us will use a heated propagator at home. Position it on a flat surface; a windowsill out of direct sunlight is a good spot to ensure seedlings don't scorch on sunny days.
- Size - Make sure the dimensions of the propagator are right for your needs. If you’re planning to grow on tender plants you’ll need a taller propagator than if you're germinating seedlings.
- Features - For most projects, a basic heated propagator, with a watertight tray and a shatterproof lid with ventilation is fine. However, if you’ve the budget to spare, look for self-watering propagators or those with lights to further help propagation.
To get the most out of your heated propagator, ensure trays are clean and plant your seeds in damp compost. Place the propagator somewhere light and well-aired and switch it on. Keep an eye on your germinating plants and if excessive condensation forms on the inside of the lid, open the ventilating holes to regulate the temperature a little.
A non-electric propagator is simply a seed or modular tray with a transparent lid that aims to provide seeds and young plants with a consistent growing environment. The lid helps to increase the humidity within as well as generate and trap warmth, particularly if placed in a sunny spot. Some have ventilation in the lid and may even have watering spots so you can water without removing the lid and splashing plants. Lids can also be purchased separately so you can add them to your seed trays as you need them.
Non-electric propagators are a lot cheaper than a heated propagator, but without the extra, regulated warmth and bottom heat that you get in a heated propagator, growth will be slower and less consistent.
This Product Guide was last updated in February 2024. We apologise if anything has changed in price or availability.