"Even the most seasoned gardeners get a thrill from propagating their own plants," says Modern Gardens contributor Geoff Hodge. "The first leaves from newly sown seeds or a cutting starting to root are two joys of gardening. However, many seeds, both flowers and vegetables, need to be sown in a warm environment. And to get the best results, you'll need a propagator." We're taking this one step further to give your outdoor plants some germination determination with the best heated propagators.
"A 'propagator' is one of those gardening terms that covers different items but technically, a propagator is just a clear, see-through cover placed over trays or pots to help maintain a warm and moist environment to encourage growth. Even a sealed plastic bag placed over a pot or tray can be considered a propagator. But shop-bought, proper propagators comprise a rigid base unit or tray with a close-fitting rigid plastic lid," explains Geoff Hodge.
Best heated propagators at a glance:
So why bother to invest more in a heated version? Hodge has the answer: "Heated propagators give you far more flexibility. They produce better results with a wide range of plants, creating a warmer environment for more successful and quicker germination and rooting. Importantly, they produce bottom heat, providing warmth directly to the compost. This is necessary for success; warm compost is more important than warm air." We're taking a look at the best heated propagators currently available for amateur gardeners to use in their own homes.
Best heated propagators for your seedlings
Best overall heated propagator
Stewart We like this Stewart propagator for its versatility. Measuring in at 52cm long and 42.5cm wide, this gives you options as to how you use the space. You could fill the base with compost and sow seeds directly, or you could fill this with flexible combinations of pots and seed trays if you want to propagate different plants.
The rigid thermoform lid is completely transparent for good light transmission to encourage photosynthesis and healthy growth. The 22-watt heating element in the base of the unit will generate a steady level of heat, while the two vents in the lid will help you manage humidity and airflow.
Pros
- 22 watt heating element for robust warmth
- Two adjustable ventilation openings
Cons
- Too wide for most windowsills
Best windowsill heated propagator
Garland If you have an empty windowsill somewhere in your home, you could use that space to grow some gorgeous plants. This Garland propagator is designed especially to sit in such a space, measuring in at 79cm by 20cm by 18cm.
This propagator gives you three individual, vented propagators measuring 17cm tall that enable you to grow three different varieties of seed at the same time. This has a 13-watt heating element and the transparent covers are made from shatter-proof plastics. Some reviewers report seeds sprouting in as little as 48 hours using this system.
Pros
- Perfectly sized to sit on a windowsill
- Shatter-resistant, transparent covers
Cons
- Reviewers say power lead could be longer
Best budget heated propagator
StewartThis heated propagator is basic, a simple grow box with an eight-watt heating element, but it's perfectly capable of giving all kinds of vegetable and flower seeds, seedlings, and cuttings a warm start in life. Reviewers report this manages to create temperatures around 10 to 15 degrees above the temperature outside of the propagator.
This particular propagator measures 38cm long, so it can fit a few pots or seedling trays, and features simple on/off operation, so you can choose when to activate the heating element by turning it on from the mains. Temperature control also comes in with the single ventilation vent built into the lid of the box to regulate airflow.
Pros
- Simple, no fuss on/off operation
- Economic eight watt heating element
Cons
- Only one point of ventilation
Best heated propagator with grow lights
Erogeen Adding light into the mix makes for even more optimal growing conditions for all kinds of plants, from peppers to petunias. This tidy set from Erogeen gives you four seed bays, each of which feature their own adjustable LED lighting, and a heat mat that sits beneath them.
There are five adjustable brightness settings and four timing settings; four, eight, 12 and 18 hours, so you can make the growing conditions perfect for the seeds that you're germinating. This comes complete with 10 plant-label stakes and two small-scale gardening tools.
Pros
- Eight adjustable LED grow lights for each tray
- Four timer settings from four hours to 18
Cons
- Requires a USB power source
Best two bay heated propagator
Sankey Made in the UK, this Sankey Growarm heated propagator comes in attractive packaging, so makes a great gift for a green-fingered friend. This measures in at 38cm long giving you plenty of room for two types of seeds to germinate.
This propagator has two durable seed trays that sit on an eight-watt heated base, while the capillary water mat retains water and keeps things moist, as does the clear PVC cover that sits over the top of it all. Reviewers report being pleased with the bundled propagation guide.
Pros
- Comes complete with a propagation guide
- Has a water retaining capillary mat in the base
Cons
- Only stands at 19cm tall
Best three bay heated propagator
EarlyGrowMade from durable and robust injection moulded plastic, EarlyGrow's heated propagator is a strong choice for anyone looking to germinate multiple seed types as it has three individual bays that allow you to create mini micro-climates.
This will enable you to maintain soil temperature of approximately 16 to 19 degrees centigrade, ideal for the early cultivation of seeds and cuttings. The ventilation openings in each of the bays can be opened once seeds have sprouted.
Pros
- Three individual bays for different types of seeds
- Made from shatter-resistant plastic
Cons
- All three bays will be the same temperature
Best four bay heated propagator
Britten & James For gardeners that like to multitask, a four-bay heated propagator is the way forward, offering you a quartet of growing spaces for seeds that germinate at different rates. Reviewers report particular success with tomato seeds in this propagator.
This Britten & James option has four high-vented lids, so you won't be under time pressure to transplant the seedlings when they start to sprout. This boasts an eight-watt carbon fibre heating element for even distribution to maintain a compost temperature of 19 degrees Centigrade.
Pros
- Four seed trays for different seeds
- High-sided lids to allow for protected growth
Cons
- Relatively small ventilation holes
How we chose the best heated propagators
All of these heated propagators have been hand-selected by our team of Modern Gardens shopping experts. We carefully considered the size, functionality, and heat levels in our selection of the best. Our team has spent hours investigating and researching all types of propagators to make it easier for you to find the very best, and we'd never recommend a product we don't believe in.
Where possible, we also test and share the latest and best products you should know about. And with help from Modern Gardens Magazine, Garden News and Garden Answers, we share expert gardening knowledge to help you get the most from your product.
What should I look for in a heated propagator?
"When choosing a heated propagator, check the wattage output. The higher the wattage rating, the more heat it can produce," advises Geoff Hodge.
"Small propagators with a low-wattage heating element may not be able to generate high enough germination temperatures for some plants when kept in a cool or cold environment such as an unheated greenhouse in winter or early spring. So the higher the wattage the better, as you can get warmer temperatures."
Hodge also shares four features to look for in any heated propagator you're considering purchasing.
Ventilators: Easy-to-open ventilators will ensure you can allow air to circulate to prevent the build-up of excess humidity.
Clear lid: A tight-fitting, quality plastic lid ensures good light emission and keeps in warmth and humidity.
Deep base: A deep base, made from durable rigid plastic, will allow you to use small pots as well as seed trays and cell trays.
Wattage: The higher the wattage, the better the heat output.
What can I grow in a heated propagator?
Anything! Any type of seed that germinates in compost will flourish, and germinate more quickly, in a heated propagator. Cuttings will also benefit from the extra heat. Propagators are commonly used to germinate flower seeds and vegetables, such as salad tomatoes, peppers, cucumbers, and chillies.
Where should I place my heated propagator?
Propagators can be positioned anywhere, but they work best in a bright, sunny spot to benefit the photosynthesis process. Windowsills are a popular spot for propagators, or if you're fortunate enough to have a mains electricity supply to your garden greenhouse, that's an ideal place to put them.
The only time we'd advise not using a heated propagator is if it's placed in a sunny spot and it's particularly warm weather as you will run the risk of scorching delicate young plants.
What's an alternative to a heated propagator?
"Heating mats are an alternative option for providing bottom heat to otherwise unheated propagators," Hodge explains. "They work very simply; you just place the propagator on top of them. Like heated propagators, some have a set heat output, while others can be thermostatically controlled.
"There are times when a blanket is the better option. If you do a lot of propagating and want to heat the whole length or a large area of your greenhouse benching, for example, go for a heating blanket."
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Amy-Mae Turner is a Commerce Content Writer for Modern Gardens, Yours, Take A Break Pets, and A Modern Kitchen. When she's not pottering in the garden or mucking around in the kitchen, she can be found having doggy cuddles with her two beloved cockapoochis.