Gardeners are always keen to get growing as early as possible, but with low light levels and cold temperatures, as well as sudden frosts, lasting well into spring, success is not guaranteed when only sowing direct outdoors. The answer is a heated propagator - a unit that allows you to start your vegetable and flower seeds off warm and cosy indoors, with a much higher rate of success, and earlier results.
Sowing indoors in a propagator also gives tender and half hardy plants a better chance of surviving to be planted out in late spring, and these units can be the perfect place to encourage cuttings to root too. They are perfect for gardeners who don't have access to a greenhouse or polytunnel, as many units are made to be used on your windowsill, meaning no matter what size your home and garden, you can enjoy sowing and growing a range of blooms and produce without having to wait until April or May.
How to choose a propagator
Heated or non heated
A propagator can be as simple as a basic clear plastic lid over a basic plastic tray. In a cosy, bright spot in the home the clear cover will let light through and provide a micro-climate that’s sufficiently buffered from the changes in your room temperature (and certainly a lot warmer than outdoors).
A heated propagator goes one further by providing bottom heat to encourage seeds to germinate, sprout and root. Heated options do – of course – cost more than the more utilitarian non-heated options and will need a source of power.
Simple basic necessities include air vents that allow you some degree of control over the internal temperature (allowing condensation to dissipate) and some units also have easy hydration options so you can water your seedlings more easily.
The best heated propagators
Suttons Super 7 Electric Propagator
If you’re new to the world of propagating plants and perhaps don’t have an outdoor space available then this all-in-one option from Suttons really has all you need to get growing. It’s tailor-made for your windowsill, being just 18.5cm deep and 76cm long, allowing you to turn your sunniest spot into your own indoor grow zone.
There are seven separate compartments, minimising the volume of air circulating and keeping each compartment cosy and warm, and adjustable vents on every section allow you to cut down on condensation and release a little heat should it be required. A simple 13w heating element in the base provides consistent even heat across all the units.
Selections Jumbo Windowsill Heated Plant Propagator
If you’re sowing en masse and don’t require separate compartments then this simple all-in-one unit is perfect. It’s large and lengthy at 80cm but at just 20cm deep still thin enough to place on a windowsill.
Either fill the 5cm deep base with pots or fill directly with your chosen compost and sow with impunity! Vents in the lid prevent condensation – head-height is 12cm here – and a thermostatically controlled 12w heating element will maintain a constant 21 degrees centigrade.
Stewart Thermostatic Heat and Grow Electric Propagator
This premium electric propagator goes the extra mile, giving your growing more room to breathe and comes complete with a set of trays and 10 pots to cater to plants and flowers of any size. Its 22w heater has the capacity to quickly heat up and maintain temperature within the main space and the thermostat control allows you to dial in a heat of between 18 and 23 degrees then let the unit keep that constant without further intervention. Of course, vents on the top allow you to release hot air and moisture should it be required.
28cm height gives headroom for your cuttings while 52cm width and 45cm depth make it perfect for a sunny kitchen worktop, table or bench.
Hydropod Cutting Propagator
- Buy now from Dobbies (£119.99)
If finding a sunny spot is a problem – or if you simply want to boost your growing speed and chances of success – then a heated propagator with lighting will give your plants the best possible start. As you can imagine these units combine all the cosy, warm climates of a heated propagator but add lighting into the clear lid to either boost what available light there is, or provide a perfect perpetual sunny day.
This hydropod cuttings propagator is made specifically for cuttings, and goes one better, by ‘misting’ them with water. Simple place your cuttings on the sponge discs, add some water and switch on.
Riogoo Seedling Heat Mat and Thermostat
These mats are popular with professional nurserypeople and gardeners who have growing tables in their polytunnel or glasshouse. Lay the mat and place your pots and trays of seedlings and cuttings on top, then set the thermostat and let it deliver gentle warmth exactly where it’s required.
The 24cm by 52cm mat is 100% IP76 waterproof so you can water your plants exactly as normal, and has a scuff resistant coating so it can take more than a few knocks. The digital thermostat lets you set a precise temperature and a separate wired soil probe measures the temperature in your pots meaning whatever you set will be maintained with 100% accuracy.
Suttons Geopod Large Heated Propagator
Sutton’s Geopod is the state-of-the-art way to grow plants like herbs and salads indoors through winter. Its 112cm x 63cm x 29cm high growing zone will accommodate larger pots than most seed sowing propagators, and the thermostat is digitally controllable to maintain the entire space at anything from 5 degrees to 30 degrees centigrade.
The icing on the cake comes in the form of two lighting systems mounted in grooves in the lid, lined with nano reflectors to reflect back 99.9% of previously lost light. This even glow creates healthy growth, avoiding the legginess that can result from growing indoors through a dark and gloomy spring.
Looking for more propagation tools and gadgets? Go here.
Using your greenhouse in winter
If you’re thinking of growing through winter on a much larger scale then a greenhouse can provide safe shelter for your less hardy plants. A few simple tweaks and an affordable purchase can make it effective all year round.
Of course genuinely ‘heating’ a greenhouse through our coldest cold snaps would be a 24/7 job and an uphill battle all the way, but a little insulation and a helping hand from a simple small heater is certainly better than nothing and may make all the difference.
A little greenhouse maintenance is your first step. Ensure that overlapping glass sufficiently overlaps, clips are tight, windows and doors fit frames snugly and putty isn’t cracked or absent. The more you can insulate and cut out drafts the less hard your heater will have to work.
Try lining draughty areas with bubble wrap, or create your own smaller internal ‘greenhouse within a greenhouse’ with a garden cane and plant tie frame and a bubble wrap outer skin. The more layers you can put between outdoor and your inner growing zone the warmer it will be.
Finally add a heater of your choice. There are electric options of every size (which will require power, of course) and old-fashioned burners (which could well be off-limits if you’re cutting down on burning fuels).
Lighthouse 2kW Greenhouse Heater
This simple but powerful industrial-strength option has the power to heat 20 square metres thanks to its fan and two heating elements. Both are completely adjustable allowing you to set a range of temperatures and fan strengths for your needs, from a constant warm glow through to a hot blast to quickly take the chill out of any outdoor space. An adjustable thermostat allows you to set a temperature then leave the unit to achieve this, and then maintain it indefinitely. Or, in summer, if you’re simply looking to keep air circulated it can run in fan-only mode, keeping air moving around your growing space.
Elixir Gardens TH01-D Tube Heater
This simple electrical option comes in a variety of sizes and power levels and can easily be wall or floor mounted. Its efficient electric heating coil heats a tube to deliver an even flow of heat across a bench or beneath a working area. And to prevent any risk of burns – either to you or to your plants – it comes with optional covers to keep delicate leaves at bay.
Digital controls give you precise adjustment of heating times, allowing you to set it to only heat during cold winter nights, or come on for two hours, then off for two hours, for example, to save energy.
Daniel Griffiths is a veteran journalist who has worked on some of the biggest home and entertainment brands in the world. He is a serial house-renovator and home improvement expert, taking on everything from interior design and DIY to landscape gardening and garden design.
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