Electric Heated Propagators
Introduction
Late winter and early spring can be an ideal time to sow vegetables, especially slow growing plants that need a long growing season to ripen fully, like tomatoes, peppers, and aubergine. The problem is that it is too cold to sow seed outside, and sometimes inside too. This is where heated propagators come in useful.
If a gardener has a warm light environment to protect early sowings, like a conservatory or sunny windowsill, a heated propagator may not be required. Where heated propagators make a difference, is in environments with good natural light but with relatively cold air. Rather than heat a whole room, a heated propagator provides the ideal temperature for seeds to germinate within its protective casing.
I have found my heated propagator to be a good investment, as it speeds up germination and makes the whole process more reliable. I place my propagator on my kitchen windowsill, and I have found that seeds germinate faster inside the propagator, meaning that I can grow more plants by moving the seedlings after germination into my polytunnel, freeing up space in the propagator for more sowings.
See the video below, and scroll further to see a full introduction to the benefits and buying considerations.
Step By Step Video
YouTube Video
Advantages Of Heated Propagators
Seeds germinate faster in a heated propagator
Examples include tomatoes or cucumbers germinating in 2 to 3 days rather than 7 to 14 days on a sunny windowsill.
Savings on seed
Seeds germinate more reliably in heated propagators, meaning a gardener can sow less seed for the desired number of plants.
Efficient use of energy
Rather than heat a whole greenhouse, a heated propagator only heats the air within the propagator itself.
They increase enjoyment
There is satisfaction from having a gadget that works and helps speed up nature, to have seedlings ready to take full advantage of warm spring weather when it arrives.
Considerations Before Buying
After germination, where do the seedlings go?
Electric propagators are most useful for gardeners with greenhouses, growhouses, hotbeds, or cloches where they can grow on seedlings in a protected environment. Otherwise, when seedlings are removed from a propagator, the shock of cold may negate the advantage gained by fast germination.
The same results can be achieved with a sunny windowsill
If the air temperature is warm enough, there may be no need to invest in a heated propagator. A heated propagator is likely to make the biggest difference in the colder months from January - March. When the weather starts to warm in spring, a heated propagator may not make much difference to germination times.
The cost of electric propagators
Depending on functionality and size, the price range is upwards from £20 with some best selling brands at nearer £200 for larger growing spaces.
Care and maintenance
Supervision is still needed with heated propagators. Heated propagators do not cool down the soil on sunny days – they simply turn down the heat (if they have a thermostat). This means that in hot weather the gardener will need to open the air vents. Equally, in very cold weather, it may still be necessary to cover heated propagators, for example if sited in an unheated greenhouse. The heating element may be overwhelmed if outside temperatures plummet too low.
Space
Electric propagators need to be put somewhere. If the only location available is a windowsill in your home, this may already be warm enough for good germination. Heated propagators are most useful in greenhouses, or cold rooms with good light in a house, garage, or garden shed.
How I Use My Heated Propagator
The video shows the Sankey Growarm 100 heated propagator that I own. It has done a good job, significantly speeding up germination times and making germination more reliable – meaning I need to sow less often and use fewer seeds.
My model does not have a thermostatic temperature control to measure and regulate temperature. When the weather warms I take the plug out, preventing it getting too hot inside. The propagator comes with a plastic lid, two seeds trays, a capillary matt, and the base that contains the heating element.
The first step is to prepare the pots or seed trays. I do not use homemade compost as it can contain weeds. A fine crumbly shop bought compost is ideal. After filling the pots, I moisten the soil using water from a tap – fresh water helps to avoid disease.
The next step is to wet the capillary matting under a tap, and place it on the bottom of the heated propagator. The matting provides moisture to the growing environment, but also helps to keep the bottom of the heated propagator clean.
I use the propagator for seeds like tomato, pepper, chilli, cucumber, and inca berry, for growing on in my polytunnel. I space out two or three seeds per pot, and cover with a fine layer of vermiculite. After sowing, I don't water the seeds in, as there is sufficient moisture in the compost from my initial preparation.
When all the pots are ready, the final step is to cover the propagator with its lid. Closing the vents on the propagator creates a humid growing environment ideal for germination. With closed vents, the pots do not need further watering.
I place my heated propagator on a bright kitchen windowsill that only receives sunshine in the morning. The lack of direct sunlight from the afternoon onwards can cause the air temperature to fall below the ideal temperature for germinating plants.
As soon as germination starts, I gradually open the vents a little each day to gently acclimatised the plants to normal conditions.
When the seedlings have developed true leaves, I remove them and grow them on in my polytunnel, leaving the propagator free for the next sowing. If more than one seed germinates in a pot, I divide the seedlings and grow them on in separate pots.
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