Heated propagators will ensure that your seeds or cuttings have a constant steady temperature. Head gardener at Stockton Bury, Tam sin Restore, puts a selection through their paces and recommends some best heated propagator options.
You also don’t need to worry about sudden drops in room temperature if the propagator has a thermostat. For safe storage, keep your propagator in a shed or garage rather than in a greenhouse where water is used nearly all year.
With seven individual little units, you can sow several seed varieties with no risk of contamination from disease. The vents at the top of each lid are easy to open, and as the units are so small, they are simple to wash up in a normal household sink.
Pic credit: Howard Walker Fixed Temperature Propagator Base Simply place your own seeds trays of seedlings or pots of cuttings onto the unit.
Pic credit: Howard Walker The BioGreen Warming Pad may be about as simple as it can get, but what a fantastic idea for those short of storage space. If you are taking a few cuttings or sowing just a few seeds every year, then this pad might be just what you are looking for (it can be rolled up to store).
The rubber mat is splash proof, so can be wiped clean, and pots that have drained after watering can be placed back on it. (As a rule, remove pots and trays to water them, then place back into the propagator once drained).
Pic credit: Howard Walkerton Vito pod Propagator is far from a windowsill model. The base is evenly heated and is easily controlled, allowing you to set a temperature of between 5 °C and 30 °C.
The clear lid lets in the maximum amount of light and has generous vents, which are the keys to its success. Pic credit: Howard Walkerton Sahara Heating Mat from BioGreen is a really useful piece of kit.
The mat offers even heat distribution across a bench, and works best when placed on insulating material, such as polystyrene. It’s perfect for overwintering tender specimens, germinating seeds and taking cuttings.
If you are overwintering or propagating plants in an unheated greenhouse, then this mat will allow you to just heat one area, which will be far cheaper. Don’t forget to sign up for our monthly The English Gardener newsletter, bringing you all the growth your own advice you need throughout the year.
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The rating is also determined by our subjective opinion and the brand preference based on the reputation or market share of a particular Brand/Company. The propagator units are ideal for growing seeds in volume and particularly suited to larger cuttings.
Size Check: 76 cm (30") Long 18.5 cm (7.25”) Wide 20.5 cm (8”) High Just as the fork and spade are essential tools of the gardener, a propagator is part and parcel of the seed-raiser's armory.
In order to germinate from a seed, plants have three basic requirements: moisture, oxygen from the air and adequate temperatures. These may sound simple enough to provide but at no other time in its life is a plant more vulnerable to changes in the environment than during the process of germination.
Young tissues are very fragile and have not yet had any time to build up resistance to sudden changes in temperatures and moisture. Others may even need a mixture of high and low temperatures each day in order to grow.
It makes sense to be able to control the conditions affecting germination, tailoring them to the needs of each specific plant rather than leaving it to chance. In its simplest form, a propagator can be just a sheet of glass or polythene covering the tops of the seed trays.
This cover will prevent seeds from drying out, whilst keeping them slightly warmer than the surrounding air. There is little control and when exposed to the direct rays of the sun, temperatures can quickly rise, killing both seed and seedlings.
As light is not required for many plants to germinate, many people place their seeds in the warmth of the airing cupboard (drying closet). The main drawback with this particular method is that seeds need checking daily for signs of germination.
However, depending upon the degree of sophistication, these may be ten or more times as expensive as the basic unheated types. The basic models are usually composed of two components, a tray in which to place compost or pots of seed and a transparent cover which rests on the rim.
The cheapest are made from thin, flimsy plastic and are ideal for rough use, being cheaply replaced when damaged. Slightly more expensive types are constructed from better quality materials such as polypropylene, which does not shatter or break.
The larger canopies of many better quality types prevent sudden sharp changes in temperatures and humidity. Most models also have ventilators let into the top to allow air to circulate, whilst reducing high temperatures and humidity.
The size of aperture is controlled by either louvres or rotating discs, and by this method the internal environment can be roughly set to the prevailing weather conditions or the needs of the seedlings. This may be a glasshouse heater, radiator or even sunlight, which during late winter or early spring may be extremely erratic.
The biggest step forward when choosing a propagator is selecting a model which has its own integral source of heat. The vast majority of models are powered by electricity which means a mains supply must be located close to where the propagator is to be sited.
When in operation the heat from the cables or mats is conducted into the pots or compost containing the seeds. The higher the wattage, the more responsive the heating unit, and its ability to give a swift increase in temperature.
A low wattage model may struggle to produce adequate temperatures for germination than its more powerful counterpart. Again, as with unheated models, because the heat source is not under such strict control, keep a check on the temperature inside the propagator, ventilating the seedlings during hot spells.
The beauty of the thermostat is that it allows the heating unit to rise to its pre-determined temperature, then the power is switched off. Besides producing a more even growing environment for your seeds, it also saves power further reducing the cost of heating.
With the advent of computer technology, some manufacturers are installing microchips into their heat regulating devices, further streamlining their design. Certain manufacturers have taken this idea a stage further by producing models which have variable heat control in each separate compartment.
These may have extra ventilation facilities such as louvres or even electric fans in expensive models. As part of the kit many manufacturers provide a number of different sized seed trays to fit into their heated bases.
Whilst most standard electric propagators are too large for the average windowsill, a few manufacturers have come to their aid by producing models which are specifically designed for use indoors. Growing on windowsills means that light is directional, so ensure that the individual units are removable and can be turned round.
Many models have bases constructed in heavy-duty plastic although some are made in aluminum or even timber. Prices vary tremendously depending upon the power of the heating unit, the size of the propagator and the material it is constructed from.
If you need a large propagating unit it's most economical to make your own using a wooden frame, insulation, sand, heating cable and a thermostat. If you have to raise a considerable number of plants each year then even a large heated propagator may not be suited to your needs.
Certain models come with a polycarbonate surround to conserve heat around the seed containers, important if you have a drought greenhouse! Many manufacturers install a small bulb in their propagators which is illuminated when the machine is in operation and is receiving power.
As an extra precaution, it is wise to install a power breaker into the main plug socket. These inexpensive devices are easy to install protecting both yourself and your equipment should there be any chance of a short circuit or overload.
And remember that with so much water about and probably an aluminum structure to the greenhouse, electrical safety is absolutely vital to prevent damage both to your equipment and, more importantly, harm to yourself.