BUYERS’ GUIDE
Geoff Hodge investigates propagators to give seeds and cuttings the best start in life
Even the most seasoned gardeners get a thrill from propagating their own plants. 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 awarm environment. And to get the best results, you’ll need a propagator.
This 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 awarm 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.
There are three main types of propagators: unheated, heated and heated with thermostatic control. They come in a range of sizes and for keen propagators, bigger is better – for example, long, windowsill models are ideal for people with limited space inside the house.
Simple covers
An unheated propagator is simply a clear plastic lid over a tray. It helps maintain high humidity, important for good germination and rooting and helping prevent compost from drying out prematurely. But the heat level inside depends on the ambient temperature around it, so it has to be kept somewhere warm and, of course, in good light. These are perfect for use in the house or a conservatory or heated greenhouse. But in an unheated greenhouse or other cool or cold environment, temperatures inside can be too low to produce good germination –maybe none at all.
Ideally, the lid will have moveable ventilators to adjust the humidity if it gets too moist inside.
Heat is best
Heated propagators give you far more flexibility. They produce better results with a wide range of plants, creating awarmer 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.
When choosing a heated propagator, check the wattage output. The higher the wattage rating, the more heat it can produce. 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.
Heated propagators divide into those with a thermostat, so you
