Artificial lighting and heating have been used for decades by professional growers to produce plants all year round, allowing them to defy the climate and the season, but these systems have generally been unsuitable for the amateur grower because of their size and the amount of energy they consume. However, the increasing popularity of growing plants indoors and improvements in technology have meant a growing number of companies have harnessed the ideas behind professional growing to create mini grow units that can fit on a windowsill or shelf.
A heating mat warms up the soil to around 25C, encouraging speedy seed germination, particularly useful for plants like tomatoes and chillies which need a lot of warmth and a steady temperature. You can place seed trays or pots on the mat until you can see shoots appearing above the compost. Once the first set of leaves have opened take the pots/trays off the mat and allow the plants to grow on at a cooler temperature of 16–18C.
These units also come with lighting that provides the right wavelengths of light to promote healthy growth – normal household light bulbs don’t do this. Leave the light on for 12–16 hours a day to replicate the amount of light during the summer months. Look for units with LED bulbs, as these are the most energy efficient and they can be recycled.
Om Lars Lund
Danish horticulturist and journalist
Lars Lund has for many years engaged in the garden and greenhouse. Lars has published many books about greenhouses, and he has participated in many Danish horticultural TV shows. He is a walking garden encyclopaedia, and he has answers for most basic cultivation questions – also the more ambitious ones.
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