Winter - a time to put your hot bed down

Winter is a time of rest in the garden but for gardeners it is a time to do repairs and prepare for the upcoming growing months.

Paint or stain sheds and fences if required, undertake maintenance on compost bins, purchase seed and manure and clean and sharpen tools.

In the Victorian era winter was a time when you consumed the pickles and preserves you had set down in autumn or took advantage of a hot bed.  Hot beds gave savvy gardeners the upperhand on their contemporaries. 

They provide heat from the bottom, using manure rather than electricity, to grow salad crops or give spring germinating seeds a head start by up to a month.

Although they went out of fashion in the nineteenth century due to the prevalence of hothouses and greenhouses, hotbeds are still a very effective way to bring on early spring vegetables (as anyone who has planted seedlings into a fermenting compost pile knows) and evidence suggest they were relatively common from the thirteenth century.  It is said that the Roman Emperor Tiberius so loved his cucumbers that his gardeners grew them for him on wheeled hotbeds so they could be moved to shelter when the weather became unfavourable but it was the Dark Age Arabs of Spain and Portugal who made the first true hotbeds.  Small in size, two feet in height and about three square these hotbeds enabled them to get their produce to market quicker and therefore demand top price.  From the late Dark Ages hotbeds, it was thought, were introduced to Europe from the crusades (arabic numerals were thought to have been introduced at this time as well) and by the sixteenth century hotbeds were commonplace, including in universities with botanical gardens and then later used by laymen in household gardens.

To make a hotbed place fresh straw and manure treaded down to a 60 centimetre deep layer to ensure an even release of heat, on the ground.  Place on top of that a 20 centimetre layer, of equal parts of top soil and garden compost.  As long as you ensure a 3:1 ratio mix your hot bed can be as long as you want however if you choose to make it deeper it may go over the optimal 24 degree celcius temperature required for optimal seedling growth.  This can be offset by adding water, leaves and garden debris to ensure plants are not scorched.  Check with a thermometer regularly to determine if additives are necessary.

There are several methods to make a hotbed, whether in a greenhouse or outdoors however, all require that the sides of the bed are insulated and if outdoors that a cover be used.  Some gardeners swear by digging a pit 80cm deep in the ground, the earth being the most effective insulator, whilst others make do with a wooden box 80cm high, secured by stakes in each corner.  The climate in which you live may influence your choice of hotbox.

Leave your hot bed for a week before sewing seeds directly into the soil or placing seedling trays on top of the warmed earth. Hot beds will survive for approximately two months after which time the material on top will be well decomposed and you can use directly in your garden and the material on the bottom placed into your compost bin for further decomposition.

Winter planting

Sow seeds in trays or seedlings into the garden of: cabbage, cauliflower, celery, spring onion, onions, silverbeet, spinach and lettuce. Sow into the soil in warmer districts: carrots, parsnips, beetroot, peas and radish and in cool climates sow: broad beans, parsnips, turnips, Swedes and peas.  Plant seed potatoes, rhubarb, asparagus and strawberries.  Plant new citrus and deciduous fruit trees.

Winter Harvesting

In plentiful supply now in the garden are brussels sprouts, silver beet, cauliflowers, cabbage, parsnips, carrots, radish, spinach, leeks, kiwifruit, avocado, cherimoya, passionfruit, tamarillo and guava. Happy gardening!

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