Hotbeds of activity

Vicki Cooke, kitchen garden keeper at the Royal Hampton Court Palace, reveals some historical tricks of the trade to force plants into growth out of season

Melons get a warm start by growing over a bed of decomposing manure Image: Vicki Cooke

Recently we have come to value seasonality, eating only what comes out of the garden in any given month. However if you were a rich landowner in the 16th century you wanted to show off by eating food out of season or from far away. It was a sign of your wealth that you could either afford the imported produce or that you had a team of skilled gardeners employed on your estate to force and delay crops out of season for you to enjoy.

When we look back at the gardeners of the past we can usually congratulate ourselves about our superior knowledge, better machines, effective pest control and waterproof yet breathable fabrics. But the ability to force and delay the ripening of fruits and vegetables to ensure a constant supply of particularly valued crops is something that we have lost. Why bother when we have supermarkets that can supply us whatever we want, year round. It was a mark of horticultural skill though, that they could encourage asparagus spears in January, trick apricots into fruiting in April or delay cherries until October. 

Inventive techniques

The problem for these early gardeners was that large glass panes had yet to be invented and the English weather is notoriously unpredictable, so how would they have gone about producing asparagus in January?

The answer is an inventive use of manure, sticks and straw. Wicker panels were used to make raised beds, where fresh stable manure and bedding would be packed in and a 30 cm layer of soil on top. As the manure breaks down it creates heat, which warms the soil above. This heat could be trapped in on cold nights by using rush matting to cover the beds.

The melon beds have a generous layer of manure covered with a quality top soil
Image: Vicki Cooke

Additionally, glass bell cloches were used to cover individual plants when they were small.

Tricks of the trade

I am in awe of the gardeners who could have achieved ripe melons in May, as just the smallest error could mean frost damaged, mouldy or scorched plants.

We have recreated a replica of one of these hot beds and we struggle to get ripe melons by August in cool years, but I don’t think we have enough volume to create the required heat. We also don’t have the staff to go out every chilly night to cover the beds, so we can’t get the plants started too early in the season.

Melons get a warm start by growing over a bed of decomposing manure
Image: Vicki Cooke

Instead, we use them from May to September for growing melons, then when they have finished, we plant winter salads. The beds were built using chunky landscape sleepers and were designed to run east/west with a higher north side. This soaks up the heat from the sun and reflects it back into the bed. The area is surrounded by a fence which breaks up the prevailing winds. Even without the manure, just these simple measures give us an extra few weeks of growing at each end of the seasons, which makes them perfect for winter salads. 

Cropping through winter

From mid September to early October we sow direct in the beds the seeds of kale, chard, winter lettuce, cress, rocket, radicchio, purslane, corn salad, American land cress and mustard.

A hot bed can be used to grow winter salads
Image: Vicki Cooke

We can slowly harvest these from November through to April. Growth becomes very slow through December and January as light levels are too low but will pick up quickly in early spring. The only pest around in winter is the pigeons, so we put all the crops in the brassica family in one bed and net those, the rest will be fine without protection. As soon as the weather warms in April, these will run to seed, but that is the time to swap over to the summer crops again. As we no longer have an eager oligarch to please, we can stage a return to eating seasonally.

 

 

Vicki Cooke

About Vicki Cooke

Vicki has had a varied career in horticulture, from vegetable seed producer with the Heritage Seed Library to conservation manager with Plant Heritage, via the walled kitchen garden at Hampton Court Palace. Now working with the National Plant Collections, the perfect place to combine a love of plants with an interest in the diversity, history and culture associated with them. Always with a soft spot for edibles and a member of the RHS Fruit, Vegetable and Herb committee.

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