Building a heating bed for overwintering Bonsai and Yamadori

I have used a heating bed for over ten years as the best way to increase the recovery of collected yamadori. The building of my new Greenhouse meant that I could have a new much larger heating bed. This is how I made it.

The whole frame is 12ft x 3ft The Timber was 9”x 2”. There is NO base to the frame, it is laid directly on the stone flags. The Timber is held together with 6” galvanised bolts.

A layer of silver backed ‘bubble’ insulation is laid directly on the floor. I could have used 1” Polystyrene block, but this proved OK.

To ensure that the moisture is retained the whole frame is lined with a Heavy Duty Polythene Sheet, and ‘stapled’ into position, particular attention is given to the corners.

Batons are screwed into the top of the frame to secure the Polythene Sheet, galvanised screws are used.

12 bags of Kiln Dried Sand are used to line the base of the frame, 2” deep. This Sand never ‘hardens’ and is a joy to work with. ‘Builders’ sand is not suitable. The Sand is then saturated with water

The heating cable (80ft long) is placed as shown and covered with a further 2” of Sand.

The completed Heating Bed, the cable is secured to the frame with a cable clip and the whole bed is saturated with water.

The raw yamadori now has a comfortable resting place to recover and thrive.