After completing the basic frame, the local DIY emporium (B&Q) was my next port of call.

Base for a heated propagation bench
MDF base secured to box frame

I’ve used a sheet of 18mm MDF board (£19 for 8’x4′) for the base which was cut to size for me in the shop. I love that cutting service, I’ve always wanted to have a go at the big saw rig. Sigh. Anyway, I drilled and screwed the base onto the underside of the side rails, using plenty of screws. Wet sand is pretty heavy so I added some extra bracing underneath the base, running diagonally from the corner legs to the central legs and square across the centre. I hope that’s enough…!

Bracing for the base of a heated propagation bench
Extra bracing for the base.

I made the bottom shelf mostly from bits of battening from the dismantled staging  (£0) but I needed a few more (£10). 

Greenhouse storage space
Plenty of storage space.

Since I’ll be heating the bench I want to make sure the heat goes where it is needed, into the sand and more importantly the plants, not down into the base. I had a brainwave and asked my local builder if he had any offcuts of Celetex, excellent insulation and just the job. Not only did he he have some knocking about but he also dropped them off to the house (£0!), saving me a few quid. Thanks Mick!  I’ve cut it to size and jammed it in, nice and snug.

insulating a heated propagation bed
Snugly insulated.

As the bed will get a lot of watering, it needs to be lined to prevent the wood from going soggy and quickly rotting in the humidity. I’ve cut to size a sheet of damp proof membrane (£20 for 4mx3m in B&Q), a pond liner would work too. I have used a double layer of DPM to be on the safe side, this should be nice and watertight. 

Annoyingly, I ran out of time again, will have to finish it next weekend.  Just the sand and the cover to add now really. 

Getting impatient now, I’m in a race against time as I am expecting a delivery of seeds in the next week or two.

I’ll be back with the final (I hope…) installment next week.