How to build a giant heated propagation unit

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Now that it ’s finished I ’ve consolidate 4 late postal service into one , keep open startle about .

The first business was to clear out the nursery so there was elbow room …

I have begun thechangesneeded in the greenhouse to reach prime propagation this year . So far this has necessitate make out down the long staging to outfit in its new home at the threshold - end of the greenhouse and trimming down and move the existing short staging to the other side , next to the existing gravel blind drunk bed , see below . In hindsight I could have reach the same outcome with less cutting and mucking about if I ’d left the short scaffolding where it was and just foreshorten the long scaffolding down to fit a unlike spot ( as per the diagram I drew antecedently … ) . Never take care , kept me busy for a twosome of hours . All this is really about making space for the large heated extension bed . I have the dirt heating cable , I just need the wood . Next step will really be to move the pot judiciary from the glasshouse to the shed to make a bit more room . I have half an idea of making it bigger but that ’s not a high priority – one for next winter perhaps , although if my broadcast plans go as intended I may repent not scale it up now while there ’s not much else on .

Next I start to build the woodland soma …

I yield a visit to Oxford Wood Recycling which is a societal enterprise I ’ve used before when I ’ve needed cheap timberland . It ’s a mo of a trek , 20 unmatched miles , but well worth it . From their Aladdin ’s Cave of wood I bought some long lengths of 4×1 board which they reduce to required size for me on site ( £ 14 ) . These will mold the horizontal section of the frame , about 233 cm or 7’6″ tenacious . I ideally would have preferred older scaffold boards or 6×1 planks but the former were too pricy and they did n’t have enough long objet d’art of the latter . Never bear in mind , I will double up on 4x1s and so have 8 in of profundity to trifle with in the frame . I already had pallet rails ( £ 0 ) which are very solid , which I cut down to 90 cm in distance to form the legs for the bench . If I did n’t have these I ’d have either forage for more pallet or buy 3x2s from the Natalie Wood castle .

Legs eleven. Or six.

One of the unforeseen downsides of maximise the size of the work bench vs the nursery is that there is n’t much wiggle room to build in there so I first built the sides in the shed . The 4×1 planks were screwed square to the leg with 2 in screws , flush with the tops , two board on each side .

I added an extra wooden leg on each side for the interest of validity and so I can brace the radical a morsel more . It will finally be holding a heavy burden of sand , water and compost so it need to be firm . I do n’t want it all falling through the middle and wreaking generation havoc .

It would have bet neater to put the middle legs on the inside of the box frame but I wanted to have an continuous run inside the frame to make it easy to spread out the liner when the time follow .

Legs eleven. Or six.

I should ’ve bought another couple of 4×1 board for the bottom shelf but miscounted so will buy a couple in B&Q when I get the other moment I ask . I moved the shorter side pieces into the nursery and after a morsel of staging ruffle , screwed in the side pieces ( 93 cm or 3′ ) which completed the canonic frame for the bench .

After dispatch the basic material body , the local DIY department store ( B&Q ) was my next port of call .

I ’ve used a sheet of 18 mm MDF board ( £ 19 for 8’x4′ ) for the stem which was abridge to size for me in the shop . I love that cutting inspection and repair , I ’ve always desire to have a go at the big saw rig . Sigh . Anyway , I drilled and screwed the fundament onto the underside of the side track , using plenty of screws . Wet sand is pretty heavy so I tot up some excess bracing underneath the base , incline diagonally from the corner ramification to the central legs and straight across the centre . Hopefully that ’s enough … !

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

Since I ’ll be inflame the judiciary I desire to verify the heat conk where it is needed , into the sand and more significantly the flora , not down into the cornerstone . I had a brainwave and enquire my local detergent builder if he had any offcuts of Celetex , splendid insularity and just the job . Not only did he he have some knocking about but he also shake off them off to the house ( £ 0 ! ) , save me a few quid . Thanks Mick ! I ’ve edit it to size and ram it in , overnice and cozy .

As the bed will get a circumstances of lacrimation , it need to be lined to forbid the wood from going soggy and quickly rotting in the humidity . I ’ve cut to size a canvass of damp proof tissue layer ( £ 20 for 4mx3 m in B&Q ) , a pond lining would play too . I have used a twofold layer of DPM to be on the good side , this should be courteous and watertight .

Base for a heated propagation bench

MDF base secured to box frame

I did consider whether to isolate the sides as well as the base as I have left over Celetex , but I would lose about 3 sq feet of propagating space as it ’s quite fatheaded . I figure that outer space is more important to me than some lost heating .

For the bottom itself , I am using sharp sand ( £ 20 for 13 heavy bagful in B&Q ) , part because it is sleazy but also because it has an open structure that should aid capillary activeness into the pots ( as a source of piss ) . A 2 inch bed of sand first , level off .

The soil thaw cable television service ( £ 34 , Amazon ) goes next , carefully laid out on the Baroness Dudevant . The closer you coil it the blistering it will heat the surrounding area but plain the less outer space it will cover . I have a 12 m cable so I have aimed for 12 - 15 curium gaps which should be just about enough to warm the whole bed .

Bracing for the base of a heated propagation bench

Extra bracing for the base.

Per the instructions I plugged the cable in for 10 minutes to make it more waxy but it was still a Book of Job to get it to lie where I wanted it . As you may see it terminate up quite wiggly . I found that the overseas telegram is n’t quite long enough for the area of bed I have but the 24 molar concentration cable would have been too long . In the end I compromised and prefer to have a coolheaded terminal of the layer with no cable .

I ’ve drilled a hole for the overseas telegram to feed into the bench at the right meridian . This is also where the the thermoregulator would be wired in , if / when I get one . Once in place I covered the cable’s length with a further 2 inches of sand , leveled off .

Although the bench is in the greenhouse , I will be capable to more closely control the humidity on the bench if I allow a unopen domain . This is particularly of import for cuttings while they are in that vulnerable not - yet - rooted stage . It will aid keep the warmth in and knock back any strong sun a bit . I ’m doing this with slightly opaque 250 micron polyethylene sail ( £ 11.99 for 2mx4 m roster on Amazon ) which is typically used for polytunnels so it ’s prissy and strong and ultraviolet radiation static . This is stretch over hoops made from 25 mm plastic piping which I have had lie around for years ( £ 0 ) . I necessitate to be able to open up it well for access and ventilating system so I ’ve attached the sheeting firmly on the rear side and just left it loose on the front so it can be furled and unroll over the hoops . To make this a little well-situated I ’ve staple the front end to a distance of battening to give it some weight . I ’ve also cut across the outside of the remainder hoops , using the same polythene , so that there is a closed in environs . I ’ve just rationalize to determine and staple it to the hoops .

Greenhouse storage space

Plenty of storage space.

So that ’s it finished ! My out of pocket expense were as follows :

The total monetary value of building this judiciary , 21.3 sq ft of propagating joy , was £ 132 , give or take . It ’s a non - petty amount when tally up like that , but still , that equates to £ 6.20 per square ft , even better value for money than I estimatedhere . This is agency , way less per sq ft than the cost of buying a heated prop unit . And , it ’s much much boastful . I could add a thermostat for another £ 25ish , which would tolerate closer control of temperature and make it cheaper to run . Might do that , will see .

If I was n’t so raring I could have scavenge for more of the wood as well as the insularism offcuts which would have reduced the toll even further . Overall , bargain ! !

insulating a heated propagation bed

Snugly insulated.

I ’ve still got to get the electrical energy connected properly but I would have had that cost if I had just corrupt a heated up prop unit . For now I ’m just running it via the extension cable from the shed which significantly has an RCD plug on it .

It ’s already fulfill up with germinating seed , cuttings , seedling and so on .

UPDATE 22 - Feb-2018

The work bench has been in action now for over a year . I did contribute a thermostat which allows me to more closely control the temperature as well as making it cheaper to run . The judiciary has been in constant use , for seedling , for cutting , for overwintering fragile plant life . I have find that the sand needs watering once a workweek or so – two or three tearing cans does the trick . This is because wet sand convey high temperature well than dry sand . The social structure of the workbench has held up very well . With the cover conclude , condensation does build up on the interior of the cover which in itself is not a vast issue , but I have rule that this drips off when I reach the cover . Some of these drips find their way down the back of the binding and underneath the bench and the MDF base is look a piddling puffy in a couple of places . In hindsight I might have used marine ply for the base rather , or just treated the MDF with wood life preserver to protect it . I still have n’t father the electricity hooked up the right way , I must get around to that …

Heated propagation bed, greenhouse.