Making propagating benches

Earlier this year I came to the conclusion that there was no way I could continue to produce the plants that I do unless I invested in some proper equipment. Up until now I’ve been making do with a mix of stuff that really wan’t up to the job. With this in mind I went off and purchased some very sturdy and light aluminium propagating benches, they’re great, very strong but a little expensive. When I erected the polytunnel I needed some more, 5 meters more and something that I could use as a bench as well as propagating tables, these aluminium ones wouldn’t really have been up to the job. That’s where this design came from and with a few lengths of 2 inch square treated timber, some brackets and a hand full of screws I knocked up this in about an hour and a half.

Here’s what you need and how to do it. It was less than half the price of the bought ones and much sturdier but fairly heavy. The braces are short rather than the full length between the legs as this would have made it too heavy in my opinion but you could do that if you wanted.

What you need

  • 5 x 2.4m lengths of 2 inch square treated timber, this is standard at most building yards. Often its listed as 47mm x 50mm sawn treated timber.
  • 1 x 4.8m lengths of 19mm x 38mm sawn treated timber. Get it cut into two lengths of 2.4 though for easier transport.
  • 1200cm3 of planks for the slats cut into 500mm lengths. The reason that this is vague is that I’ve not easily found stuff that’s reasonably priced as you don’t want smooth planed wood. I used old pallets broken down and found them to be ideal.
  • 36 x 70mm wood screws
  • At least 52 galvanised 2 inch wire nails.
  • 8 x 60 x 60 x 40mm Angle Brackets
  • 80 round 1 inch headed wood screws (I used countersunk ones as it was all I had to hand but these will look nicer)
  • A cordless driver with a posidrive bit
  • A spirit level
  • A wood saw. Use an electric mitre saw if you can though as without it the job will take much, much longer.

Cutting the wood

Here’s a picture of the pieces that you’ll need for the main carcass. When I took this I omitted two more braces for the inside of the middle legs. There’s a picture further down and they’e listed, just not shown in this photo.

Carcass timber

Here’s the list of pieces that are all cut from the 2 inch square timber.

  • 6 x 800mm
  • 3 x 550mm
  • 12 x braces cut at 45 degrees with a 300mm long edge
  • 2 x braces cut at 45 degrees with a 200mm long edge (these are the bit’s missing in the photo)
  • 2 x 2400mm

Assembling the frame

Now you need to drill some pilot holes so that the screws line up correctly.

First drill a 4mm hole though the ends of all of the braces 90 degrees to the flat edge through the middle of the 45 degree face, this should be about 25mm in from the end.

Pilot holes

Next drill through the long 2400mm lengths, one at each end about 25mm in and one exactly half way (at 1200mm) down.

Pilot holes

Next line up one of the 550mm pieces at right angles to one end of the two long pieces making sure that the pilot holes in the long pieces are going in from the side not down from the top. It’s good to place another 550mm piece at the other end just to keep the frame square at this stage but as long as it’s almost square then it’s fine.

Timber frame

Then attach one of the corner brackets only putting one of the shorter screws in the centre for now as we just want to hold it in place, we’ll reinforce it with the rest later. Now repeat this with the other 3 inside corners until you have a frame that should have 4 lovely 90 degree corners.

Corner brackets


Reinforcing screw

Reinforce these with 4 of the 70mm screws, 2 at each end thought the pilot holes that you drilled earlier. This is why we drilled the holes first as to line this up without them in really hard.

Centre brace

Finally add in the centre brace, without it the frame can have a tendency to pull apart a little and we need them for the middle leg braces. Remember that I said I’d missed something in the photo, it’s the braces that go here later on.

First line it up so that it’s exactly in the centre of the two long pieces and screw through the pilot holes into the ends of the support. Add two more brackets here (unfortunately I didn’t photograph them), in the picture above they would be one in the bottom right corner and one opposite in the top left. These are really to keep the brace square as with just the end screw they would be liable to spin out of line. I hope that’s clear. Then just add all the remaining screws to the brackets to make it good and strong, you probably don’t need 5 on each face but screws are really cheap.

Finished brackets

Attaching the legs

Now we get to add the legs. Firstly we need to drill more pilot holes in the top face of the long pieces at the corners. They’re offset from the middle as you can see so that we don’t hit the screws that are coming in from the ends to hold the short edges in place, not too close but about 15mm. Line up one of the 80mm legs with the corner of the frame and drill a 70mm screw through the top to hold in in place. It won’t be perfectly vertical but as long as it’s aligned in the corner then it’s fine.

Reinforcing the legs

The easiest way to make sure that the legs are square is to use gravity, this is where the spirit level comes in, and maybe a friend if there’s one handy. First make sure that your frame is horizontal to the ground so that when we use the level on the legs we know that there is a 90 degree difference. Invert it so that the legs are pointing up and make it horizontal with the spirit leve.  Hold the leg so that it’s perfectly vertical in one direction, here I’ve aligned it with the long edge first. As long as it’s almost perfect the other way then we’re ok to continue as we’ll pull it vertical with the next brace.

First prime the screws through the flat top of all of the corner braces making sure that they don’t some all the way through the holes. Now take one of the longer braces and place it into the corner as shown then when the faces are all square drill in the bottom one only. With the spirit level against the leg and showing that it’s vertical again drill in the top screw. You can then do the other side of the same leg in the same way pulling it vertical in the other direction at this point. As long as it was almost vertical before then it will alighn just right at this point. Repeat this process for the other 3 corners.

Leg brace

For the last bit of the carcass we need to add the legs in the middle so that it won’t sag when it’s loaded up with plants. Place the leg in the middle on the long edge and line up one of the brackets with it as shown. You can remove the leg again here as long as the bracket doesn’t move then screw the bracket in place with 2 screws, not one as before as we want it to stay square. Place the leg back and put two more screws through the other face of the bracket.

Centre brackets

Repeat the process with the braces as before so the the leg it vertical back to front. This is the point where I realised that the single bracket wasn’t going to hold the leg vertical left to right as that we’d need another two braces here. That’s where the shorter ones come in as if they were the same length then the screws would all be in the same place and we don’t need much strength here, just enough to keep the legs straight and to stop them moving. The brace goes in the space shown in the picture below from the leg to the centre support.

Centre braces

Adding the top

All that’s left is the top. There are two ways of doing this but it’s up to you, I went for the way described here with a rebate as I think it looks neater. If you don’t want to bother or you simply prefer then you can nail the slats across the top of the bench from side to side on top of the frame. You’ll have sharper edges but it will save you time, you’ll have to picture what I mean as I haven’t got a photograph of it like that though.

I’ll add some photographs of this next bit later, hopefully the descriptions are clear enough though for the time being.

Take the lengths of 19mm x 38mm timber and measure lengths that fit between the end and centre braces for both the back and front on both sides. The reason that there aren’t measurements for these is that they’ll all be slightly different but it doesn’t matter if they’re up to 10-20mm shorter than the gap as long as there is enough to attach the slats to at each end. Prime these slats with galvanised nails by banging them in every 6 inches so that they hold in place as it’s easier when nailing them into their final place.

Using one of the slats to vertically align the side rail so that the top of the slat is level with the top of the frame at one end knock in the nail at then end you’re working at. Repeat this with the other end and then in the middle as the middle can sag a little, don’t expect it to be level all the way down. Once these three nails are in just bang in all of the others.

Once all 4 side rails are nailed in place it’s just a case of placing all of the slats on top to get them in place and then attaching them to the side rails, they should mostly be flush with the top of the frame but not matter if they’re a few millimetres out. Place them all where you want them before nailing any in as the gap between them depends on how wide they are. Once in place again attach the end ones first then the middle(ish) one by knocking a nail though the top at the end into the side rail. Repeat this with the rest by attaching the ones half way from the middle to the end next and then the rest. This way as you bang in the nails and the slats move around you’ll keep the gaps roughly the same all the way down.

Voila, you have some propagating benches. It might seem like a lot but it will save you a fortune for something of comparable stature, especially if you can fabricate the slates from pallets. If you’ve any questions about this then let me know and I’ll be happy to answer them.