Introduction: DIY Window Planter Box
Window boxes are a great way to add colour and character to a house. What's more they're incredibly easy to make and install.
There's so many ways to make them, this is just one of them. The only thing you need to consider is how the timber will stand up to moist soil and making the boxes free draining. Other than that there are so many ways of putting one of the these planters together.
Step 1: Cut and Build the Box
I used treated pine as my timber, lengths of 70mm x 19mm. If you're able to find wide boards then this step will go very quickly.
I created 3, 70mm high high frames using galvanised screws, then joined those frames together. During the initial joining the boards twisted a bit but it was easy to push them into square.
Once of the frames had a bottom attached using a few of the boards pushed together. Remember, this isn't going to take too much weight so don't be too worried about adding supports. I did however add 3 cross pieces inside the box, these will help to spread the load across the entire bottom.
To join up the frames I used a few pieces of wood in the corners and screwed the frames to that.
Step 2: Seal the Inside and Add Plastic Lining
The wood that I used was pressure treated but only rated for above ground use. To get around the issue of damp soil sitting on the timber I lined the inside of the box a plastic bin liner, but before doing that I sealed the entire box with boiled linseed oil.
Linseed oil isn't the most durable of finishes but for the inside, considering it's pressure treated, it's just an extra layer of protection. On the outside though it will allow the wood to grey more naturally. It will need to be reapplied occasionally but again, because it's pressure treated wood it's not going to rot. Well, not in my lifetime anyway.
After stapling the plastic to the inside of the box trim the excess. This will be covered in the next step.
Step 3: Add Decorative Trim and Drill Some Drainage Holes
Now you can cover all the corners with trim. I used 42mm x 19mm treated pine and attached it with pin nails. This step is optional but I wanted to cover the screw holes because I had another floor standing planter with the same design in the yard.
I won't go into too much detail on the trim because it's mainly decorative but it's very important that you drill a few drainage holes in the bottom. I used an 8mm drill bit and added 8. Once the soil is added at the end you can come back and poke holes through the plastic.
Step 4: Install the Box and Plant
I have a brick house to I need to drill some holes and add wall plugs. The process for a timber house would be the same besides this step.
I attached 2 100mm x 150mm galvanised steel L-brackets. In retrospect I could've gone one size bigger because these are very 'springy' under the weight of the dirt, but I'm happy to leave it as is.
I centred the box underneath the window and bolted it to the brackets. Because the timber is only 19mm thick I didn't feel comfortable screwing it into the brackets because 19mm of thread isn't very much. Bolts ensure the box will never fall off the brackets.
All that was left was to add some soil and compost, plant some strawberries, then give it a good water. In a couple months I should be waking up to fresh fruit direct from my window.
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