Hello All,

I have a large size slope in my backyard behind the retaining wall. The soil is very poor and it would take a lot to amend it. I am considering building some bottomless 2ft (LxWxH) planter boxes. As the roots grow, they will go down in the soil.

What wood should I use so they are sturdy, can take the full sun and water. Lastly, what coating/finish I should use for their longevity?

I am planning to build around 50 - 75 of these, and plant birds of paradise in them.

Any advice will be helpful.

 

I'd say let's start with some pictures of the area.

 

Thank you for your reply. At present, due to recent heavy rains, the slope is full of weeds, at least 4ft tall. I took a picture yesterday but you cannot make out the ground due to the weeds. Is there anything else I can provide that will help with this ?

Basically, to recap, just looking for a recommendation for the type of wood I can use then seal it for longevity. In searching, I notice a lot of people seem to use cedar fence boards to make planters. Is that a good choice ?

thank you.

 

Ground contact rated pressure treated wood would be my first choice. Some don't like the ideas of the chemicals in it potentially leaching into the soil so one could line it with plastic if that doesn't create the same kind of concern.

 

First I would consider the labor involved. Unless you are accustomed to making 50+ of anything most people will soon tire of the repetitive task. At the very least keep that large number in mind when coming up with your design so they can be rapidly fabricated. With that many you don't want to be getting fancy.

I would use pressure treated lumber. It's inexpensive and readily available. Most 5/4 and 2"x lumber is NOT rated for ground contact so you may have to special order it. Non-ground contact lumber will last a long time but not as long as wood treated to a higher degree for ground contact.

I would also consider using plastic barrels or pots. In quantity they can be surprisingly inexpensive and it's relatively easy to cut the bottoms out.