Looking for advice on best materials to build large garden beds on a large deck

[toddt]

Hello All,
I just signed up today as I enter my third year of gardening. I look forward to responses to this and all future interactions. Here is my situation.

I have a very large deck (48'x16'). unfortunately, my property gets very little sun, but the deck, however, does. This has become our garden area. 2 years ago I built a 4' x 2' raised deck box. I used pressure treated posts on the exterior for the legs and all other boards were cedar. When all was said and done, the box material list cost about 225.00+. then I bought a similar bed from tractor supply the following year for well under 200, but not made of cedar and not nearly as sturdy. I would like to make my own as I seem to keep needing to add more beds. I don't want to sound arrogant, but I can make a far superior product then the store bought junk. Can anyone suggest a material other than cedar ( so expensive) that will work in this application? pressure treated boards are a no no inside the bed correct? I am a beekeeper and have plenty of wax at my disposal. would regular pine treated with bee's wax work? I don't know of any other way to treat boards without using chemicals that could leach into the garden itself. any help, advice or Ideas are welcome and very appreciated.

Thank You all for taking the time to read my first post and Happy Thanksgiving!

Todd

 

[Sean Regan]

Hi and welcome.

Rot gets to wood...eventually, any contact with damp earth will do the damage over time.

I've several wood constructions in my small garden, two pergolas and two small buildings all made from soft wood, though some of it tanilised. The two buildings are over thirty years old. The pergolas were replaced about fifteen years ago.

Here's a tour.

All get regular coats of Dulux Trade exterior Woodsheen, wood stain, at £50 ($65) for a 2.5 ltr can, it isn't cheap. But it forms a polymer skin over the wood so become impervious to water unless damaged.


I hate the sight of anything plastic.

The closest I get to raised beds are these two troughs.

They're probably some sort of softwood, which I painted with the same paint. I also knocked out the plywood base and replaced it with two 2" X 2" rails.
The hebes are each in plastic pots sitting in plastic saucers. So there's no earth touching any wood anywhere. They also have a couple of pieces of 4" X 2" under the rails to keep the box off the ground.

The plastic pots can't be seen from a distance. I've had them a few years now.

I don't know if it's any help, but whatever wood you choose, if you can keep the earth off the wood you've a much better chance of your beds being durable.

 

[DirtMechanic]

A plastic liner or painted membrane would work. I used this on the plywood roof of a doghouse. It got a coat of paint and never failed. Regular plywood will fly to pieces over time outside. The bottom of the doghouse rotted. It is used to seal up showers before tiling, so I had some leftover from a bathroom remodel and it lasted an unexpectedly long time outdoors. It makes a very thick, very tough plastic membrane when painted on.

 

[toddt]

Thank You for the replies. Any thoughts on the use of chemicals, paints, or sealants on the inside of the material that will be in direct contact with the soil and potting mixes? I know the tractor supply one that I bought was painted. I came across an argument/discussion a while back online about using pressure treated materials and it seems that a lot of people are very opposed to it. not sure if there would be the same concern for paints and sealants. Not looking to start a huge debate either. Just trying to figure out what is the best route to go here.

 

[DirtMechanic]

If you want to over think it, go ahead and jump fully into the details. One detail about treated wood is that by getting away from arsenic and using copper, they figure they are safer. Well let me tell you from experience the wood rots now, and copper is used as a organic fungicide that you spray directly upon your plants. Personally I think boric acid would serve better but it is a problem for plants in any real quantity.

 

[toddt]

Thank You for your thoughts and reply.

 

[SQWIB]

PT is fine.

Or checkout TSC, they have quite a few different configurations.

 

[toddt]

Ok, first of all, those planters you built look pretty awesome.

I saw those feeders at tractor supply and did consider them. They just aren't the look we are going for.

I think I may go with PT. I have a feeling we breathe in far more toxins than some lumber may ever leach into soil. If the new pt chemicals are even toxic to begin with. Thanks again and be well.

 

[SQWIB]

If I was younger and wanted the beds to outlive me, I woud have built the beds around the galvanized metal, more expensive but would last a long time.