Hi all,

We live in the north/central valley (CA - relatively mild climate) and are wanting to build raised garden boxes for vegitables. Something like 2 or 3 feet wide by up to 8 feet long and 12 to 16 inches deep. We want to 'raise' these boxes about 6 inches off of the ground...probably using 4x4 'legs.' We're thinking the sides and bottom would be used with either 2x6's or 2x8's.

With that in mind, we are thinking of going with Douglas Fir and then treating it with linseed oil. However, 1) we're not too sure how long D/F treated with linseed oil might last in our climate of some rainy springs/falls and airid hot summers and cool winters (w/o snow or much rain) and 2) should raw or boiled linseed oil be used?

Or.....

Should we just 'bite the bullet' so to speak and buy the more expensive cedar or redwood because it will last much longer? If so, which would be better for such raised vegi gardens?

Thank you much for looking and for any help/experience you could offer.

 

Use pressure treated wood. Some may say don't do it but they are idealistic; not realistic. “Stack” two or more 2x 8 or 2 x 12 on edge. Your beds will be benefit from the added depth.

 

Whats his name on "ask this old house" likes cedar wood for these and other planter boxes, slow to rot and bugs don't like it. Why raise it off the ground? the soil will dry out real quick. Google - square foot gardening

 

Thanks for the reply's folks.

Raised because the only location we have for these often times has some runoff water standing during the spring/fall months. Not always, but enough times and for long enough we don't want the plants damaged. Also, because they will go in an area that has 3/4" 'salt n pepper' landscape rock, not directly on the dirt. I was planning to use a drip/micro spray system on automatic timer...probably 3 or 4 times a week (if necessary).

 

Treated lumber is probably the most inexpensive lumber choice and will probably last the longest. If you are concerned about the preservatives leeching into the soil you can line the box with heavy duty plastic or galvanized steel to prevent the soil from coming into direct contact with the treated wood.

 

Thanks much for the reply!

I'll be going to the h/w store sometime this week to check on prices, but I suspect that Doug Fir + Linseed oil may be cheaper than Treated lumber + plastic (or galv. steel). Also, I know I'll be able to find D/F in 2x8 (more options), whereas I'm not too sure I can find that dimensions in treated lumber.

Just curious if anyone has used the D/F + Linseed oil scenario...and how it's held up.

 

rxsid...did you just get the new Pop Mechanics magazine? Lol They have a several page article on building raised planters.

 

It's my understanding that there is more copper in the newer pressure treated woods. That should be of concern if edibles are going to be grown as copper can be toxic if too much is ingested. Plants will take up leaching copper. Be sure to scroll down to read about borate treated lumber.
http://www.taunton.com/finehomebuild...ood-decks.aspx

Newt

 

Just semi-quoting from the PM article I mentioned earlier...

"The EPA considers ACQ treated wood to be safe for food crops, but if you use this PT wood, you may want to line the bed interior with landscape fabric to prevent soil contact."

It does have copper...but at least it doesn't have arsenic like the old stuff.

 

Thanks Gunguy45 for the reply and the info!

Might you have a link to this article you mentioned? I've looked on their site ( Popular Mechanics) , but can't find any reference to this article in the current issue.

Also, their statement is a bit mixed in that they (EPA) consider ACQ was being safe for food...but then go on to say that one may want to line it with landscape fabric to prevent soil contact. If it's not harmful, why line it? Seems like an unnecessary expense.

In any event, I don't plan to use any treated wood, as I'm thinking that is an unnecessary expense as well being that Douglas Fir is cheaper. And the cost of linseed oil vs landscape fabric is probably a wash...or close to it.

If you have a link to that article, I would be much obliged!

 

I don't think they put the latest issue articles on the website...its on pg 95 of the April issue.

I really think the editors/writers just included the statement for people that are real hesitant about possible chemical absorption.

One thing to remember, fir that is in contact with soil and moisture just really won't last. The linseed oil may help, but you'll still have mold and insect damage to contend with. Don't know whether you have carpenter ants, termites, and carpenter bees where you are, but back in VA using regular "whitewood" without some sort of exterior preservative (like for a deck) would have been a rebuild it every year proposition. And don't forget squirrels chewing and digging.

 

What about using something like Trex or one of those composite woods?

Newt

 

I am not sure how long linseed oil and spruce would last. Linseed oil will help, but the wood can still rot and insects will still eat it. I am sure you could get several years use but I would not expect it to last long term (10 or 15 years).

Last year I did a big, formal raised bed garden at our house. I considered using Trex or other synthetic woods but they are very expensive and not "structural" so I would still have to build a support frame to support the Trex.

I have a manufacturing business and was able to get 1/4" thick sheets of plastic. I built a wooden frame of pressure treated lumber and lined them with the plastic so the soil never touches wood.

 

Hi all,

Thanks for all the reply's. I do appreciate them.

We have no 'varmint's where we are, and there are currently no termites either. Only problem really is lots of little black ants.

I looked at the trex and that stuff was simply way too expensive and quit frankly wasn't 'structural' enough, IMO. I could get sanded prime cut cedar or redwood for about a 1/3 the cost. There was some 1" x 12" x 8' redwood 'kicker board' that is often used for yard fences. It was about $11 a piece, but after some thought, I determined that it was probably too thin being only 1 inch think for 8 foot + beds. Would probably need bracing and occasional repairs with the pressure of the soil over the years. Since I'm planing on, at least, 7 raised beds of 2' x 8' x 10", the redwood in the 2" x 10" x 8' dimension was going to add up to too much for us for this project.

After looking at the prices of the various options, I'm going to go with Douglas Fir and simply line the interior (where the soil would be) with 6 mil plastic. I'm going with 6 mil, instead of 4 mil, because the 6 states on the package that it can be used as a moisture/vapor barrier whereas the 4 mil doesn't. I know, the 4 mil would probably be fine, but the difference in cost for the project is around $8, so I'm just going to go with the 6 mil. I plan to either paint the exposed exterior, or put a preservative on it.

Can anyone recommend a decent, no/low VOX wood preservative for the exterior facing portion of the boards?

Thanks!

 

Nice work by the way! Have any pictures of the 'underside?' The reason I ask is that it appears those beds are suspended (i.e. not resting on the ground). How deep are they?

 

Sorry it took so long for me to reply. I totally forgot about this thread. I'll take some pictures from the other side and get them uploaded. In the mean time...

There is considerable elevation change where the garden is located. The top of each bed is level so when watering the water would soak in instead of running off.

So while the tops of the beds are level they are burried to varying depts. One end of the bed may be sitting on the surface while the other end 8ft away is burried a foot into the ground.

About 2/3 of the beds are 16" deep while the others are 24". The plastic came in 4' x 8' sheets so that minimized waste. The bottom of the beds are open for drainage.

We have a considerable problem with animals like: mice, opossum, groundhog, snakes, deer, moles... The lowest 24" of fencing is 1/2" mesh hardware cloth to keep out mice and snakes. Coupled with the height of the beds this creates a solid barrier for about 12-18" then the 1/2" mesh and then above that is wider opening fencing which tops out at about 6ft. The fencing serves double duty. It keeps animals out and is a great trellis for tying up beans.

The interior of the garden area is filled with white pea gravel choosen because it's round shape is easy on bare feet and the white color stays cool in the summer sun. Also a benefit for bare feet. A old cast iron sink is used as a potting bench (you can see the back of it in the first photo).

 

Here is a picture outside the garden looking in.

 

Good work!

I'm building omething similar, and hope to start posting photos, progress, etc, soon.

Quietman

P.S. Haven't forgot about the R/C plane either, progress has been slow as I prepare for spring.

 

i have twelve cedar "whisky kegs" that i garden in. the did well except for the bottom edges on a couple. i've since set them on trex type risers and there is no deterioration.

 

Bought a Raised Garden Bed to plant vegetables.

We have never had one before.

My question is, Even though the wood is made of Cedar, would it still be a good idea to put some kind of stain on it to preserve the wood? We live in northern Vermont.

I also read somewhere, that it was a good idea to put gravel on the ground were the boards lay on the ground. Would that be a good idea also, or is it overkill?

Thank you to all.

 

Cedar is naturally rot resistant. I would leave the wood bare, with no sealer. That way you do not have to worry about any chemicals from the sealer/stain getting into the soil and eventually your food.

I would not bother with gravel under the boards. It would not hurt, but it's extra work and the whole inside side of the boards will be touching soil so it will not dramatically increase their lifespan.

Find a level spot. Dig out the sod inside the garden area. Plop down your cedar raised bed frame. Fill it with good soil and start planting.