Root proof raised redwood garden beds

Redwood planter boxes with root protection

Last summer Stephan and I were tasked with designing and constructing some raised garden beds in Los Gatos. There were existing beds on the property that had become overrun with roots from a large oak tree in the back yard, rendering them useless and causing the old beds to break apart. Tree roots have a way of working their way into pretty much everything and can certainly become an issue in the garden as well, especially when they can find an area that is irrigated during the summer months.

2x6 frames before final assembly

Keeping this in mind, we had to come up with a design that would prevent root intrusion into the raised beds, which is impossible if the bed has any openings in the bottom. The standard procedure of covering the bottom with gopher wire wasn't going to work for this application.

In order to alleviate these concerns and to ensure the beds will last for many years to come, we enclosed to bottom of the beds with redwood 2x6 decking, turning them into large planter boxes, leaving a small space for expansion between each board, which is a must for any outdoor construction project using wood.

Assembled frames on pickup

There was concern over having adequate drainage into the existing soil with the bottoms in place as well so we opted to elevate each box using pressure-treated lumber. To prevent the boxes from sinking into the mud the weight was distributed onto 5/8" pressure treated plywood below. The use of pressure treated material normally isn't acceptable for use in vegetable beds (see linked post) but is fine here because it does not come in contact with the soil inside the boxes. The end result was four extremely durable large redwood planter boxes on bases that will last for decades.

These boxes are made entirely from construction-heart grade redwood 2x6 decking, which gives them a lot of flair. The top rails provide a working surface or a seat for those tending the garden and also add some strength to the boxes. Making all of the cuts and assembling all of the pieces takes a lot more time and skill, but the end result is well worth the extra labor. If you want to turn heads with your new raised beds or planter boxes, this is the way to go.

Robert carefully screws the bottom boards on

Inside view of the box

Instructional video- raised redwood beds

Here's a great video on how to construct a very basic redwood garden bed, produced by Bruce Bauer Lumber and Supply in Mountain View, CA. I like the simple design and ease of construction:

This type of bed utilizes 2x12s, has only a few pieces, and will last a very long time. 

The GRK screws used are expensive and probably overkill for this little project, but I find they are a huge time-saver for larger projects or if you are building multiple beds. I'll talk about fasteners at a later time

These guys use galvanized wire for the bottom of the bed. This is perfectly acceptable to keep out rodents, but stainless steel gopher wire is a better choice as it will last longer in the ground. You can order online here or if you're in the Santa Cruz area Mountain Feed in Ben Lomond carries it as well.

It's also a good idea to use some 1/4"  redwood lath strips screwed along the bottom perimeter to ensure critters can't push their way in through the gaps left between staples. Plus, working with those fencing staples can be a pain in the ass for those who don't have a steady hand with a hammer.

I will post my own instructional video and make a page the next time I build some beds.

Is it ok to use pressure-treated lumber on raised garden beds?

Photo by Rusty Clark. Creative Common license.

Pressure-treated lumber is extremely popular for outdoor applications. It lasts for decades without rotting and can be placed directly in contact with the ground. A frequent question that arises is whether or not it is acceptable to construct raised vegetable garden beds out of this material.

Before 2003, most treated lumber contained high levels or arsenic, which was proven by the EPA to slowly diffuse into the surrounding soil making it toxic. Since then alternative compounds have been used and treated lumber is supposedly safer.

There is debate as to whether or not the chemicals in the "new" treated wood such as copper derivatives can leach into the soil and end up on the dinner table. Studies have been conducted with mixed results on this matter.

Personally, I would never use treated lumber to construct garden beds. Redwood looks much nicer and also has similar longevity. The cost is only slightly higher, and you don't have to worry about the risk of consuming the fungicides in treated lumber that may end up in the soil. It should be noted that in many regions the use of treated lumber is banned for those seeking organic certifications.

Why risk your health for a product that doesn't look as nice? There are viable alternatives to redwood which I will cover later, however using treated lumber on vegetable beds is a bad idea in my opinion.

5 Reasons why raised redwood beds will improve your garden

Custom built redwood beds in a bird-proof enclosure. A beautiful addition to any yard.

The use of raised beds is an excellent way to create a garden that thrives just about anywhere, and is growing in popularity as we strive to maximize the quality and yield of our vegetables and flowers, often in rather tight spaces. Raised beds are superior to traditional in-ground ones for the following reasons.

1.) Less back pain. Anyone who has spent countless hours bent over in the garden pulling weeds has probably experienced a sore back. Raised beds are elevated so that they are easier to reach and work on without putting unnecessary strain on your body.

2.) Improved drainage-- In areas where the soil has a slower percolation rate raised beds are often the only reliable way to garden. Healthy root systems need to dry out from time to time and if they are constantly waterlogged your plants will not do well.

3.) Raised beds warm up faster in the spring-- For those in cooler climates, plants will get a jump start in the morning over those in the ground.

4.) Pest control-- Using raised beds lined with gopher wire will eliminate the headache caused by gophers killing off your prized plants by denying access to them. Also, it is easier to control insect populations in the confined environment that they provide so there are less issues with pests such as aphids and spider mites.

5.) Appearance-- Raised beds built from redwood will add natural beauty to your yard and can be very pleasing to the eye. Since they can be built in just about any style you can dream up and construct the perfect addition to your yard or patio.

So what are you waiting for? It's time to come up with a design.