Tag Archives: raised bed gardening

Raised Bed Gardening


artistic design garden bedWith spring now upon us, I’ve been asked by several of my clients about the viability of raised bed gardens for growing vegetables and, in one instance, flowers for cutting. They wanted to know how practical they were, the cost involved and if they were really worth the bother? My answer is quite simple; if you’re serious about raising vegetables or creating a cutting garden, constructing a raised bed make perfect sense.

A raised bed makes gardening easy. Filled with the appropriate soil mix, they provide the excellent drainage needed to grow picture-perfect vegetables and flowers.


For many gardeners, not having to bend or kneel to weed and harvest crops is a real bonus. And if your objective is to grow tomatoes, building a raised bed against a sunny wall or fence means that heat-loving crops, such as tomatoes, will thrive and require less watering than those grown in pots.

Here is Wikipedia’s take on Raised Bed Gardening


Raised beds lend themselves to the development of complex agriculture systems that utilize many of the principles and methods of permaculture (agricultural ecosystems intended to be sustainable and self-sufficient). They can be used effectively to control erosion and recycle and conserve water and nutrients by building them along contour lines on slopes.

This also makes more space available for intensive crop production. They can be created over large areas using any number of commonly available materials and efficiently maintained, planted and harvested using hand tools.

Materials and Construction

RaisedGardenBeds Illustration

Vegetable garden bed construction materials should be chosen carefully. Some concerns exist regarding the use of pressure-treated timber. Pine that was treated using chromated copper arsenate or CCA, a toxic chemical mix for preserving timber that may leach chemicals into the soil which in turn can be drawn up into the plants, is a concern for vegetable growers, where part or all of the plant is eaten.

If using timber to raise the garden bed, ensure that it is an untreated hardwood to prevent the risk of chemicals leaching into the soil. A common approach is to use timber sleepers joined with steel rods to hold them together.

Building Raised Garden Bed

Another approach is to use concrete blocks, although less aesthetically pleasing, they are inexpensive to source and easy to use.

On the market are also prefab raised garden bed solutions which are made from long lasting polyethylene that is UV stabilized and food grade so it will not leach undesirable chemicals into the soil or deteriorate in the elements. A double skinned wall provides an air pocket of insulation that minimizes the temperature fluctuations and drying out of the soil in the garden bed.

Sometimes raised bed gardens are covered with clear plastic to protect the crops from wind and strong rains.

In addition to wood, stone, concrete, cinder block, galvanized culverts, stock tanks, Cor-Ten steel and pre-manufactured raised bed products, there is a new fun product that not only provides an interesting solution to creating a raised bed, it helps deal with the problem of what to do with plastic by creating a Lego-like modular system of interlocking blocks for easy assembly

togetherFarm-box-edge Check out this simple but ingenious design solution at Urban Gardens. And here are 8 materials for raised bed gardens described in an excellent article in Houzz.


Dangers Of Organic Gardening!

Veggies On The Run

As Spring is here and those who like to grow their own are preparing to do so, I had a question from a client about planting vegetables in raised beds. It appears she, like a good Girl Scout, did everything by the book: organic potting soil and fertilizer and a drip system for watering.  Yet her veggies grew with yellow leaves.

While it’s not as bad as having slugs in your garden it is annoying. So what’s a gardener to do?

Yellow leaves on vegetables usually mean they’re not getting enough nitrogen. The problem may well be that you filled your raised beds with “organic” potting soil and not a good quality amended top soil.

It’s come to my attention that some manufacturers of bagged organic soil are using wood products that have not had adequate nitrogen added to them in order to make them rot. Since they’re  “organic”, they can’t add sulfate of ammonia, a cheap source of nitrogen, to the shavings because sulfate of ammonia is not a natural source of nitrogen.

Raised Bed

Raw, un-rotted, un-nitrolized wood shavings will rob nitrogen from the soil in order to rot and this action turns veggies yellow from lack of nitrogen. To correct the problem you will need to add more nitrogen.

Blood meal is a strong organic source of nitrogen, but many gardeners don’t want to use it because it comes from feed lots. Alfalfa meal is also good but alfalfa tea gives quicker results. (There is a recipe for alfalfa tea on page 119 of “Pat Welsh’s Southern California Organic Gardening, Month by Month.”) The good news is that your problem will eventually clear up. Once the raw shavings in the soil have fully rotted, they will release the previously stolen nitrogen into the soil and plants will get a huge boost.

If you filled your raised bed with potting soil instead of topsoil you might consider adding  top soil the next time the season changes and you plant new crops. Because, as the wood products in the potting soil rot, they decrease the volume of soil in your raised bed.