Jan 202012
 
Raised beds


By Avis Licht

Raised beds have many advantages.  They  provide better drainage,  better access, better plant growth and reduced soil compaction.  There are many ways to build a raised bed.  Let’s  see what would be best for your garden.

Raised beds

Double dug beds are raised and need no edging

The Simplest Raised Beds

These don’t need any built up edge, they only need to be double dug.

This act of digging and moving the soil aerates it and raises it up. Here’s a more detailed explanation.  This is especially effective when opening up the soil for the first time.    By creating “beds” instead of rows, you leave paths for walking and you never step on the bed.  This prevents compaction and allows water and air to penetrate the soil, making for healthier roots. It also lets you plant in a more intensive manner.

Double digging is hard work, but doesn’t need to be done every season. In another post I’ll show you the many reasons for using this method, and different ways you can incorporate  fertility.

Stone for raised beds

Raised beds using stone for both low and tall walls

Stone Raised Beds

Stone lasts forever, and looks beautiful.  It is also easy to create  curving lines in the garden.

As you can see in the photo above, you can use stone to edge your beds, it defines the line and creates a clear path.You can use it to build a wall, which is especially effective on a slope. In this garden, the curved bed was built to 2 ft high, which helps the owner who has back issues.  We  used the opportunity of the height of the bed to bring in some good organic topsoil.

If you bring in soil, be sure to loosen up the bottom of the bed.  It doesn’t help to bring in good topsoil if you don’t have good drainage.

Cost is a factor in deciding whether or not to use stone.  It can be expensive if you have to buy it, and  it takes time to install it.

buildiing curves with stone is easy

This curved bed looks good even when the garden is dormant

Wood Raised Beds

Wood is commonly used for building raised beds in the vegetable garden. Use recycled wood if possible.  Buying redwood or cedar has many implications to the environment.  If you are only raising the beds a few inches, I don’t think wood is worth the effort or the cost.

If you do use wood, be sure not to use pressure treated wood. This includes old railroad ties. The chemicals in this wood are hazardous to your health and the environment.  This article covers the pros and cons of using wood.

Bamboo raised bed

Bamboo or willow can make a great raised bed, especially if you are growing it yourself

You can even find recycled plastic for raised beds. Kits with all the materials you need can make the project simple.  Gardener’s Supply carries all kinds of raised bed kits.

 

Raised beds with stone from the site

The raised bed just planted

 

 

 

When deciding whether to use raised beds in your edible landscape consider your site, soil, resources and aesthetics.

 

 

 

Vegetable garden

The raised bed a year later-- vegetables and flowers

Nov 082011
 
Low retaining walls can help prevent erosion

Low stone retaining walls keep soil from falling into the driveway

Erosion of  hillsides can range from minor movement that is easy to repair, to major and dangerous situations.

Caveat! Caveat! Caveat!

If you think you have a major problem, please refer to a professional soil engineer or contractor to help you.  In this post, I am only going to address simple  erosion problems.

 

 

 

 

Building low stone retaining walls can be simple and effective for keeping  hillsides from eroding.

These walls were built without mortar in  a method called drystack.  Only soil was used to hold them in place.  Cutting back into the hillside, laying the stone, back filling with soil and then planting keeps the base of the wall stable.

Loose soil will collect in the beds at the bottom of the hill.

Vegetated swale

The swale is covered with a biodegradable erosion blanket and sowed with clover and wildflower seeds

 

When assessing your slope for erosion problems look for these signs:

  • Channels already formed in the hillside from runoff
  • Bare soil that is exposed to  rain or water runoff
  • Downspouts or other water sources

Ways to minimize water damage include:

  • Create swales that are on the contour of your slope
  • Build retaining walls that have drainage in them
  • Sow seed and plant  fast growing shrubs to cover bare soil
  • Mulch, mulch, mulch

 

Wild strawberry and Mahonia with stone wall

At the top of the stone wall you can see the wild strawberry (click to enlarge)

In the photo above I planted a native strawberry that sends out many runners and roots into the hillside.  It will cover the hill very quickly. Other California native plants that provide excellent cover are creeping Ceanothus, trailing Manzanita and  Sonoma Sage and Coastal Sage Brush.

Planting on steep hills

Creeping ceanothus, trailing manzanita and other natives were used on this steep shady slope

Small stone walls

Small walls at the base of trees keep soil and mulch in place

The most important action for you to take in your garden is OBSERVATION.  Go out in the rain and storms and watch how the water flows.  This is the best way to learn about your garden and the only way to really know what is happening.

 

Nov 072011
 

 

Retaining walls

The hill came down, the walls went up

 

Before the rains come crashing down, take a good look around your property.  It’s especially important if you are on a hill or have slopes around you.  When water picks up speed it can really create havoc.  Take a look at this hillside. After a number of rainy days, the whole hillside came down into the driveway.  Fortunately, no person and no cars were there when the soil came down.

In an effort to get more light in the property the owners cut down many trees.  The result, light came down and so did the hillside.  They should have made sure the ground was planted and drainage was put in place.  To do it after the soil erodes is much more expensive. In addition to cutting back the hill and putting in retaining walls, we also put drain pipe behind the walls, at the top of the hill and at the bottom.  Water has to go somewhere!  Take a look.

Erosion control for steep hills may mean building retaining walls

Cement block wall at the bottom and wood retaining walls will hold back this hill

Construction of the retaining wall

Retaining wall in process

There's still too much soil, and erosion can be a problem

Cement block wall is not high enough, and soil needs to be removed

After the walls are built, it is important to plant for soil coverage.  I use seeds for immediate coverage and plants for long term coverage.  At the top of the hill we put in a swale to redirect the water away from the main walls. We covered it with erosion control blankets.  They are both 100% biodegradable, but they are slightly different. One is thicker and made of coconut fiber and the other has straw put between cotton netting. The thick mat is better for stronger erosion control and the straw allows better germination of seeds.

Two types of erosion control blankets - coconut and straw

The blanket on the left has straw and the blanket on the right is coconut fiber.

Swale

A long swale covered with netting and also planted with seed

For quick germination I used rye grass, Dutch white clover, vetch and California wildflower mix, with extra California poppies. We were lucky with early October rains that helped with excellent germination.  If you don’t expect rain, you should water the seeds to take advantage of warmer weather in the early Fall.  Once the winter rains come it gets too cold for most seeds to germinate.

Erosion control seed mix

Rye grass, Dutch white clover, Vetch and Wildflowers

Seeds germinating through straw mulch

Straw mulch holds the soil in place and protects the seed

 

Tomorrow I’ll talk about other simple erosion control  methods.

Curving path on steep hill

Using plants and curving path for hillside erosion control

 

 

 

 

 

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