home garden

National Composting Conference

Composting

By Jim Hole

In September 2000, Edmonton hosted the 10th annual National Composting Conference. The focal point of the conference was the Jekyll and Hyde nature of compost. So, how do we turn liabilities like dead plant matter, lumber mill waste, and manure into a manageable resource?

Climbing the C:N Tower

Delegates at the conference noted that any material to be broken down must be organic; in other words, it must contain the element carbon. Fortunately, all terrestrial life is made with carbon building blocks, so this is never a limiting factor. What can limit your compostable materials, though, is nitrogen, the same nutrient found in many fertilizers. The carbon:nitrogen, or C:N, ratio was frequently discussed at the conference. Unless the C:N ratio is within the correct range, the breakdown of organic matter comes to a virtual standstill. Ideally, the waste that you are breaking down should have a C:N ratio of 30:1.

Sawdust—a waste product many have tried to compost with frustrating results—has a C:N ratio of 400:1. Sawdust's very low nitrogen count explains why it takes so painfully long to decompose. Grass clippings, on the other hand, have tons of nitrogen, and if added to a pile of sawdust they can help to strike the right balance between carbon and nitrogen.

Moisture Balance

Finding the correct moisture balance is the second big issue in composting. In one presentation, researchers from the Agriculture and Agri-Food Canada Research Centre in Lethbridge explained the difficulty they faced with composting feed lot manure. Initially, the moisture level in manure is excessive, but after a few short weeks of hot, dry winds, the composting manure becomes too dry for proper decomposition. Whether the compost is too wet or too dry, the breakdown process slows down to a crawl. In back yards, the scale is smaller but the problem can often be the same. Ideally, compost should feel like a moist sponge that's just been wrung out. If your compost is too dry, simply water it. If too wet, turn it with a pitchfork to expose as much of the material as possible to the air.

Air

Finally, remember that compost should never be allowed to get too heavy or dense; this, too, will hinder decomposition. Regular aeration of the compost pile is critical, and easily achieved by turning the pile with a pitchfork once a week.

Training Shrubs to Single-Stem Tree Form

Training Shrubs to Single-Stem Tree Form

Looking to add a distinctive feature to your yard? Try training shrubs into a long, branchless central stem topped with a full head of foliage. With quality plants, the right technique and patience, you can transform your favourite shrubs into dynamic tree silhouettes. Here’s how.

  • Start with a high-quality shrub in a one or two gallon pot and plant as you would any shrub.

  • Examine the shrub and select the largest, healthiest stem. This will become the ‘trunk’ of your tree-form shrub. Prune off most of the other stems, leaving some extra branches untouched for the moment. The extra foliage of these branches will give the plant the energy it needs to grow.

  • Maintain the tree form by pruning off new side shoots so that all of the plant’s energy goes into the remaining stem.

  • Stake and rod the stem to keep it upright. The rod and stakes should remain in place until the selected stem is able to support the weight of the plant.

  • Once the shrub reaches the desired height (1.2 m of clear stem is a good guideline), clip the top to force buds out, and remove any buds on the stem. This is also the time to remove those extra branches you left on the stem for plant growth. Treat like a normal shrub to produce a nice round head.

  • The shrub will continue to produce shoots in unwanted areas. Remove these shoots to maintain the tree form.

Make sure your expectations are realistic—training will not transform a 2-m tall shrub
into a 4-m tall tree, though your shrub may grow a little taller than usual because the
plant’s energy has been redirected to a single, central stem.

You can train almost any shrub, but here are a few suggestions to get you started.

Amur maple
Russian olive
Lilac
Evans cherry
Ninebark
Potentilla
Dogwood
Hardy roses
Hydrangea
 

Multi-Stemmed Tree Forms

Many large shrubs can be trained to multi-stemmed tree forms of three, five or seven
stems. Russian olive and amur maple look beautiful when trained to these forms.

Buying Tree-Form Shrubs

If you like the look but don’t feel like doing the work, you can buy mature shrubs in tree
form. Some of these shrubs are trained to tree form (dogwood, potentilla, ninebark, hydrangea), while others are created by grafting a shrub such as lilac or caragana to a
compatible rootstock. Note, however, that grafted tree-form shrubs are generally easier
to maintain than trained tree-form shrubs, as the rootstocks are chosen both for height
and their tendency to avoid creating side shoots. Grafted tree form shrubs come in a
variety of heights. In some cases, the central stem may be a metre tall, in others only
half that. It all depends on what the grower has chosen.