Mulch for the vegetable garden

New gardeners can be confused by too many mulch choices.

Straw mulch
Photo credit: meganpru at flickr.com

Vegetable gardening is becoming trendy again. There have always been the gardeners who appreciated being able to harvest fresh vegetables right from their own backyard. They have now been joined by new gardeners who want to grow fresh produce and learn every step it takes to bring it from the garden row to their dinner plate. Two questions that are often asked by new gardeners are “Why should I mulch?” and “What kind of mulch should I use?”

Mulching serves several purposes. It prevents weed seeds from germinating because of lack of light, and keeps soil cooler so most vegetables grow better. It prevents top evaporation so it is not necessary to water as often. Mulch prevents soil particles from bouncing and sticking to vegetables or fruit and keeps the produce cleaner. It may also be more comfortable to kneel on when weeding or picking.

The first choice is no mulch at all. But, soil can become compact, weeds grow and soil heats and dries rapidly. A process called dust mulching can be used when no mulch is wanted. This involves using either a hoe or a tiller that has a depth gauge to determine a 1-inch tilling depth. If you are hoeing, work backwards so you do not leave footprints. Weeds will grow rapidly as soon as the soil is compacted by walking on it or when it rains. Tillers that are self-propelled are ideal for dust mulching. Soil at the top is loose and dry and the soil below stays damp.

Below are a number of mulches that gardeners have used. The preferred category is biodegradable mulch. Adding organic matter is always good. You want to be able to chop up and till the mulch back into the soil as soon as the garden is done. Wheat or oat straw is usually clean and does not bring weed seeds to the garden like hay does. If using grass clippings, be sure six weeks have passed since weed killers were used on the lawn. Essentially, both weeds and vegetables are broad-leafed plants and could be affected by the herbicide. It is best to use dry grass clippings because they do not form a mat like fresh ones do.

Any of the mulches that are slow to break down or permanent are difficult to use in a vegetable garden because they get mixed into the soil and have to be sorted out when planting next season. Seeds grow poorly on top of pieces of wood or corncobs.

Types of mulches used by gardeners

Biodegradable mulch
(one season)

Slow to break down (could be years)

It’s never ‘gonna go away
(permanent unless removed)

Straw
Leaves
Grass clippings
Shredded newspaper
Whole newspaper
Cocoa bean hulls
Pine straw
Hay
Cardboard

Woodchips
Bark
Shredded wood
Corncobs

Rocks
Carpet strips
Plastic
Landscape fabric
Shingles/tarpaper