According to Wikipedia, a mulch is a layer of material applied to the surface of an area of soil.
Its purpose can be any or all of the following: to conserve moisture, improve the soil, reduce weed growth, keep the soil temperature consistent and be visually appealing.
Mulch is spread over the earth, providing a barrier between the earth and the sun.
It stops evaporation and, as a result, keeps the soil moist.
In hot dry climates, a layer of mulch makes the difference if a plant lives or dies.
Where moisture is plentiful and the heat of the sun is limited, mulch can retain too much moisture, causing the soil to be too wet and cold.
Plants grow slower when they have cold, wet feet; bulbs and roots can rot.
Soil will be improved if organic mulch that breaks down quickly is spread over the soil.
The more earth-like the mulch, the quicker worms can incorporate it into the soil.
Compost, well-rotted manure and peatmoss will become part of the soil within a season.
When grass or straw is used, pieces of the original product will still be visible next season.
Wood chips will break down but it will take much longer to become soil.
They make a good topping for ornamental beds but not for a vegetable garden.
For best results, the soil should be free of perennial weeds (dandelions, grass, thistles, etc.) before mulch is used.
If these weeds, exist they will grow through the mulch unless an impenetrable layer is placed between the soil and sun.
Plastic, cardboard or a number of sheets of newspaper under a thick layer of mulch will usually block out all sunlight, killing most weeds.
Jute-based carpet and sun-resistant plastic/rubber strips eliminate weeding between rows in the vegetable garden but they are not desirable in ornamental gardens.
Landscape fabric has holes that allow the exchange of air, moisture and sunlight.
If weeds are growing when the fabric is put in place, they will grow though the fabric. Before putting down landscape fabric, make sure the soil is weed free.
In climates where the sun bakes the soil and evaporates all the moisture, it is important to mulch the soil during the summer to keep the soil cool and moist, allowing plants to flourish.
In other areas where moisture is plentiful and the soil does not need to be watered more than once a week, mulching the soil can result in slower growth due to a cold soil.
Areas that have poor snow cover and fluctuating temperatures during the winter months benefit from a fall mulch that keeps the soil a uniform temperature regardless of the air temperature.
All gardens, including vegetable gardens, should be visually appealing. Use mulch that is attractive.
The decorative mulch most commonly used in ornamental gardens in Central Alberta are wood chips and rock.
A thick layer of woodchips will keep weed growth to a minimum. Wood chips break down over time and will need to be replenished. As the chips decompose, they use nitrogen from the soil and can leave little for the plants in the bed.
Plants that have yellow leaves with green veins will benefit from a nitrogen-rich fertilizer.
Rock mulch comes in various colours and sizes.
It is heavy to move but lasts forever.
Rock holds the heat, which can be beneficial in the fall and spring but a detriment in the hot months.
What gardener does not want to reduce the amount of weeding that is done in the garden?
If applied and maintained, mulches will reduce garden maintenance.
But mulches are not maintenance free — they still need to be weeded but fewer weeds will be present.
Linda Tomlinson is a horticulturalist lives near Rocky Mountain House. She can be reached at www.igardencanada.com or your_garden@hotmail.com.