Bob DluzenThe Detroit News
One of the best natural mulches for vegetable gardens is straw.
Straw is a by product of grain crops and is made up of the dead stalks and leaves left behind after farmers harvest the grain. It can be from any grain such as oats, barley, wheat or other similar crops.
Corn however, does not produce straw, the stalks from corn are much larger and coarser. Dead corn stalks and leaves are known as “stover” and is not used for garden mulch.
Straw is sometimes mistakenly called hay by inexperienced gardeners. Hay consists of the live parts of growing plants that are cut and left to dry in the field. It is usually green in color and comes in the same size and shape as straw bales. To confuse the issue even more, straw is the material used for hayrides!
Wheat straw is the most common type of straw we have available to us because it is the most commonly grown grain in this area.
Most gardeners who use straw mulch used it for controlling weeds. With a deep enough application of straw most weeds can be prevented from growing. If you plan to use straw as your sole weed control, use at least six inches of fluffed up straw. That is enough to inhibit most common garden weeds. Anything less than that will be counter productive and can actually encourage weed growth and will make hoeing or weeding much more difficult.
The exception to the six inch guideline is when a weed barrier of some sort is first placed on the soil before straw is applied. Newspapers used to be the traditional material but since those are getting hard to find, cardboard is now used.
If you decide to use cardboard, remember to remove all of the tape from shipping boxes before laying it done otherwise you’ll be finding tape in your garden soil for years.
Three inches of straw over a cardboard layer works fine. It holds the cardboard in place and makes the mulched area look much more attractive than a bunch of broken down boxes laying in the garden.
Always do a thorough hoeing or weeding before putting down your straw otherwise some weed seedlings will have enough strength to grow right through the straw layer.
Perennial weeds such as quackgrass, can easily grow through straw. If your garden area has a problem with perennial weeds, you must put down a weed barrier in order for straw to be effective.
I like to mulch the entire garden area when using straw including around plants and in between rows. Doing it that way provides a nice surface to walk on and work from.
Mulching with straw will inhibit the spread of garden plant diseases. Many of these diseases are present in the soil as spores. When it rains, the raindrops hit the soil and splashes spores up onto the plant leaves which then infects the plant. Using a layer of straw isolates the soil so spores cannot be splashed up.
Straw makes an attractive mulch in the vegetable garden, but I think it looks out of place in landscapes and flower gardens.
A normal sized bale of straw will cover about a ten by ten foot area.
The best wheat straw has a bright, uniform golden color. Areas of brown stems indicates weed stems are present which may contain weed seeds. If you have a choice, pick another bale.
Old straw and spoiled straw loses its golden color after a while. Also there may be deteriorated areas that were exposed to moisture in storage. For the most part that is no problem and the straw is still good to use for mulch. It’s going to be exposed to moisture in the garden anyway and will begin decomposing soon after application.
Some gardeners prefer using decomposing straw in parts of their gardens claiming plants nutrients are released quicker.
Straw is particularly good as mulch for potatoes. It’s common practice to hill up soil around potato plants to keep the tubers from being exposed to the sun and turning green. A good layer of straw serves the same purpose plus it makes it easier to harvest the potatoes.
One disadvantage to straw is when it is first applied, it can be picked up by the wind and land in the lawn. That quickly stops once the straw gets rained on and settles down. So you may want to wet down your straw after application to help keep it in place.
An additional benefit to using straw is it keeps water from evaporating from the soil reducing the need for irrigation.
If used consistently and left in place from one year to the next, the bottom layer of decomposing straw will build up garden soil by adding valuable humus. Helpful soil microorganisms and earthworms thrive in in that kind of environment making it a win-win for you. You’ll have very few weeds while feeding your garden soil at the same time -- it's everything a gardener could want.
