A post about mulch!

Mulch is a favorite topic of mine.  It does so many things for a garden - it really is a cure all for most of what ails us!  Here is a short list of the benefits of mulch in a garden:

• Reduces weeding by smothering weed seedlings
• Reduces watering by shading the soil to reduce evaporation
• Keeps soil cooler in spring and warmer in fall
• Adds organic matter to the soil as it breaks down
• Increases soil life by providing a perfect environment for microbes and beneficial insects
• Prevents rain splash on leaves which dramatically reduces leaf molds and diseases
• Looks nice in the garden
• Reduces erosion from heavy rains by dispersing the force of rain drops

So what kind of mulch should you use?  Generally, you want something that is pretty fine and that will break down in the garden within a year.  An exception to this would be mulching perennial herb beds.  A longer lasting (wood chip) mulch on those beds will work just fine. 

A word about wood chip mulch:
A wood mulch in your annual vegetable garden can also work if you are careful to pull it back at planting time.  If the wood gets mixed with the soil then it can reduce the nitrogen available to your plants and it's chunky nature can make it difficult to plant seeds.  Some sources will say that you should never put wood mulch on an annual vegetable garden because it will tie up all the nitrogen in the soil.  What research has shown is that the very top inch or so of the soil will have its nitrogen taken up by the wood as part of its decomposition.  However, deeper in the soil (where most of the plants' roots are) will not be affected.  Wood chips provide a more lasting mulch and as they decompose they provide a much wider and more balanced organic matter to the soil than the other mulch materials often used (grass clippings, hay, straw).  So, the moral of the story is that you shouldn't discount wood chips but you do have to take special care if you use them.

Ok, back to other mulches!  Most of us will end up using an easy and inexpensive mulch like grass clippings or straw.  Old hay can work well, but make sure its partially decomposed or you'll be planting a hay field in your garden.  This can happen with straw too if it wasn't harvested well.  Then you end up weeding wheat out of your garden (been there).  You want whatever it is to be reasonably finely chopped.  Grass clippings will come this way.  You can chop straw or hay by putting it in a bucket or barrel and running a string trimmer in it.  Be careful because this will make a lot of dust and little bits of stuff may come flying out!  Safety glasses are a must!

There are 2 basic categories of things that you will mulch in your garden.  The first includes the big plants - anything that you space a foot apart or more when planting qualifies.  For example: peppers, tomatoes, corn, cabbage, broccoli, cauliflower, tomatillos, cucumbers, squash and potatoes (sweet and regular).  For transplants, you'll mulch as soon as you put them in the ground.  If you're starting from seeds (i.e. corn, cucumbers, squash), you'll want to wait until the plants are several inches tall to avoid smothering them as they start.  Potatoes are an exception - they have enough energy that you can mulch them from the get go and they'll still come right on up.

The second category is the small stuff.  These are almost all started from seeds and usually have a much closer spacing.  Many of these will be planted close enough together that they will create their own mulch once they are a few weeks old.  Beans, peas, carrots and block planted lettuce all fall in this category.  If you're planting them in traditional rows, then you can mulch the sides of the rows and the aisles as soon as the plants are a few inches tall. 

The next question is how much mulch to use?  The answer is LOTS!  A light covering of mulch does almost nothing.  In order to really suppress weeds, it needs to be 6" thick or so.  Even at that, you'll have to top it off halfway through the season to maintain the moisture retaining and weed suppressing benefits.  As you can tell, this means you need a LOT of mulch material!  For some scale, in our garden in town we mulched aisles and beds with a combination of old hay/straw and grass clippings.  We went through 3 round bales of straw/hay each year (roughly 3000 lbs) plus at least a truck load of grass clippings picked up from the neighborhood.  That is for a garden with about 8,000 sq. ft. of annual vegetable growing space including aisles.  I would have used more too if I had it.

Ok, that's the skinny on mulch in your garden.  Happy gardening and keep that soil covered!