Campbell Vaughn: Mulch choice matters

There is much to know about mulching!

 

Mulching plant beds is almost mandatory. Bare ground in a shrub bed is not only unsightly, but opens an area to weeds, quick evaporation of moisture, exposure to extreme temperatures and soil erosion.

 

The best way to mulch is up for debate, and sometimes it’s personal preference. I get asked a lot, “Which is better? Pine straw or mulch?” and the answer is, “It depends.” How much do you want to spend? What type of plants is it going around? What are your landscape plans?

Let’s start with the most popular dressing in our area, pine straw. Bales of clean fresh pine straw, when newly applied, can add a fantastic look to your beds. There are three types of commercial pine straw in our area - slash, loblolly, and long leaf. Slash and loblolly are almost identical in appearance with the needles being about 9 inches long. Long leaf has a needle that’s about 14 inches. Slash and loblolly are more common and usually cost about 50 cents to $1 less per bale than longleaf. You should plan to pay somewhere around $3.75 to $5 per bale depending on the type and quality of straw.

The quality of the bale can be assessed by seeing how much non-needle debris (sticks and pinecones) are in the bale, the color of the needles, the length of the needles, and the weight of the bale. Heavier bales equals more straw. Pine straw is usually bought in rectangle bales, which on average cover 60-100 square feet at a depth of about 3 inches. A good thing about pine straw is that if you continue to use straw, you can just keep adding more on top of old. Depending on how the sun and moisture deteriorate the straw, as well as the original quality of the straw, applying 2 times a year should be ample. If you are applying less than 3 inches of straw per application, the need to rake out the old is usually not necessary because of the level of decay. The decayed straw is good for adding organic matter to the soil as well.

Two other good attributes of pine straw are that the needles are loosely intertwined, which keeps the straw from forming a crust (like other mulches) and allows for good water infiltration. Pine straw doesn’t float, so it isn’t likely to be displaced very much when you get heavy rainfall.

Ground hardwood or tree bark mulches are also popular for bedding mulches. They tend to last longer than pine straw but also usually cost more. Logistically, ground mulches can be difficult to use over a large area because you have to move it in prepackaged bags or in wheelbarrows, if bought in bulk. Ground mulch stays in place better than pine bark chunks because pine bark chunks float and the idea is to keep the mulch in the bed. One heavy rainfall could cause your mulch to be spread across your yard.

One problem with using coarsely ground wood and bark is if you need to add some plants (ie annuals) to an area. The mulch has to be raked way back to avoid getting mixed into the planting dirt. Finer ground mulches have a more elegant look and add organic matter back into the soils at a faster rate. It is also easier to add around plants because it moves similar to soft and light soil. Fine mulches are by far the best for use in annual beds.

Consider landscape fabric used as a mat to keep the weeds down. I personally don’t like using it because it always ends up being in the way in the long run. It is almost impossible to remove when it’s time to change flowers in a bed. Proper mulching and proper preemergence, like Amaze or Preen, are better in the long run for your soil.

Some people will use a few layers of newspaper in their vegetable garden to keep the weeds down. I am mixed on this idea because you have to keep the paper moist to keep it from blowing away or find a way to anchor it to the soil. This requires a lot of free time or an irrigation system running once or twice a day, which may cause over watering.

Sometimes rocks are used to top dress a bed. We know they won’t float away or decay; however, they will absorb heat in the hot sun and radiate that heat to the soil and the plant’s roots. This warms the soils to unwanted levels, which can evaporate moisture or keep plants growing in times when they need to be slowing down or do the opposite. Rocks as mulch are best used in areas where they can stay shaded.

Ground leaves and grass clippings are somewhat unsightly, but make for great cover. That would be one of the best possible organic matter additions to your garden. The best perennial bed I ever had was the growing season after I layered the bed with ground leaf mulch.

A couple of last things to consider when deciding how much mulch or straw to buy are how much do you need, how will you get it the needed area and when to apply. Calculate the square footage of the area in need of mulching and the depth you want the mulch to be. Plenty of places will deliver in bulk if there is a large area to be dressed, but don’t expect a couple of bags of pine bark to cover a large area either.

When planning to add mulch, know when is best. Right before a party is usually good, but if the leaves are falling the next few weeks afterward then your beds with be a mix of leaves and mulch until applying again. Planning how much, what kind, when and how you apply will reduce future maintenance, save you time, money, and headaches in the long run.

Reach Campbell Vaughn, the agriculture and natural resources cooperative extension agent for Richmond County, by e-mailing augusta@uga.edu.

 

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