Now that most of us have our summer flowers and vegetables in the ground, let’s talk about mulch. We mention mulch quite a bit, but why is mulch such a good addition to our gardens? Here’s why.

For some people, mulch can seem more like an un-necessary cosmetic addition to a garden, but both vegetable and flower gardens benefit from a good layer of mulch. One of the reasons is because mulch helps protect the soil from our hot, summer temperatures. This provides a couple of benefits.

First of all, mulch can help increase moisture retention in the soil and if your soil is better at retaining moisture, you are not going to have to water as much, or as often. This conservation of resources will help reduce your water bill, raising the cost-to-benefit ratios of your garden. Right now, we have too much water, but it won’t be long until the sun is beating down on us as we are trying to keep track of how many days it’s been since it rained.

In addition, a good protective layer of mulch helps minimize fluctuating soil temperatures. Research shows that non-mulched bare soil can vary in temperature by more than 30 to 40 degrees during the day. These variations in temperature can cause un-mulched soil temperatures to approach 120 degrees during our hot summer days. As you can imagine, there’s not going to be much moisture found in soil that is 120 degrees as most of it will evaporate.

A good layer of mulch can keep this temperature variation down to about 10 to 15 degrees helping keep those roots happier by providing a more consistent soil moisture content rather than our taking a feast or famine approach to watering.

Mulch also keeps soil from splashing up onto plants when you water or when it rains. Now you might ask, why this matters? It matters because there are a variety of fungal diseases that live in the soil. Splashing water helps these diseases migrate from the soil, up onto the plant. This is especially true with tomatoes.

While it’s a very basic, simple solution, mulch prevents this splashing, thereby helping to prevent or reduce the opportunity for disease to find your plants. Also with tomatoes, it’s not a bad idea for your tomato plants to have “bare legs”, meaning that it helps to trim the leaves off the tomato plant up to about a foot above the ground to again, help minimize the potential for disease transfer.

One of the main things people think of as a benefit of mulch is that of weed reduction in your garden. Once again, mulch comes to the rescue by providing a barrier between the pesky weed seeds and the sun, helping to minimize germination and the growth of weeds. As far as I am concerned, weeding is one of my least favorite things to do in the garden and anything to reduce the time I spend weeding is a good investment in my book.

Knowing all the benefits that mulch brings to our gardens, the question then becomes “what kind of mulch should you use?” For the most part, we recommend organic mulches. I say for the most part since at our Seed to Supper Farm, we use thin, plastic sheeting as a mulch to both minimize weeds and improve moisture retention for our crops. But not everyone is caring for a 3-acre farm. At home, there are a variety of mulches that work quite well.

As a rule, organic mulches are better than non-organic mulches. A non-organic mulch would be something like ground up automobile tires. In this instance, we suggest you just say “no” to non-organic mulches. Yes, these non-organic mulches will probably last longer than organic mulches, but they also come with fewer benefits.

We prefer organic mulches because these mulches decompose over the growing season, putting organic matter back into the soil and in our locale, organic matter in the soil is lacking. Typically, our soils have about 1% organic matter, when we want something closer to 6% so anything you can do to add organic matter to your soil is a plus.

If you read this weekly column, you know I suggest mulching those fall leaves, saving in bags till spring, and then using them for garden mulch. I did this every year, but we moved recently, so I am going to have to be a little more creative in sourcing inexpensive mulch.

A great option available to residents of Tulsa County is Tulsa’s Green Waste Site located at 2100 N. 145^thE. Ave. The good news is that there isn’t a residency requirement to pick up mulch. If you have a pick-up or trailer, they will load it up for you with a tractor. The rest of us will have to bring some sort of containers to pick up our mulch. Either way, we have access to all the mulch we need at this site.

Specialty mulches are available at most garden centers and in a variety of colors. I am not a big fan of colored mulch, but most definitely I would suggest you stay away from the black mulch. If you think about it, we want our mulch to provide a heat barrier for our soil and since black is a color that absorbs heat, this heat protection is diminished with black mulch.

There are a variety of other mulch materials available, and we have a good fact sheet giving the pros and cons to each of these. You can find it on our website (www.tulsamastergardeners.org) in the Lawn and Garden Help Section/Vegetables. See you in the garden!

You can get answers to all your gardening questions by calling the Tulsa Master Gardeners Help Line at 918-746-3701 or by emailing us at mg@tulsamastergardeners.org. Photo: Master Gardener Steven Hall