We’ve all read or heard gardening stories boosting the magical powers of Epsom salt, or that your wood ashes will provide needed nutrients to your garden. Truth be told, many gardening tips and products are beneficial in specific regions and harmful in others. Sorting through the information and row after row of soil products at the local garden center can be a bit overwhelming. I’ll touch on five of the items I’m asked about most, hopefully simplifying your next shopping trip & improving your garden.
Products that lower Soil pH
Bottom Line: Not practical
The pH range for most soils in Iron County is 7.0-8.0, which is fine for most garden crops, but not ideal for growing acid loving plants, like blueberries. The thought of growing something uncommon prompts many gardeners to attempt to lower their soil pH with products like peat moss, vinegar, elemental sulfur, acidic fertilizers, etc. While it may be possible, it’s important to keep in mind that the pH of our irrigation water is similar to that of the soil. If you are successful at lowering the soil pH but do nothing to treat the water, eventually things will shift back to their original state. Long story short, lowering the pH of your soil can be a lengthy and expensive process. I always suggest that homeowners embrace their existing environment and choose plants that are suited for their areas. If you just can’t help yourself, think small. Try growing your blueberries in a container, which will allow you to have a bit more control.
Bottom Line: Extremely beneficial when used properly
Compost can be plant based, animal based, or a combination of the two. Manure-based composts are easy to find, but are often high in salts. This isn’t a bad thing, high salt content translates into high nutrient content, but you’ll need to limit your application rates. Plant-based composts are low in salts, which allow them to be applied at a higher application rate, making them a great choice for improving poor soils.
Bottom Line: Not the best idea
Wood ashes and limestone both raise the pH of your soil. Iron County soils are naturally alkaline, or higher on the pH scale. Raising the pH even further will create problems in the garden & landscape. It’s best to throw your ashes in the garbage, after they have cooled of course.
Bottom Line: Not usually necessary
I get a lot of phone calls from people inquiring about the use of Epsom salts in their garden. Put simply, Epsom salt is magnesium sulfate. If your soil is deficient in magnesium, the product can be beneficial, but most UT soils are not.
Sphagnum Peat Moss
Bottom Line: Great product, but not environmentally friendly
Peat moss has a lot to offer. It improves nutrient retention, breaks up heavy soils, and can temporarily lower your soil pH. The downside, sphagnum peat moss is mined from peat bogs that take centuries to form. In addition, these bogs are the single largest terrestrial store of carbon. While peat is great in the garden, so is compost, which provides most of the same benefits & is a more sustainable option.
We always recommend adding a 2-4” layer of mulch around landscape plants. Whether it’s something organic that adds nutrients to your soil like shredded leaves, putting, grass clippings, or shredded bark (my personal favorite), or something different like rubber mulch, or rock, they all have benefits and will help retain soil moisture.
Bottom Line: Depends on the intended use
Sand is a great addition to a raised bed garden mix. We usually recommend 40%-50% compost mixed with 50%-60% sand combination for raised bed gardeners. Sandy soil is easy to work with and warms up early in the spring, which promotes faster seed germination. Sand is NOT a soil amendment that should be mixed with clay soil. Mixing the two will result in a concrete like soil texture. Incorporating compost into clay soils is your best bet for improving soil texture and structure.
Stop by the USU Extension Master Gardener booth at the Spring Home & Garden Show to see & touch some of these amendments.
Iron County Horticulturist