Get two serious gardeners together and chances are they will disagree on many issues. There are a couple of reasons for this. First, most seasoned gardeners learn by doing rather than just reading. That is not to say that they don’t read gardening books and magazines. They do. Many are voracious readers. But rarely do they take the information gleaned from books and rush out and incorporate it into their gardens. Unless there is a burning environmental issue, their first rule of thumb is, if it ain’t broke don’t fix it. Avid gardeners realize that every garden is different – what works in one may not work or may need adapting to work in another.
So it wasn’t surprising that Martha Stewart’s syndicated column on soil preparation that ran in Homestyle last April stirred up controversy among avid gardeners and professionals in the green industry. While much of the information was sound advice, start with soil test, amend with organic materials and incorporate raised beds, some recommendations were considered misleading and others way just way too much work.
Christa Suggs of Christa’s Ponds and Gardens in Washington and I both have serious issues with Martha’s suggestion to use raised beds to conquer boggy soil.
It has been my experience, when you step in a true bog, you better wear boots because you may sink up to your ankles in black muck. A bog may be a low lying area that collects water, but some bogs are fed by underground springs. They rarely dry out.
So, Stewart’s suggestion to rototill organic amendments, such as builder’s sand and composted pine bark into existing boggy soil in such a quantity as to raise the soil level 6 to 12 inches, didn’t sound like a very good idea to either of us. You can’t rototill a swamp.
Also, if the area is considered a wetland by the state of Michigan, it may be protected by law from any alteration.
Suggs and I both agree, if your patch borders on a boggy land, your best bet is to take up bog gardening and choose plants that thrive in that type of environment rather than fight Mother Nature. And, from a practical standpoint, America’s Master Handyman, and fellow Homestyle columnist Glenn Haege counsels, “water always wins.” So if you want to grow petunias around a boggy site, plant them in containers.
Of serious concern to me was Stewart’s recommendation to include cottonseed meal as an amendment for improving soil with a neutral pH. While it wasn’t stated in the article, I assume it was included to acidify the soil to an optimium pH of 6.2. There are a couple of important issues here worth considering. First, most garden plants will thrive in soil with a neutral pH of 7, so unless you are growing true acid loving plants, there is no need to attempt to lower it. Also, research has shown that adding organic matter to the soil will help to buffer the effects of both high and low pH soil. For more than 30 years I have been successful growing in alkaline soil with a pH of 8, by amending it with shredded leaves , compost, and composted manure.
More important, cottonseed meal is an organic fertilizer used as a source of nitrogen. While it is acidic, cottonseed meal nor any other fertilizer, should never be used to attempt lower the pH of soil. The addition of excessive amounts of nitrogen to the soil will kill beneficial soil dwellers, burn plants, promote lush weak growth, and pollute the ground water. Not a good thing.
On a small scale, amending with Canadian sphagnum peat moss will temporarily lower garden soil’s pH. On a large scale, amendments such as finely granulated garden sulfur will do the job without adding excessive nutrients that can be damaging to both plants and the environment. However, attempting to raise or lower the pH of a large area is an expensive and long-term proposition. And the soil should be tested on a regular basis order to determine recommended amounts.
Martha also suggested using gypsum along with compost to help break up heavy clay. On certain types of clay found in other regions of the country, gypsum is effective as a clay buster. But research by Michigan State University suggests that gypsum does not work on Michigan clay. Fine ground composted pine bark sold as a soil conditioner does a good job. I’ve made my own by putting pine bark mulch through a shredder and composting it over the winter.
To improve gravel soil Stewart suggests sifting out stones larger than half an inch and rototilling in a 6 to 12-inch layer of compost and soil. In a society where most folks don’t have the time to sift enough flour to make a cake, suggesting that we gardeners sift the top six inches of soil in a garden is ludicrous. And, as for rototilling gravel beds – not with my Mantis tiller. My solution would be to dump the topsoil and compost on top of the gravel and plant away or do some research and become a gravel gardener.