Complete information About Azaleas and Rhododendrons.


Hello, I'm Ted Nyquist with the Midwest chapter of the American Rotodendron Society. In the first lesson, we discuss site selection and the factors important for you to consider when planning your rotodendrons. 

In this video, we're going to discuss the factors concerning soil preparation. Soil preparation for rotodendrons and azaleas is just as important, if not more so, than the factors to consider for planning your annuals and perennials. 

The first step in soil preparation after you've identified the site is soil testing and evaluation. I suggest if you don't know a good place to have your soil tested, that you go contact your local extension office for recommendations. 

The goal is to have a porous, well drained soil with a PH somewhere between 4.5 and 6.5. I know there's some discussion in the literature about the exact range and what it should be, and even some literature suggesting that maybe the PH isn't quite as important as some thought it was. 

But there's no doubt in much of the area of the Midwest you're going to have to lower the PH. If the soil doesn't meet your requirements for porosity and PH, you must amend and create a berm. There are areas in our chapters such as Western Michigan, the areas from South Haven all the way up through Traverse City that has very porous, sandy soil which is ideal for planting rhododendrons. 

This porous soil allows for good drainage. Which is critical, and the soil also has a low PH. If you don't have this, you're going to have to create a raised bed, either by creating a berm or using some type of edging such as metal, plastic or wood, in order to create a bed at least eight to ten inches high. 

We use a berm in our garden because we do have the space for it. We have heavy clay soil with a PH of 6.9 to 7.2. I first lay out the area where I want to plant the rotodendrons, and then I kill the grass and other living plants around there with roundup or a similar product. 

After the grass is dead, I then till the soil to the maximum depth that the rototiller will allow. This creates a nice free flowing soil mixture that I can then amend. The goal is to create a berm 18 to 24 inches high. 

Once I've rototilled the soil, I add amendments to the soil in a ratio of approximately 40 30, and I do this by volume or depth on there rather than measuring it out. That's 40% three quarter inch pine finds 30 of a soil amendment and 30 of the soil itself. 

You can also add or use leaves or pine needles. Adjust your soil and give it the porosity you want, as well as non limestone bearing sand or even perlite, which I use from time to time. I use either this grower select pine compost or black. 

Forest soil Conditioner to amend the soil, you may have other things in your area that work just as well. I also add about two pounds of sulfur per 100 soil. Once this is on your bed, then rotatel it in extremely well. 

You can even rotatel it in between the layers that you put on that. And once you have done that, you need to start raising the level of your bed up to about 18 to 2ft tall. I do this by adding that mixture until I get that raised bed of that height. 

Of course, in the spring that will shrink a great deal and the sulfur will have had a chance to decompose and lower the PH of your soil if it's not lowered completely by the spring. You can also add a material such as ionite, which will rapidly lower the PH of your soil and get your beds ready for planting. 

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