QuestionI was recently watching a gardening show that mentioned using cypress mulch, peat moss, high nitrogen fertilizer and something called "expanded shell" when planting azaleas. What is expanded shell and where can I find it?
AnswerHi Connie, "expanded shell" is a term for man-made aggregates. Check with your local concrete manufacturer. They usually have a baked clay product that is used to make lightweight concrete. Do you need it? Probably not!
When planting an azalea, the ideal product to use is a blend of what the plant is currently growing in and your soil. This gives the roots the best transition zone.
Most azaleas are now grown in a pine bark based mix, so use finely ground pine bark at about 1/3 bark to 2/3 of your soil. Make sure the plant is elevated at least 2" above your soil line. Bring the blend up to, but not on top of the rootball so it looks like it's planted on a little hill.
Pine bark has a little calcium in it, so it may raise your pH a tad, but if you are using a well balanced azalea food, it will offset any pH change.
You can add a couple of inches of coarse cypress mulch on top after planting. Pine bark is usually cheap and readily available. You really don't need the peat moss or the aggregate. Jim
