QUESTION: I am preparing a planting hole for an azalea. There were some pretty large stones so the hole ended up almost two shovels deep.
They say that double-digging promotes good drainage, but they're talking about preparing a large area. In this case, only the soil in the planting hole has been turned. The surrounding area is compacted and sandy. Will this create a "swimming pool" that will drown the roots?
Don't know if this is relevant, but while digging the hole I broke into a small space with lots of acorns and shredded leaves. If a chipmunk can dig through compacted soil, then maybe water can get through, too?
What are good amendments for sandy soil?
ANSWER: Hi Janet,
Digging and back-filling is good. I would amend the soil with manure, peat moss, compost, etc. In other words, "organic matter". Top-dress with some pinebark mulch - Azaleas like acid soil, which your's won't be, if it's sandy. Use an acid forming fertilizer, like Azalea, Camellia food. In 6 weeks or so, if it's not as green as it should be, you might put a little aluminium sulfate around it to help increase soil acidity.
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QUESTION: Years ago I was advised to stop putting a layer of pebbles in the bottoms of pots for drainage, because having differentiable layers would actually impede the movement of water. No idea if it is true.
For this azalea, does the planting medium need to be homogeneous throughout the hole? Or can I fill the bottom of the hole with less fertile soil mixed with uncomposted leaves?
Less fertile soil will be ok, but I wouldn't put a lot of uncomposted leaves, because as they break down, they are going to create "space" - like an air pocket for water to sit. Plants like to be snugly tucked in!
I disagree with not putting pebbles or broken shard, etc in the bottom of a potto increase drainage. I've rescued too many drowning plants simply by doing just this to increase the drainage.