Heath family plants have special soil requirements

The Associated Press
Friday November 24, 2000

Plants of the heath family – azalea, rhododendron, mountain laurel, blueberry, heather and heath – grow wild in the soils having the unique combination of being very acidic, rich in humus yet infertile and moist and well-aerated.  

You can grow these plants if you pay attention to their rather exacting soil requirements. 

First, test soil acidity either with a home test kit or by taking a sample to your Cooperative Extension office.  

Heath plants require a soil pH between 4.5 and 5.5.  

In very alkaline soils, where it may not be feasible to lower the pH and keep it there, replace the soil from a hole 18 inches deep and 2 feet or more in diameter with a mix of equal parts sand and acidic peat moss.  

Otherwise, just acidify existing soil with powdered sulfur, per soil test recommendations, spreading the material as far as the eventual spread of the roots. 

Supply humus by mixing a bucktful of acid peat moss or composted sawdust right into the planting hole. Peat moss and sawdust decompose slowly in the soil so their benefits are long-lived. 

With the soil prepared, open up a hole wide and deep enough to accommodate the plant’s root ball.  

Slide the plant out of its container and set it in the planting hole on a mound of soil so it is at the same level as it was in the pot.  

Backfill the soil, then give the ground a thorough soaking. 

An organic mulch, such as leaves, pine needles, straw, wood chips or sawdust, will provide the cool, moist conditions enjoyed by plants in the heath family.  

And as these mulches decompose, they will further enrich the soil with humus. 

Avoid manure as a mulch, though. It is too concentrated in nutrients for the delicate roots of these plants. 

Lay 3 to 6 inches of mulch on top of the ground. As with the sulfur, spread the mulch as wide as the eventual spread of the plant. 

Mulch is especially important following autumn planting. Mulch lessens alternate freezing and thawing of the soil so a young plant, as yet poorly anchored in the soil, is less likely to be heaved up and out of the ground during the winter.  

Mulch also delays freezing of the soil in autumn, so the plant can grow as many roots as possible before the first breath of spring brings on growth of new shoots.