My Soil, My Encores – I amend with gravel and let the water flow

By Mary-Kate Mackey

Encore® Azaleas need soil that drains well.

Encore®Azaleas need soil that drains well. Like many garden plants, if they’re grown in dense soil, not enough air can get to the roots. Last fall, I boldly put in 16 Encores – two in containers, the rest in the ground. And yet, my Oregon garden has heavy clay.

I joke that it’s “20-minute” clay. There’s 20 minutes to work with it from the time it’s too wet, until the moment it becomes brick hard. It collects on your boots, building up until you’re carrying pounds on each foot, and you have to stop and kick it off.

Over the years I’ve amended like mad. I did sheet composting, piling up massive amounts of decaying matter, building the height to my knees and then letting it rot down before mixing it in. That helped. I never made a planting hole that I didn’t amend with my local favorite – mint straw. It’s a by-product of Oregon mint production after the plants are steamed in the fields and the oil is distilled. I’ve mulched every bed repeatedly. I’ve added stepping stones among the plants so I’m not compacting the soil when I weed.

Everything helps. The top 8-inches has become darker and the texture has improved. Earthworms are now found. But if I don’t keep up this intensive care, the amendments disappear, and the clay rules.

Yet, with all this, I went ahead and planted my Encores. Why?

Because a few years ago, I heard Maurice Horn, of Joy Creek Nursery, talk about another amendment – sharp quarter-10 gravel without fines. Different parts of the country sell it by other names. It’s approximately a quarter-inch in size. Without finesmeans it’s washed clean – any small particles would turn the clay into concrete. It must be jagged-edged, not rounded pea gravel. Maurice uses it at his own nursery on a hillside that receives no water in the summer, and in a small lawn that was getting ruined by visitors’ foot traffic. 

I figured I didn’t have much to lose. In 2012, I seeded a new lawn in a soggy area of the garden, mixing the quarter-10 into the top 8-inches. Once the grass was established, water use went way down.

Encouraged, I tested it in a garden bed. I added it at the rate of a 2-heaping-inches of gravel, plus 2-inches of mint straw, dug 8-inches in. The results were so spectacular I ordered a ton of the gravel. It goes into every planting hole I make. 

So, when I placed the Encore® Azaleas in the ground last fall, gravel was an important addition. The sharp stones permanently help keep the clay more open. Clay has plenty of nutrients if air can get in there. The gravel mitigates the soil temperatures. The rocks are slower to heat up in summer and cool down in the winter. 

You grow, Encores!