Getting coco coir ready before you plant

Coco coir is ground coconut husk. It can hold air and water well, but it isn’t sterile, and a few quirks catch beginners out.

What to buy

• Choose coco labeled washed and buffered, and ideally pasteurized. Researchers found unpasteurized coco fiber can carry mold contamination.
• Mix it with perlite so it drains quickly. About 70 percent coco to 30 percent perlite is a common mix.

If you buy a raw brick

1. Follow the manufacturer’s hydration and rinsing instructions. If washing is needed, check EC against your source water. Water that looks clear doesn’t prove the salt level is low.
2. For unbuffered coco, use the supplier’s buffering procedure and a product made for that purpose. Concentration and soaking time depend on the product. Don’t guess at a “mild” dose, and don’t automatically re-buffer coco that’s already prepared. Buffering deals with ion exchange; it doesn’t sterilize.

Feeding coco

Coco doesn’t supply a balanced fertilizer program, though it can contain potassium, sodium and other ions. In unamended coco, use a complete nutrient program suited to young plants, and account for any starter fertilizer already in the mix. Watch young plants for signs of calcium or magnesium shortage, and see the Cal-Mag guide.