Author Ellen Vande Visse

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The Scoop on Coir

(Coconut Husk Growing Medium)

Coir is coconut husk fiber. Two other names for this same material are Coco peat and Coconut coir. Coconut husks are washed and dried multiple times, then compressed into dry bricks. Coir is a renewable resource, and once considered a waste product. Compare this to the damaging effects of harvesting peat moss for peat-based potting media on the market. Peat bogs take centuries to regrow once strip-mined.

Reasons to buy coir instead of….

  • More sustainable resource than peat
  • Coir is pH 7 compared to peat moss, which is acidic
  • Coir provides excellent moisture retention, soil drainage, and aeration
  • Costs about 1/3 the cost of ProMix for same volume


Quality: All Coir Is Not the Same

As a buyer of coir, you cannot easily tell what brands are high or low quality, because coconut trees mostly grow in saline, brackish soils along sea coasts. This results in
the husks being very salty. Typically, lower quality coir is washed 3 times to remove excess salt, but this process renders the husks nutrient-deficient. Cec Ellsworth is the developer of Boreal Coir, a brand which he distributes from Wasilla. He sources coconut
husk grown in India, 200 miles inland. He makes Boreal Coir from the finer material that is left over after the long fibers have been removed from the coconut husk. This is
also washed and dried 3 times. Then it is soaked in a calcium nitrate solution to buffer it and helps it maintain a stable pH.

Recipe for Potting Medium
Cec mixes 10% worm compost into his raw Boreal Coir, and then adds some of his own mycorrhizal fungi. He does not add perlite or vermiculite, since coir does not readily compact. This blended medium works well for pressing into soil blocks, as well as filling pots and building garden beds.

Fertilizing Seedlings

Initially Boreal Coir provides seedling nutrition from the worm compost in it. As seedlings develop, apply compost tea every 8-14 days.

Where to Buy Boreal brand Coir (Note:  not available spring 2022)


Blocks (not bricks) weigh 11 pounds. Dimensions 12” x 12” x 5+” Blocks require soaking in 9-10 gallons water in a very large tub or wheelbarrow. 1 block (not a small brick) swells into 3 cubic feet once soaked.

Prices for his brand, Boreal Coir
He sells by the pallet-load or individual blocks.

  • 1 block ……. .$12/each
  • 10+ blocks…..$11/each
  • Pallet ……… $9.50/each block