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Sunday, February 28, 2016

Sustainable-enough potting mix

To test the usefulness of my homemade potting mix and compare it to commercial products, I’ve been working this winter on propagating African violets. I made the potting mix to avoid using peat, which I learned is not a renewable resource. The mix is half compost from my yard and half coir, or coconut fiber.

    Like so many of my gardening methods, it’s “sustainable-enough” rather than ideal. That’s because the coir comes from Hawaii, accruing significant carbon cost on its 6,000-mile journey to Massachusetts. On the plus side, coir is a byproduct that I can put to good use, and compared to depleting peat bogs, which are major carbon sinks, I think non-local coir is the better alternative.

    I’ve had luck with African violets as houseplants probably because they tolerate neglect. My collection has been living for years on pebble trays next to an east-facing window. Their winter blooms are a morale booster. I’ll betray my amateurism by admitting that I haven’t kept track of the names of the varieties I’m growing. My favorite has blue flowers and purplish foliage. 

The pink ones are nice too.

    I wanted to try multiplying my collection by rooting single leaves. I cut off a few with stems about two inches long and stuck them into moistened potting mix in November. I enclosed them in plastic bags for a humid environment and put them under a grow light in the kitchen. Nothing happened for many months.

    Meanwhile, I discovered an excellent youtube video demonstrating how to propagate African violets from leaves, made by an anonymous benefactor who obviously knows what she’s doing. After watching her demonstration, I was able to start a new batch with several improvements in my technique.

    First, since the new sprouts grow from the cut end of the stem, I cut the stems shorter. I used smaller pots and didn’t tamp down the potting mix. I learned to cut the stems at a slant for more surface area and to cut the leaves in half to encourage them to put their energy into reproduction rather than photosynthesis and leaf enlargement. 

    This week I noticed some little leaves growing up at the base of the old ones in both batches. 

I took the pots out of their plastic bags and gingerly dug out the mother leaves. Voila! There were little plantlets growing from the cut ends. The new leaves were no more than a quarter inch long, some much smaller, but they had their own roots. 


    I pulled the babies away from the mother plant, doing my best not to break them. I planted the best ones in a recycled six-pack from last year’s garden center annuals, 

encased them in another plastic bag, and replaced them under the grow light. With luck, I’ll have reasonable-sized plants to enjoy or share next winter.

    The non-peat potting mix did its job just as well as the peat-based mix I used to use. Score one for sustainability.

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