Grow Cool Plants

If you’re like me, pretty much every orchid is fascinating, and – if I had the room – I would want to grow them all. Even ignoring that “minor” detail about growing space, we have to face the fact that some plants are just not right for the conditions we can easily provide. In my case, “cool plants” have always been a challenge, and that is more the case since I moved to North Carolina.

In our article about the applicability of semi-hydroponics, we wrote about taking advantage of the evaporative cooling effect of moist LECA to create cooler environments on a localized basis. While changing a plant to S/H culture works well for many, if you don’t want to make that change, you can still use the concept with your existing potted plants. We can think of this as a “semi-hydro-hybrid” approach.

All you need is an unglazed clay pot that is about two inches taller and about three times the diameter of the one holding your plant, a waterproof tray to set the larger pot in, and a small amount of Lightweight Expanded Clay Aggregate (LECA).

Place a layer of LECA in the bottom of the clay pot, adjusting the depth so your plant’s pot sticks up a bit above the rim of the larger pot. Center the plant in the pot, fill in all around it with LECA, place it in the tray and fill the tray with water.

The water will wick upward, wetting the LECA without changing the moisture content of your original pot, but with the evaporation from the pellets and through the clay pot wall, the temperature should be significantly reduced. If your tray has enough capacity (or you empty it beforehand), you can just water your plant normally, and the drainage will refill your tray.

A couple of caveats: If your ambient humidity is high, don’t count on there being all that much cooling, and do expect your plants to send their roots down into the LECA!

Using Science & Logic to Improve Orchid Growing