bottom heat and KLN question
 

My Aerangis Fastuosa and Sedirea Japonica like the S/H after about a month, I'm pleased to report. For the first week during the evenings they were placed on a Sunbeam heating pad, and now I'm wondering if that was a good idea since heat destroys KLN. Are the two compatible? The other two in the pictures and Cattleyas and I want to do them soon. thanks, Dan

I don't know, but I use KLN and water with luke warm water and I asked the question here whether the warm water would stop the KLN working.

Ray, who in my opinion is the expert on such things did not think it would.

I don't know if the same is true of the heat pad though. Ray is the person who will know.

Don't worry about it. The rooting hormones are 1) contact activators, meaning that they are absorbed by the plants and "turn on" the activity immediately, and not something that works over an extended period of time, and 2) they are very transient once diluted and exposed to light and even non-heated temperatures.

When getting as plant established, you should probably leave the bottom heat on 24/7 for a few weeks.

What about raising the ambient room temperature (assuming you can keep humidity up). Would that work too, or is there something special about bottom heat?

Tyler

Most professional growers (not just orchid growers) use bottom heat for their plants to encourage root growth and the vegetative growth that follows. Plants respond much better to that than simply raising the ambient temperature. It's the temperature in the root zone that matters most to establish plants. As part of my studies I've worked in greenhouses, and in most places the benches have pipes of hot water beneath them to give bottom heat to the plants. For plants placed directly on the ground, there are also pipes buried in the sand beneath the groundcloth. It's not only good for the plants, but growers save money on heating costs because they don't need to heat the air as much.

Thanks for the information. Very interesting.

Is there any analogy in nature where the roots get a higher temperature than the leaves?

Tyler

Tyler;

The best analogy for soil temps being higher than air temps is the fall growth spurt in cool season turf grasses and root growth in temperate region trees, shrubs, and perennials.

The best time to fertilize these plants is in the fall when air temps are dropping. Lower air temps and shorter daylength reduces top growth and the warmer soil temps promote root growth. Fall fertilization according to the label instructions helps promote strong root growth and builds carbohydrate reserves to help the plant survive winter stresses and get an early start on spring growth.

Cheers.
Jim

I switching to s/h and am wondering about whether it's a good idea to use a heat mat for my paps and cymbidiums, since they generally like cool temps.