How to Build a Propagation Soil Warmer

My father straightened nails and re-used them. Some nails on our chicken farm had first been bought during the Hoover administration and had been used over and over since. Innumerable gallon cans full of nails, bolts, screws and washers were scattered in our sheds and barn. When the wood siding fell off the chicken house or when fertilizer spreader lost a washer, he could count on having a slightly used fastener close at hand.

Many of us grew up with Depression era parents and became used to their obsessive saving of jar lids, plastic bags and rubber bands. My father saw straightening a bent nail as a cent earned and a trip to Travis Hardware in Fayetteville avoided .

Genetics must run strong in my body because it always tickles me to make something useful out of scrap. I recently decided to learn more about propagating houseplants. One of the first things I discovered is that the process of rooting leaf cuttings is made easier if you keep the soil warm while the plant leaves sprout roots. Most references recommend an electrified rubber soil propagation mat (click for sources), which costs money.

ONE PERSON’S JUNK IS…. Much to my family’s discomfort I keep an above-average amount of junk (their words) in our basement. But to my delight, among the junk, I saw the ingredients for a simple warming pad that would cost me only a few dollars.

I reasoned that low wattage light bulbs could warm a metal tray from beneath and I could put my propagation tray on top, thus keeping the soil warm as the roots grew.

I first made a frame from four pieces of scrap 1×4 inch wood. The dimensions were determined by the height and width of a flattened aluminum cookie sheet, my only expense.

Inside the wooden frame I attached two random porcelain sockets, wiring them with a cord I’d salvaged from a fan that bit the dust years ago. Two fifteen watt bulbs were screwed into the sockets.

After spray painting the cookie sheet black, I attached it to the top edge of the frame with screws. Although my family reacted with chagrin, I’m sure my father would have been proud.

ROOTING LEAF CUTTINGS Many common house plants can be rooted by inserting sections of their leaves into damp potting soil. Jade plant, snake plant, kalanchoe, Christmas cactus and begonia are easy ones with which to start. Half-fill a shallow plastic tub with moistened, sterile potting soil. Snap individual leaves from jade and kalanchoe plants and insert them half-way into the soil. Use scissors to cut two-inch sections of snake plant and insert into the soil likewise.

Cover the tub with clear kitchen wrap and place it on the previously constructed heating pad. After an hour, check the temperature of the soil with your fingers. It should be barely warm. If it seems hot, put a couple of pencils under the plastic tub to raise it a bit and lower the soil temperature. Put the entire contraption in a sunny window and wait a few weeks. Roots should form readily. When small plants sprout at the base of the leaves they can be transplanted into individual pots to be given away to friends and neighbors. The setup can be used again and again and you’ll save lots more money than by straightening nails all your life!