Bottoms is Tops

Every gardener and grower will tell you that propagation is all about increasing the percentage of attempts that actually produce viable plants. The odds in your favor increase with the use of bottom heat and bottom watering, and here’s why.

Some plants do not respond well to overhead watering, such as roses and African violets. Their leaves are vulnerable to fungus diseases that need water to get going and without it, fewer disease problems arise. We’ve all heard that watering roses and lawn grass before dark works to prevent those fungus diseases, too. Given that rain does fall at night, it is wise not to compound that problem. The same goes for cuttings and seedlings, but another factor comes into play for them. They are small, easily disturbed, and also may be slowed by the introduction of cold water to the environment. I run tap water into a container and let it sit until it is no longer chilly, and then fill the flat or saucer underneath cuttings. No cold shock, no wet leaves or toppled stems, and better rooting percentages.

The need for bottom heat in the form of a heating mat made for use in propagation setups can be even more important for rooting and seeding. The reason we set up a rooting chamber of any sort is to create conditions where the cutting will develop roots before it rots or dries out. A warm soil provided by the heating mat keeps the process going and speeds rooting as well. Your modest investment in a heating mat will pay for itself many times over, but not everyone agrees. One of my own gurus insists that bottom heat rarely makes the difference for most plants, and if needed, it is readily available in most homes. Yes, it’s true that the top of old-fashioned refrigerators and water heaters can be warm enough, but new, energy-efficient models don’t leak heat like the old ones. Maybe he’s better than I, but my success rate with bottom heat is far superior to other efforts. Get a mat – you’ll be glad.

I do not want first time propagators to be daunted by the elements needed to set up a rooting chamber. As I wrote about in last week’s blog, it can be quite simple. Truth is, sometimes you don’t need much of a setup at all. Rooting figs and other woody plants often happens because we prune the plants and cannot resist trying to start another one. My grandmother had a reputation for being able to grow broomsticks and proved it. I played in the yard while she cut back the French hydrangeas on a warm day in February. Her way of doing it was, like most things, pretty original. To keep the bushes under the windows, she cut back some of the stems fairly hard each year, while on the others, she just trimmed the tips. As she went down the hedge, she discarded the tips but rooted the long, woody stems. Almost absentmindedly, she trimmed each one to a foot long and stuck it into the soil next to its parent. The result was always plenty of flowers and thick, leafy stems. She dug up a few as gifts once they took root, but most grew right there and kept the planting full and fresh for 30 years that I know of. Since then, I’ve rooted figs, grapes, and even crepe myrtles using this method with stems about as big around as a pencil and some larger than that. But I add one important step that increases my success rate considerably. I put a little Hormex rooting hormone powder into an envelope and carry it with me when I prune. I dip each new cutting into Hormex, and recommend that you do, too.


Nellie Neal is a passionate propagator and owner of GardenMama, Inc. She advocates for gardening 24/7 at her website, Ask questions and comment about this blog on the Contact Us page of

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