Houseplants Laidback Gardener Tip of the Day

When Water Droplets Form on Leaves

What is Guttation?

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Guttation mostly occurs on leaf tips or edges.

Sometimes you’ll see water droplets form on the edge, tip, or the underside of leaves. This is not dew, which tends to occur mostly outdoors when the air is humid and the night cools off considerably. Dew comes from water condensing from the air and tends to form fairly evenly on the leaf’s upper surface. The drops discussed here come from inside the leaf and are more evident when the air is relatively dry. The formation of such droplets is called guttation.

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Dew forms on the upper surface of the leaf.

Guttation occurs when the soil is too wet. Too much water penetrates the plant through its roots and this can create pressure that forces the moisture to exude from the plant in the form of droplets. Guttation doesn’t occur during the day, because the leaf’s stomata are open at that time and are able discharge any excess moisture in the form of vapor. It’s when the stomata close down at night and water pressure begins to build up that guttation occurs. You’ll therefore most likely notice it when the sun comes up in the morning, before the drops evaporate.

Outdoors and In

Not all plant guttate. Grasses, though, are well-known for this phenomenon, which is mostly readily seen outdoors. Among houseplants, water droplets on the leaf tips or edges are most commonly seen in aroids (dieffenbachias, philodendron, monsteras, alocasias, etc.) and bananas, while plants in the grape family (Vitaceae, like cissus (Cissus spp.), chestnut vine (Tetrastigma voinerianum) and leea (Leea guinensis) tend to form droplets from the veins on the underside of their leaves. You may also see a drop appear on the underside of the leaf of some figs (Ficus spp.), where it joins the petiole.

Harmless

Guttation causes absolutely no damage to the plant. At worst, as the drop dries, it may leave behind a smidgen of white deposit (coming from minerals and sugars exuded along with the water) or dried sap. In nature, bees often seek out these drops for the sugar they contain.

Although guttation is harmless, it may however indicate a problem with the way you care for your plants. If you regularly see guttation, it’s possibly because you water too generously. Always apply the Golden Rule of Watering – let the soil dry out before watering again, then water thoroughly – and then guttation will cease. Also, if you water in the morning, there will be less risk of guttation that if you water in the evening, as any excess moisture in the soil will have had time to be absorbed or to evaporate before the stomata shut down for the night.

 

 

Larry Hodgson is one of Canada’s best-known garden communicators. He has notably been editor-in-chief of HousePlant Magazine, Fleurs, Plantes et Jardins, À Fleur de Pot and Houseplant Forum magazines and is currently the garden correspondent for Le Soleil and radio garden commentator for CKIA-FM Radio. He has written for many garden publications in both the United States and Canada, including Canadian Gardening, Harrowsmith, Horticulture, Fine Gardening and Organic Gardening. He also speaks frequently to horticultural groups throughout Canada and the U.S. His book credits include The Garden Lover’s Guide to Canada, Complete Guide to Houseplants, Making the Most of Shade, Perennials for Every Purpose, Annuals for Every Purpose, and Houseplants for Dummies, as well as nearly 60 other titles in English and French. He is a past president of the Garden Writers Association (now Garden Communicators International) and the winner of the prestigious 2006 Garden Media Promoter Award offered by the Perennial Plant Association. He resides in Quebec City, Quebec, Canada.

7 comments on “When Water Droplets Form on Leaves

  1. Very well explained. Henceforth, I shall be more careful about watering house plants.

  2. Pingback: Where Does Pepper Come From? – Laidback Gardener

  3. Polly Sullivan

    This was the best expiation that I’ve read. Helpful and understandable. Thank you.
    I have a different question. I have had for three or four years two Amaryllis which have flowered consistently. This year they have out done themselves. One flowered three times and has produced three offshoots. The bulbs are half the size of the parent. But the parents have tiny red spots or blotches throughout the leaves. All I’ve read is it’s a disease and to throw them out. Is there alternative solution please. They look healthy in all other respects. And can I do anything to prevent these new bulbs leaves from being contaminated? A long comment. My apologies. Polly

    • First, do make sure it really is red blotch disease (a fungus). Light physical damage to amaryllis leaves can result in red marks and that is, of course, not a disease and new growth will come up healthy. I suspect that, since your plants appear otherwise healthy, it’s probably just that.

      If new growth always comes up with red markings and is weak and unhealthy, it probably is the fungus and the only logical solution is to dispose of the infected bulbs. You could try the following heat treatment, but it’s not easy to give:

      Dig up the bulbs, remove infected scales and excess soil, and soak them for 30 minutes in water kept at a temperature between 104°F–114°F (40°C–46°C).

      • Polly Sullivan

        Thank you for replying so quickly. I really didn’t expect that. I will go with your first suggestion as the offshoots do look really healthy. Despite having the little red dots on the leaves. Light physical damage? Move out of the window, even though the one plant has given so much back? Many thanks. Polly

      • As long as the leaves are green (ignoring the red spots), continue to give them as much light as possible.

      • Polly Sullivan

        Thanks.

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