Garden Myths - Learn the truth about gardening

Water When Plant Leaves Wilt

When the leaves of a plant wilt it is a sign that the plant needs water, and therefore it is a good time to water–right? Maybe. The plant might need to be watered, but it is also possible that water will harm the plant.

Water When Plant Leaves Wilt

Water When Plant Leaves Wilt

Why do Leaves Wilt?

When we get thirsty, our bodies are letting us know that we need more water. It is a feeling we have. Other people looking at us can’t really tell we need more water. Part of the reason for this is that we have a skeleton structure that keeps us standing straight. Green leafy plants don’t have a similar structure; they use water pressure to keep them standing upright.

You can think of the plant leaf as being similar to a garden hose. With the water turned off, the hose is limp–its wilted. When we turn the water on, the water pressure inside the hose increases and the hose becomes stiff. The stiff hose no longer looks wilted. Plants work exactly the same way. In order for a plant to maintain its normal shape it needs a certain amount of water pressure inside the leaves.

Water pressure is maintained in the leaves by the roots which are absorbing water from the soil  and pumping it up into the leaves. Leaves naturally loose water, especially during photosynthesis. Water is constantly flowing from the roots to the leaves.

If roots can’t get enough water, they can’t maintain the correct water pressure in the plant and the leaves droop or wilt.

Why Can’t Roots get Enough Water?

When the soil gets dry, the roots will be unable to get enough water. If this is the problem, watering the soil will certainly help and wilted plants will regain their turgor (ie stiffness).

There is another possible reason why plants can’t get enough water. The roots may be damaged. If the normal root size is reduced substantially, you have a situation where there are not enough roots to get enough water for the whole plant. In this case the soil might be quite wet but the plant will still wilt. Adding  more water will not help.

Roots might be damaged during transplanting or they might have rotted.

Damaged Roots During Transplanting

When you move a plant, especially a larger established plant, you will damage a lot of roots. It is quite normal for such a plant to show wilting right after being moved.

It is quite common for people to water far too much after transplanting in order to try and fix the problem. Too much water does not help the problem. One solution is to move plants in spring and fall when the temperatures are lower and plants are not growing at full tilt. At these times of the year water evaporation from leaves is less and you get less wilting.

If you do move a plant in summer, it will wilt much less if it is covered for a week or two so that it receives less sun light.

Rotting Roots

Over-watering a plant can cause the roots to rot. Some diseases can also cause roots to rot. With less roots, the plant wilts. Some people will then water the plant even more, causing even more root rot.

Wilted plants should only be watered if the soil is dry. If the soil is not dry, it is not a water problem and watering can only make things worse.

Does Wilting Hurt a Plant?

The short answer is YES. Occasional short term wilting will not do too much harm, but it is still not good for the plant.

Some people think that wilting is a natural phenomena in plants and it shows that they are conserving water. That is simply not true. When plants do not have enough water they go into crisis mode. They stop growing, they close stomata to conserve water and they shut down other vital processes. Wilting is a sign that the plant is in crisis mode. If this is due to a lack of water, the plant should be watered right away to reduce long term damage to the plant.

Some plants, like ligularia, which have very large thin leaves, wilt more easily than most plants. By mid-day my ligularia are all wilting even when grown in shade and in wet soil. By 6:00 pm they are back to normal, showing fully stretched out leaves. Is this the best situation for these plants? NO. But some plants are better able to survive the crisis than others and a few hours of wilting does not seem to cause permanent damage to ligularia.

The best time to water is the day before the plant wilts. Wilting is never good for a plant.

References:

1) Photo Source: Mountain Empire Community College

Robert Pavlis
Editor of GardenMyths.com
I live in southern Ontario, Canada, zone 5 and have been gardening a long time. Besides writing and speaking about gardening, I own and operate a 6 acre private garden called Aspen Grove Gardens which now has over 3,000 perennials, grasses, shrubs and trees. Yes--I am a plantaholic!

I hope you find Garden Myths an educational site that helps you understand your garden better.

19 Responses to 'Water When Plant Leaves Wilt'

  1. how about a post on the myth that watering with cold water is bad for plants?

    • Is it a myth? Cold water can damage plant leaves and roots. The important thing is the degree of cold. Most water from hoses is not very cold and so does no harm. I have added it to my list of future myths. Thanks.

  2. Darlene says:

    I moved some of a ligularia plant but I don’t know if I took enough roots. The plant is really wilted. Do you think it will die?

    • Probably not – they are tough plants. Try to water well and keep the plant covered as much as possible. Shade keeps it cooler and reduces water loss from the leaves.

  3. David says:

    I have a momosa silk plant “12 it arrive with wilted leaves and lowered stems. The roots just had moisten towel paper wrapped in a plastic bag. I put it in wet soil and still a day later looks exactly the same. Is it dead. I need to know so i can get my money back or replacement

  4. Thank you for this article. I found it when trying to figure out how much harm occasional wilting might be doing to my potted tomato plants.

    I recently moved to Austin, TX, and so at first I was watering my container tomatoes moderately but frequently… until I got blossom end rot. I’ve treated the plants for that and changed to watering them deeply but only twice a week, which is working for the BER. Unfortunately, due to the hot & sunny climate this means that in trying to wait longer between waterings, the plants sometimes wilt.

    So, now I’m trying to figure out how to balance the two potential problems: damage from wilting (once every week or two so far, but maybe more as the summer gets hotter), or damage from the blossom end rot? I want some tomatoes to actually successfully ripen, so for now I’m going with the wilting!

  5. Kyle says:

    I grew chilli pepper seedlings indoors and transplanted them into larger containers and placed them in our outside greenhouse I watered them lightly and went back an hour or so later and a few of the seedlings had wilted, I’ve left all the windows and doors opened and the greenhouse isn’t getting direct sunlight until around 11am, is there anything else I can do or is it up to the peppers to pull there socks up and survive?

  6. Sylen says:

    I recently, a day or two ago, just transplanted a grouping of coffee shrubs; the pot contained 9 coffee plants. They were pretty root tangled, not root bound yet but close, so there was damage to the roots but the two biggest seem to look droopy and softer then crisp. I’ve given them a few days and one seems be be getting its crisp back but I’m not sure of the other. Is there a chance it could never make it though the transplantation? Or will it take a little time for it to realize it’s not dying?

    • Woody plants are quite tough. Keep the soil moist, but not wet. Keep humidity up if you can. It will form new roots, and provided the plant has enough stored food it will come back. don’t fertilize. Think about cuttings – they have no roots, and yet they survive to make roots and leaves.

  7. cheyenne says:

    I transplanted my small tomato plant and watered it. Overnight the leaves wilted but the stalk seems strong. There are very tiny grey bugs in it also and I don’t know if they are hurting it. What should I do to reverse wilting.?

    • You might have damaged some roots when you transplanted it. With fewer roots, it is having trouble getting water. Give it time and see if it revives itself. The tiny gray bugs may be fungus gnats, in which case I would not worry about them if the plant is outside.

  8. I face a terrible problem with over-watering my plants. I have read that over-watering is not good for the health of plants and I really don’t know where to put a stoppage. Do you have any suggestion for how to check what amount of water is required? Wilt is for lack of water then how to test the water level?

    • Robert Pavlis says:

      Let nature talk to you. Stick your finger in the soil and feel if the soil is dry. Water only when it is really dry. Remember roots go down further than your finger will so when you feel dry soil, it is probably still wet lower down.

      I don’t know your climate, but I hardly ever water garden soil unless we have not had rain for over 10 days. The exception are new plantings that get watered every 3-4 days when first planted, for about a month. After that once a week if it did not rain.

  9. Another thought w/r/t situations where roots are damaged — I’ve frequently read advice to trim a plant’s above-ground parts when transplanting. This reduces the ratio of leaves to roots, and so helps keep the plant in relative balance when the quantity of roots is reduced. Robert, what do you think of this advice?

    • Robert Pavlis says:

      I’ll do a complete post on this in a couple of weeks, but the short answer is that it depends on the plant and the time of year. for woody plants (trees and shrubs) you should never cut the top back when planting.

      If you are transplanting perennials in fall, there is no problem cutting some foliage off. The plant has been growing all summer and building up food reserve. Loosing some leaves will not hurt the plant. The problem with doing this in mid summer is that the plant needs the leaves to produce food to get it through the winter and to build new roots. However, if the leaves will wilt anyway due to the transplanting, there is nothing to gain by leaving the leaves on. In general perennials are tough plants and loosing a few leaves will not kill the plant. If I know that I did a lot of damage to perennial roots, I will cut the plant back on transplanting.

Please let me know what you think - Leave a Reply