I usually water my garden in the early morning or later evening, because it’s cooler for me then. But this afternoon, and it’s hot here, I watered mid-day because I hadn’t had time in the morning and they looked like they needed it. But my mom and grandmother always said NOT to water then because it would hurt the plants. Is this true?
According to Neil Sperry, author of Complete Guide to Texas Gardening among others, the best time to water is when your plants need it.The completely dedicated and organized person will anticipate this so that they only water in the mornings and occasionally in the evenings if they are a little out of sync. But for the rest of us, the best time to water is when your plants need it, and when you can fit it in yur schedule.
The main drawback to watering mid-day is the amount of water lost to eveporation. In some circumstances evening watering can encourage certain diseases in some plants.
So water away.
Thanks for the help! The tops of the tomato plants were looking kinda droopy, so I decided to go for it.
Aside from the water loss due to evaporation, you also risk burning your plants when the water evaporates so quickly in the hot midday sun that it is drawn out of the leaves and they scorch.
Tomatoes prefer a deep weekly watering to a daily shallow one. It helps them develop deeper roots.
If you find that you must water frequently to keep your garden happy, I strongly suggest investing in a drip irrigation system. Drip hoses are covered in tiny holes that allow the water to slowly seep through. You wind it around your plantings and cover it with mulch. There is almost no loss to evaporation and you don’t risk burning the leaves. And you don’t have to stand there holding the hose. You can even buy timers so you can turn it on for a couple hours at a time even if you are away.
The best time to water is late evening or night time. Water has a much better chance of becoming fully bound in the soil before evepaorating and so is more efficiently used. Aside from that I can’t think of any reason not to water in the middle of the day.
With all due respect, this sounds like an old wives tale. I can’t see any way this could happen. Do you have a cite?
One of my gardening books says that the old adage about “not watering in the middle of a hot, sunny day or you’ll burn your plants” is related to a belief that the water droplets on the leaves will act like a magnifying glass. The author thought this was probably not true, but went on to note that rapid evaporation could possibly leave a mineral residue (salt, mainly) that could burn leaves. Whether or not that’s credible, it’s the water loss issue that is a much better argument for watering in the morning or evening.
Also, wilting during the middle of the day might be normal for some plants. If they bounce back at night, they’re not stressed. It’s when they look wilted in the a.m. or p.m. that they’re probably screaming for water.
I’ve heard that if you water in the evening, the water stays on the grass too long and can promote fungus. The way to avoid this is to water before dawn so the water will evaporate after the sun rises.
Again, thanks to all who have replied.
“One of my gardening books says that the old adage about “not watering in the middle of a hot, sunny day or you’ll burn your plants” is related to a belief that the water droplets on the leaves will act like a magnifying glass. The author thought this was probably not true, but went on to note that rapid evaporation could possibly leave a mineral residue (salt, mainly) that could burn leaves. Whether or not that’s credible, it’s the water loss issue that is a much better argument for watering in the morning or evening.”
So the little magnifying glasses are a myth and the salt residue could only be problem if you had REALLY hard water. But why water the leaves at all? That’s not only an enormous waste since it wont do the plants much good but is also just asking for fungus problems. Water the ground where the roots are. If you give the roots of tomato plants infrequent, deep waterings, they will put down roots many feet long and by they time they start bearing fruit they should be able to go for long periods without water.
“I’ve heard that if you water in the evening, the water stays on the grass too long and can promote fungus. The way to avoid this is to water before dawn so the water will evaporate after the sun rises.”
Another way of looking at this is that since wet blades are promote fungus, the best time to water is when the grass is already wet anyway which means anytime it has dew on it which means, in most places, anytime between maybe 2 am and dawn. Some experts suggest watering “in the evening” figuring that avoiding a few extra hours of damp before the dew starts to settle does not justify staying up half the night (for people without timers on their irrigation systems).
Thanks Cranky. That sounds more plasusible than the water being drawn out of the leaves. The problem with this theory is that water evaporating slowly from leaves at low temperatures would leave just as much, if not slightly more, salt residue as water evaporating at high temperatures. The problem is one of water pooling on the leaves, not temperature or time of day.
Watering in midday tends to cause the plant to further open the pores (stoma) in the leaves. This means water will evaporate out of the leaves quicker. I would imagine that water on the leaves could cause moisture to wick out through the stoma the same way as the water on the leaves evaporates which may cause the scorching problems mentioned earlier. That said, if your plant is wilting in the midday sun, you’ll do much more harm by not watering it than whatever harm you might do by watering it. Watering in the morning is best because it gives the plant time to absorb moisture while the air is cooler. Watering in the evening leaves the issue of the plants remaining wet all night long and gives fungi a chance to develop on the leaves. This is especially true of fungi prone plants such as roses.
Stomatal aperture is dependant on water pressure within the guard cells, not water pressure in the rooots. Watering will not cause the stomata to open further, having sufficent water will do that irrespective of when the water is applied. If the stomata are closed the plant is not utilising either sunlight or soil nutrients efficiently and is not growing as well as it could. Water won’t evaporate out quicker as a result of watering, only as a rsult of having sufficient water. Stomata are located primarily on the underside of leaves, so water droplets are unlikely to have any contact with stomata. Water on the leaves couldn’t cause water to ‘wick out’, water evaporates via stomata as a normal process of plant physiology.
I apologize for not responding sooner. I volunteered my gardens as part of an organic garden tour yesterday so I was outside all day.
I freely admit that concept of leaf burn due to midday watering is merely handed-down advice based on no scientific study. I guess if the wicking out of water from the leaves doesn’t actually occur, then the curling and browning of leaves is likely to be the result of inefficient watering techniques that leave the plants with much less usable water than the gardener thinks he is giving them. In other words, you go out and sprinkle a bunch of water on the plants, which is mostly evaporated, and your plants are still water-deprived, even though you think you watered them sufficiently.
Water when it’s needed but…
If you water in the heat of the afternoon a good deal of that water will be lost to evaporation and you can damage your plants. My theory is that those water droplets that remain on the leaves can get so heated by the sun they kill whatever plant tissue they are in contact with. Grass can be very prone to this and I will try and find a cite.
If you water in the evening the plants will not be able to use the water immediately as they do not photosynthesize in the dark. The water will sit and do more to encourage the growth of fungus and moss than help your plants.
This leaves us morning as the best time to water. Most of the water on the leaves will run off or evaporate slowly as the temperature rises. Your plants will get to start their day with a good drink of water and love you for it.