Plant watering is often the hardest subject to teach. Overwatering, underwatering or getting it just right can be as hard as Goldilocks finding the right bed. The best time to water plants cannot be set by the calendar or clock, so let’s see when it is.
The Best Type of Water for Plant Growth
Let’s start with some basics. Not all water is created equally and some may not be as beneficial to your plants as others. There are many options available: rainwater, bottled spring water, tap water, and distilled water, just to name a few.
You have probably noticed how much better your plants grow when there has been sufficient rainfall. As you may know, the air is 78% nitrogen and nitrogen is one of the most important elements involved in plant growth. When it rains, a part of the nitrogen ends up in the ground where it’s then easily absorbed by plants through the roots and leaves.
Another benefit of rainwater is that it also contains more oxygen. Thanks to the fact that rainwater is highly oxygenated your plants won’t suffer from root rot, even if there are extensive rain events.
When rainwater combines with carbon dioxide and other minerals present in the air, it becomes slightly acidic, and once it touches the soil, it helps to release important nutrients for plant growth like manganese, copper, zinc, and iron.
As a final note on rainwater, collection in barrels is not just about saving water but will offer you a great (free) reserve of excellent quality water for later.
Disclaimer: Rainwater harvesting is illegal in some states.
2. Bottled Spring Water
While this option is usually way too expensive for outdoor use, your houseplants will benefit from it immensely.
Bottled spring water contains natural minerals which are needed for growth in plants. Due to the fact that spring water runs over rocks and different objects, it gets oxygenated and becomes rich in minerals.
So, while not as good as rainwater, bottled spring water rates a very high second.
3. Tap Water
Depending on what part of the world you live in, your tap water is completely useable for your plants. It is the go-to choice if you do not collect rainwater and just run irrigation or water using a garden hose.
The drinking water systems usually contain chemicals like chlorine, fluorine, and sodium. While these chemicals may not harm your plants, in small amounts, they can prevent the plants from reaching their full potential.
Before using tap water, make sure that your plant is not prone to chlorine or fluoride toxicity.
4. Distilled Water
This is the worst of the four types of water I have listed here. Perfectly distilled water ends up with a pH of 7, which is neutral. Plants prefer some acidity, usually 6.8 or lower.
Distilling water takes everything out of it, including bacteria, organic chemicals, inorganic chemicals, heavy metals, and other contaminants, thus leaving you with very close to pure water. However, just because it is pure, it still has literally nothing in it.
When is the Best Time to Water Plants?
There is a lot of debate as to when is the best time to water plants.
The short answer is: When they need it.
But how do you know?
Watering Plants in the Morning
Early morning is the best time to water your plants, while the air temperature is still cool. Watering in the morning will help the plants throughout the day, as they are starting out with a full moisture level and that will allow them to deal better with the heat of the sun.
Of course, you will need to learn your plants’ needs and the soil type that they are growing in. If you water the plants early in the morning and they are struggling by late afternoon, you should consider changing the watering hours.
Watering Plants in the Afternoon
So, your plants are really struggling by this time of the day and you have been watering faithfully every morning. Late afternoon is your next best time to water. This gets trickier during different parts of the year. You want to make sure that the leaves have a chance to dry off before night falls.
Watering your plants at this time of the day has its benefits: the plants will be able to absorb more water without the intensity of the afternoon sun and it cuts down on the loss of water due to evaporation.
Watering Plants in the Middle of the Day
There is a myth that needs to be dispelled once and for all. It goes like this: if you wait until noon or mid-afternoon when the sun is very hot, watering can burn the plants. The sun-heated water will get too hot and burn the plants’ stems and leaves.
It is simply not true!
There are very few areas in the world that get intense enough sun for water droplets to burn or scorch your plants’ leaves. Also, in an area where the sun does get that intense, the water would evaporate long before it could cause any harm.
Now, the reason why the middle of the day is not the best time to water plants is that you are going to lose a lot of water due to evaporation. Plus, it is hot out there and I doubt you want to be standing in the sun.
Watering Plants at Night
This is the worst time to be watering your plants. When you water at night, the water sits on the leaves and stems of the plants instead of evaporating. Then, the nighttime temperatures drop and condensation or dew sets in, adding even more moisture to those leaves. Your leaves will now be wet for anywhere from 10-12 hours.
Those damp leaves at night encourage fungus problems, such as powdery mildew or sooty mold.
If you absolutely must water at night, due to your time schedule or municipality rules governing the use of horticultural watering at night, then see if you can install a drip irrigation system. The leaves will not get wet this way.
Signs of Overwatering and Underwatering
Plants should never be allowed to stress for water. It will stunt their growth and, when it comes to fruiting plants, it will cause the fruit to be smaller than advertised. When a plant is stressed for water it will rob that fruit of moisture to make sure the plant survives.
Plants will often show the same types of signs for both over and underwatering. Plants that are getting too much water are just as likely to die as plants that get too little water.
Here are a few overwatering signs: leaves that are yellow or brownish at the tips, limp, soggy foliage, and signs of rot.
When it comes to underwatering, you might want to look for: leaves that are yellow or brownish at the tips, wilting, dry leaves, and general lackluster appearance.
Both of these situations should be avoided.
Leaves of a lemon tree that is in desperate need of water
If you are unsure as to which it might be, consider keeping a journal of when you water. If you are watering every day and they are limp, it could be a sign of too much. Back off a day or two and see what happens. If you only water every other day and they wilt, try watering every day and see if that helps.
How to Water Plants
There are a few factors to keep in mind before starting to water your plants.
The Plant Variety
The first one is the plant variety. There could be an entire article written on the different moisture levels needed for different plants.
The best advice I can give you is, research and get to know your plant’s needs. If your houseplant is originally from a desert region of the world (succulents and cacti), you can imagine it needs far less moisture than one from a rainforest.
A favorite story I have told is about a woman that was growing Cacti in the Northeastern part of the United States, not exactly desert terrain. She had some of the most beautiful, huge, cacti that anyone has ever seen. What were her watering secrets? She watched the newspaper and when they predicted rain in Arizona, she watered hers. No other times.
A happy cactus NOT growing in Arizona
The Soil Type
Soil types will play a huge role in the amount of and when is the best time to water your plants. Another gardening myth I want to dispel goes like this, “X plant needs one inch of water per week”. That one drives me crazy.
Sandy soil tends to drain water rapidly, thus it will not last for very long. Heavy clay or peat-based soil will not drain rapidly and, depending on the atmospheric conditions, it may hold water for a long period of time.
In the yard, a low-lying area may hold water much longer than a raised bed will.
The Container Type
Container plants will dry out much faster than their in-ground counterparts. Plastic pots retain moisture better than terracotta or clay pots. Do you understand now why I am not fond of that one inch per week sentence?
There are many different water measuring meters on the market, and there may be some good ones that actually are reliable. Out of the dozen or so that I have had, I have never found them to be so. However, you have a moisture meter on your body right now, your finger. If you stick your finger into the soil and it is dry up to your second knuckle, there is a pretty good chance that your plant really needs to be watered.
The situation that you are in will also determine the best method for watering your plants. Some folks like to set them in a pan of water and let them soak the water up. Others make sure not to get the leaves wet at all, such is the case of African Violets, they really don’t like that much.
Check out this video from Helpful DIY to see how the “Finger Method” works:
How to Water Plants While Away
I know that many plant folks wish they could take their plants with them on vacation, but, sadly, it is not always possible. If you are only going to be gone for 2 or 3 days, water your plants as much as you can just before you leave. They may not be as pretty when you get back, but they should still be alive.
If there are going to be more than three days and you do not have a responsible neighbor or family member that can help you out, there are a lot of products on the market for houseplants, like this self-watering globe, that, depending on circumstances, can keep them alive for a week or more.
Investing in well-designed self-watering planters can be another great solution, as they can drastically reduce your plant’s watering needs.
As you can see there are many variables on how and when the best time to water plants is. No article will be able to tell you exactly when your plants need water. Experience is the best teacher.
If you ask a dozen people how they know when is the best time to water plants, you will get a dozen different responses.
Let us know what is your favorite method, as we would love to hear what works and what doesn’t for you and your plants.