Plants are living entities and need water to stay alive, just like Aubrey II in the Little Shop of Horrors. But unlike the bloodthirsty, nerve-shingling plant food of human blood, real plants just need water to grow healthily strong, to like, you know, stave off zombie fright nights.
Now, you might not be one for drinking water without the flavoring but you do drink something.It’s needed for biology to do its thing. In the plant kingdom, biology works differently from how our bodies use water.
When we hydrate, we pee. When plants are hydrated, they store it only during the day and then it evaporates during the night. That’s called plant transpiration and it’s the reason for dew being on your plants in the morning.
Do you know why plants get morning dew?
It’s because when you water your plant, there’s a whole transport system in there that the plant uses to carry water up from the roots, through the stem and into the leaves. Up to 90% of a plant’s entire weight is pure water content stored within the cell walls. Much of it stored in the leaves themselves.
That’s where the neat stuff happens. During the day it’ll stay there because photosynthesis can only happen during the day when there’s sufficient light. When the lights go out, the water then evaporates through the leaf nodes creating carbon dioxide.
Know what else?
You know the way plants wilt (or how the starving ones do at least)? That happens to plants because the water stored in the plant is what makes it stand up all on its own.
When it comes to plant watering, it’s like everything else you know you should do but don’t prioritize because you don’t have a strong enough reason to. Think of these as your reasons to get “water the plants” onto your to-do list.
Gathered below are the top 7 questions about watering plants, covering things like why plants need water, how to know if they’re getting too much, the types and sources of water that’s best and more…
Time to learn a few things.
Top 7 Plant Watering FAQs
1 – Why do Plants Need Water?
Skipped all the reasons above (TL;DR – Too Long; Didn’t Read)?
Here’s the bitesize list:
- Plants need water to create food. During the day, photosynthesis happens and it’s when plants create the sugar.
- Water’s also a liquid diet for the plant. It’ll move all the nutrients, minerals and other substances the plant needs throughout the entire plant so there’s no dying leaves or wilting stems. The whole plant gets fed.
- For a plant to stand, it needs turgidity and that’s impossible with low to no water. The water stored in the cell walls during the day is why the plant can stand up and not bow out of life.
- At night, when it’s lights out, the water will have served it’s purpose by reaching the leaves after traveling around the plant. It then escapes through the leaf nodes and releases carbon dioxide. That’s the plant transpiration phrase and it’s also a necessity for temperature control. Transpiration is just a plant’s way of sweating to cool down.
In a nutshell, the plant would have zero nourishment for anything to happen without water. If a real plant can’t get water, it’ll wither and die. Some will live longer than others but eventually, it will be game over.
2 – How Much Water Do Plants Need?
The amount of water a plant needs varies and it’s notoriously difficult to put an exact ml amount to any plant. The needs will change by the day because of things like temperature fluctuations, humidity, where you have the plant located, the plant’s age, the compactness of the root system and the native region the plant is from.
The good news is, there’s a neat trick you can use to get a good guesstimate of the amount of water your plant needs.
- The next time you water your plant, give it a thorough watering and then weigh it.
- Then leave it for 24 hours and weigh it again.
- Now you’ll have two numbers. One just after it’s been watered, the other when it’s used the water. The difference between those two numbers is the amount your plant used for its 24-hour watering cycle. You’ll need to replace that amount of water at a minimum to avoid under-watering and prevent dangerous over-watering too as that can kill plants.
Do the above for a few feeds and you’ll find an ideal amount of water to be feeding your plant. Not too much to drown it nor too little to have any impact. Just a very close measurement telling you how much water your plant needs at a minimum.
3 – How Will I Know When I Need to Water or Air the Plant?
Plant language isn’t very subtle but it’ll get easier as your eyes get trained on the signs to look for.
When they’re in need of watering, the first thing you’ll notice is that they’ll lose shape. The water content isn’t enough in the cell tissue and walls of the plant for it to stand up as it should be. Instead, you’ll have a plant that’s wilting over because the skeleton strength won’t be there to help it stay upright.
That’s only a possibility though because, over-watering can cause the same effect.
For soil plants, the answer is simple:
- If the soil is wet and the leaves are wilting, there’s too much water.
- If the soil is dry to the touch and the plant is wilting, there’s not enough water.
If there’s too much, you need to air the plant or give it a little sunlight to help dry it out. Not too much as you don’t want to swap an over-watering problem to a leaf burn problem.
If it’s the latter and it needs water, well, water it. What’s more to say.
4 – What’s the Best Water Type for Plant Growth?
That’d be a handy tidbit to know – don’t you think?
The best water is rainwater…
Tap water can work, provided it’s left overnight to dechlorinate and get rid of any other contaminates in the water. However, there are no extra nutrients in tap water, nor does distilled water have any benefits for plants.
The best type of water to use for all plants is always rainwater so it’s worth finding a container to collect some in.
Here’s the thing to remember though…
Rainwater has nutrients already so if you’re going to be using a water-soluble fertilizer to help nourish your plants a bit more, go real easy on the volumes. Preferable to using fertilizer is to use distilled or purified tap water with the fertilizer and rainwater for the rest of the feeding times.
Here’s a few reasons why rainwater beats every water type:
- It’s 100% soft water and chemical-free
- It has the lowest pH levels of any type of water because there’s no delivery system needing treatment to prevent pipes from rusting and corroding. That’s why tap water leans towards the alkaline side of the pH scale. Rainwater, as any organic gardener will tell you, is nature’s water. Can’t get any better.
- Nitrates are a macronutrient that plants need for growth. It’s part of the reason plants love rainwater, but the best time to get more nitrates is in the rain right after a thunderstorm.
“Rain, rain, go away. Spare your nitrogen for another day.”
~ Dr. Mark Lorch – ScienceFocus.com
For the love of all that’s holy though, when you collect the rainwater, let it reach room temperature. Don’t freeze your plant with just defrosted snowflakes.
You don’t want to use fertilizer with rainwater either because those will have another dose of macro nutrients, which could be a little too much. Nitrogen is only one of many macronutrients a plant needs.
The others are calcium, potassium, magnesium, sulfur and phosphorus. That’s where fertilizers come into the equation.
Before diving into fertilizers though, know that while water may be abundant around you, you can’t just take water from any source and expect it to work like magic because it’ll hydrate your plant.
Water’s not just a drink for plants. It’s their entire nourishment.
5 – What Are the Different Sources of Water for Plants?
Of all the types of water you can find, there are really only three sources to get all that water from.
- Surface water (lakes, rivers, streams and ponds)
- Ground water (found beneath soil and between rock crevices)
It’s worth mentioning that bottled water is either treated tap water or spring water. Estimates for the U.S. bottled water sources are 55% are spring water, while the other 45% treated tap water. That’s not great when a spell of drought kicks in.
Then again, rainwater is out of the question, so tap water’s the only option remaining, and even that’s not an unlimited supply. The way to go about watering plants during a dry spell of water is to recycle what you’re using.
Pour away nothing.
Here’s a video with two foolproof ways to use the water you’re already using to water your plants. This is for outdoor plants, but it’ll work for indoors too. Just be sure to let the water sit for 24-hours for the water to detoxify itself of fluoride and chloride.
6 – Is there a Way to Improve Water Quality?
There sure is. The easiest of all is to decorate with your windowsill with two or three small glass jars with only water in them to be used for your plants. That way, you aren’t taking water straight from the tap and potentially harming your plants with chlorine and other contaminates. They’ll evaporate.
So, feeding your plants with purified water is an improvement. Keep a few small jars of tap water and you’ll have a fresh supply at the ready.
Another improvement, albeit a rather complex, time consuming and probably expensive option is to build yourself a mini rain garden. Although, you’d probably need a course or hire a pro to build you up a genius rain garden.
Just look what’s involved…
A bit much?
Let’s talk fertilizers then because purified water is the next best thing to rainwater, just with zero nutrients. That’s only going to hydrate your plants. They’ll be self-reliant and have to make their own food. They will do that when they have the right amount of water, but to really help them grow, that’s where fertilizers come in.
Fertilizers are the only way to add macronutrients into the plant’s natural feeding system. The water will then carry all those throughout the plant, helping it grow, flower, and fend off common plant diseases and other problems.
Most plants will need this additional plant food around once a month. It can be extended to 6-weekly cycles. There are certain plants that do not need fertilizer at all though so always do your research and make sure the ingredients have nothing that can harm your plant, such as traces of copper.
7 – How Do Different Types of Water Affect Plant Growth?
The type and quality of the water can have a massive effect on your plants. It can completely revive a dying plant, or have the reverse effect on a healthy plant if the water quality deteriorates.
One thing to always remember is there’s only macronutrients in rainwater. Others are only plain water with no beneficial additional extras. Just the chlorine and fluoride contaminating tap water that can have a detrimental effect on plants.
If not, then it certainly won’t deliver any extra nourishment. Only rainwater can do that because it’s got a high amount of nitrogen gas, or if it’s storm water, it’ll have the gases broken down into nitrate making it easier for the plant to absorb.
Growing up with a mom who filled her home (inside and out) with all sorts of plants, Lisa got her start in gardening at a young age. Living now on her own with a home and yard full of plants (including an indoor greenhouse), she shares all the gardening tips she’s gained over the years.