Plant Watering 101

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The (Very Introductory) Science of Plant Watering

The rarest material in the known galaxy isn’t diamonds, gold, helium, or even neodymium. It’s plant matter. Wood, leaves, flowers, things that don’t exist anywhere else in the known universe, things that make all life on earth possible. Of course, you don’t get plants without another rare ingredient: liquid water.

plants with a watering can

Between 80%-90% of a plant’s volume is made up of water. But why do plants need water? Plant cells use water to remain rigid and upright. The water that they take in through their roots is distributed throughout the plant, but if the roots are dry, the plant will move water from the leaves to other places, which creates the wilting effect you’re probably familiar with.

Why do we have to keep watering our plants? Because plants recycle more than 90% of their water back into vapor, through a process called transpiration.

If water is so important to plants, why is it so hard to water them the right way? Despite being one of the most basic aspects of plant care, watering is a constant challenge for fresh-faced plant parents and hardened garden veterans alike. This is largely due to the fact that plants evolved to exist in very specific climates and conditions. We’re most likely to raise healthy plants when we’re able to recreate some of the key aspects of their native habitat. This means paying attention to light—how much your plant needs, whether it prefers direct or indirect light—as well as soil, temperature, and of course, water.


Tips for Successful Watering

While some plants are easy to care for and can go months between waterings, others can be downright finicky. It’s important to research your plant’s needs, preferably before bringing them home. Like any relationship, it won’t matter how beautiful the plant is if we can’t meet all of its needs. (Wow, too real?)

Below are the main pieces to be aware of when it comes to watering.

pink planter

Choose the Right Container

Containers for houseplants come in an infinite array of sizes, shapes, and styles. But when it comes to picking the right container for your plant, you’ll likely hear every plant blogger and greenhouse guru recommend a pot with built-in drainage holes. Drainage holes are a lifesaver for your plants. They give the water an escape route, which keeps your soil from
becoming too saturated.

The problem with soil saturation is that it produces the perfect environment for bacterial growth and disease, including the infamous ‘root-rot.’ In this hyper-moist, oxygen-deprived environment, your plants won’t be able to breathe and can literally drown. A drainage hole helps prevent this buildup of moisture and makes it easier to judge when your plant is thirsty.

The size of the container also plays a role in watering. Larger pots tend to dry out faster than smaller ones, and hanging planters often dry faster than those at ground-level, due to higher temperatures near the ceiling.

Potting soil mix

Keep an Eye on the Soil

Many plants prefer specific kinds of potting mix. Some mixes include amendments that will increase moisture retention, such as perlite, while others, like vermiculite, increase aeration and allow the soil to dry out more quickly.

Matching your potting medium to your specific plant’s needs is always a great way to ensure the prolonged health of your plant. This is especially true of succulents and cacti, which prefer to have their soil dry out completely between waterings, and many tropical plants or ferns, which like to stay a little damp all the time.

When it comes to soil maintenance, one of the most important things to watch out for is soil compacting. If your soil becomes too dry and compacted, the water will simply run out of the drainage holes and not absorb into the soil. In these cases, it’s recommended to soak your plant, either with repeated short waterings or by filling a tray or saucer with water and allowing the soil to wick the moisture upward.

If the soil becomes compacted, try gently breaking it up with your fingers or a pair of chopsticks, or consider repotting with fresh soil.

Monstera Deliciosa

Mind the Season

Most plants are significantly more active in the summer, and will therefore need more regular waterings. This is the time of year when most plants put up new growth, but increased sunlight and temperature also mean that soil dries out more quickly. Be sure to check on your plants more regularly in the summer than you might otherwise to make sure they’re not
getting too thirsty.

Conversely, plants tend to conserve their energy in the winter. Usually, this means that they need significantly less water than at other times. Be sure to adjust your watering schedule accordingly.

watering the houseplant

How to Water

While plants are relatively easy to please when it comes to what kind of water to use, it’s often recommended to avoid using softened water whenever possible, because the salt content is higher than most plants prefer. Chlorinated tap water is usually safe, but if you have access to filtered water, that’s even better.

Most houseplants prefer tepid or warm water to cold, as cold water can shock the plant’s system. One way to stay ahead of the game is by filling your watering can immediately after watering, so that it’s perfectly room temperature next time you need it. This also gives an opportunity for other chemicals present in treated water to evaporate out.

When watering, be sure to water all sides of the pot evenly and thoroughly. Your plant’s roots are much deeper than the surface, which means that you’ll need to penetrate past the first few inches of soil. Add water until it begins to fill the saucer or tray underneath, but don’t let the water sit for more than ten minutes afterward, as this can leave your plant vulnerable to disease.

Alternatively, you can fill the saucer directly and allow the soil to pull the moisture in from the bottom. This is preferable for plants that prefer to keep their stems dry, such as succulents, cacti, and orchids.

How to Tell if your Plants Need Water

By far the easiest way to gauge whether your plants need water is ye olde finger trick. Simply push your finger down about two inches into the soil. If you detect any moisture, your plant probably doesn’t need water. If it feels dry all the way down, go ahead and give them a drink!

Watering schedules are an excellent way to make watering easier on you and your plants, but because different plants require water at different intervals, you may have to tweak it along the way. Remember that watering does get easier over time, and the more attentively you do it, the more quickly you’ll develop an instinct for it.

Watch out for Overwatering

The two easiest ways to kill a plant are over-watering and under-watering. Shockingly, over-watering kills more houseplants than complete neglect. While plants need water to survive, like the rest of us, they can have too much of a good thing.

Signs of overwatering include stunted growth, yellowing leaves, and at worst, root rot.

It’s helpful to know that just because a plant has been overwatered doesn’t mean it’s doomed. The majority of plants are resilient enough that they can make a comeback. If you think that your plant is experiencing root rot, there are some solutions out there, including manually removing
infected areas, and refreshing the soil in the container. For more information on overwatering, check out this article!

Thanks for reading! Be sure to share your plant journey with us @houseofplantlovers.

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