Elements of plant care: watering
As we've discussed previously, proper light is essential for a healthy plant (go here to read my post on light), and proper watering is equally important. Without light and water, all plants will eventually die. You don't want to overwater the plant and you don't want to underwater the plant - the key is finding the right balance, and that often includes some trial and error if you're a beginner. How often and how much you water a plant completely depends on the plant's own individual needs, it's soil/potting medium, and it's surrounding environmental factors, such as light, humidity, and temperature. The most important piece of advice that I can stress is don't put your plant on a watering schedule. Your plant will probably not do well if you decide upfront to only water it once a week on Sundays, because the environmental factors fluctuate greatly from day to day, season to season.
Before we delve into when and how to water, let's chat quickly about why plants need water. Firstly, water is a vital part of photosynthesis, how plants create their food using sunlight. From the UCSB Science Line, which explains it better than I can: "Water enters a plant's stem and travels up to its leaves, which is where photosynthesis actually takes place. Once in the leaves water evaporates, as the plant exchanges water for carbon dioxide. This process is called transpiration, and it happens through tiny openings in the plant's leaves, called stomata. The water from the leaves evaporates through the stomata, and carbon dioxide enters the stomata, taking the water's place. Plants need this carbon dioxide to make food."
Another interesting fact from the same source: "when plants are not watered properly they wilt. This is because of something called turgor, which is water pressure inside the cells that make up the plant's skeleton. Water enters a plant through its stem and travels up to its leaves. When a plant is properly hydrated, there is enough water pressure to make the leaves strong and sturdy; when a plant doesn't get enough water, the pressure inside the stems and leaves drops and they wilt."
HOW TO TELL IF YOUR PLANT NEEDS WATERED + WHEN TO WATER:
I always hear people say something along the lines of “I wish I knew what my plant was trying to tell me.” Honestly, your plant is almost always trying to tell you what it needs, it’s just in a language you might not understand yet. Your job is to learn this second language so you know what your green friend needs. As stated above, plants will wilt when they’re dehydrated. If you notice your plant looking droopy, with wilted leaves and stems, it’s time to water. The leaves might feel soft or thin, stems will be soft and droop dramatically down. Older bottom leaves might fall, growth might be stunted, and sometimes leaves will curl inward, or brown at the tips if left dry for too long. Of course, the signs to water depend on the plant. Tropical foliage plants will often exhibit the wilting, while succulents, hoyas, and epiphytic cacti will have puckered/wrinkled leaves. Some cacti will even start to rot and shrivel from lack of water for an extended period time!
I typically try to water my plants BEFORE they exhibit signs of dehydration stress mentioned above. Letting plants get droopy and wilted too often can damage the fine feeder roots long term, effecting the overall health of your plant. So, observe your plant and take note of about how long it takes for it to get to the point where it’s dehydrated and try to water before it gets to that stage. For instance, I know that in winter, my tropicals will get wilted in about 7-10 days, so I keep an eye on them and water about every 6-9 days. Same goes for my hoyas: most of them don’t need to be watered but a couple times a month in the winter. In the summer, I water them weekly before they exhibit puckered/shriveled leaves!
Do research on your plant to determine what level of moistness it prefers its potting medium. I’ve mentioned before that there are fantastic groups online - especially Facebook - where you can ask questions in a forum format. I also have a list of reputable books you can reference, found here! These are wonderful resources for discover what a plant needs. At the end of the day, it does come down to trial and error and personal experience.
I have two methods I use for determining if it’s time to water my plants. After I’ve concluded what level of moisture a plant prefers, I stick my finger in the soil to see how dried down the soil is. If my finger is dry, it’s time to water. If my finger is moist, I will wait a couple days. The “finger” method is what I recommend to beginners, although you can also get a moisture meter/reader. I find that they’re not always accurate and it’s best to stick with the finger method! The other practice is picking up the pot and “weighing” it in my hand. Depending on how light or heavy the pot feels determines if I water. This approach I typically recommend to the more experienced houseplant keeper, as it can take some experience to figure out!
Here’s a breakdown of watering needs for me, personally: Flowering plants like African Violets, orchids, and Episcia are kept evenly moist at all times; for my tropical foliage plants, I let the soil dry down about an inch or two; I allow my hoyas and some of my jungle cacti to dry down halfway; and the few cacti I own dry down completely between waterings - especially in winter!
WATERING FROM THE TOP:
Watering with a watering can from the top is probably the most common way to water your plants. Watering your plant by giving it small sips or misting is a sure-fire way to kill your plant - it might not happen right away, but over time it can be deadly. The most effective way to water is to fully soak the potting medium until water comes out of the bottom drainage holes. And yes, using pots with drainage holes is the best practice for keeping healthy houseplants for a long time! I like you use a watering can with a long, slender spout (like the lil' elephant pictured above), because I can control exactly where the water goes. Sometimes I will also places smaller plants in the sink and water them with the sink sprayer, giving their leaves a nice rinse in the process.
If your plant is in a pot with an attached saucer, make sure to tip the pot over a sink or something so that all the excess water drains out! The same goes for if your plant's pot stands on a saucer - make sure to dump out any excess water that's accumulated. Standing water can contribute to root rot, which is a type of mold that destroys a plant's roots, thereby destroying the plant itself.
WATERING FROM THE BOTTOM/IMMERSION:
Some plants don't respond well to watering from the top because they don't like their leaves and crowns staying too wet. Examples of such plants are Saintpaulia species (African Violets) and Gynura aurantiaca (purple passion plant). Simply fill a bowl or dish with tepid water and place the pot in it; the water line should be just below the top of the soil. Leave it to fully saturate (usually takes no more than 30 minutes), and let it fully drain. I use this method for many of my miniature African Violets, and it’s my preferred method for watering a plant that is seriously dehydrated and the soil has caked and pulled away from the sides of the pot. Bottom watering seems to fully saturate the soil much better this way.