Beyond anything else, the most frequently asked houseplant questions are about watering. This is why the first question I addressed in my Garden Center FAQ post had to do with watering. In that post, I answered how often to water houseplants, but I did not specifically address *how* to do it. Let's talk about that now.
(Please note that every gardener and every garden is different. If you have devised your own ways to water and are pleased with your results, then keep doing what you do.)
Use an indoor watering can. While it's true that you can water your houseplants with any vessel that can carry water, a watering can has specific design features that will offer you the most control and ease of use. A watering can intended for houseplants will be light weight and smaller than those intended for outdoor use, typically no more than 2 quarts in capacity. It should have a long spout so that you can pour water directly over the soil's surface without splashing the leaves. The spout should also be narrow, restricting the flow of water so that it pours slowly, giving the soil time to absorb. Most indoor watering cans are made of metal or plastic.
My watering can is shaped like a pink elephant. It makes me smile.
How to use a watering can. Position the spout only a few inches above the soil's surface (beneath the leaves, if possible) and pour slowly. Use a circular motion over the pot or otherwise move the watering can to different locations over the soil's surface and keep it moving as you water. Watering in just one place can cause your houseplant to become both underwatered in some spots and overwatered in others...yes, I've seen it happen! Once you see water start to trickle out of the drainage hole, stop watering.
What if my pot doesn't have a drainage hole? Look, this post is about houseplant gardening for beginners. Planting houseplants directly into non-draining pots is not beginner gardening, so don't do it. Honestly, I don't recommend planting directly into non-draining pots for anyone, regardless of experience level. I will discuss choosing appropriate pots in my next post.
What about ice cubes? I've heard the advice to water succulents, orchids, and other low water houseplants with ice cubes. And it baffles me. The argument in support is that ice melts slowly, so using ice cubes allows you to more easily water these plants slowly. But a watering can does the same thing. Also, we're talking about tropical plants than would never (guess I can't say "never"...who knows what climate change might bring) encounter ice water in Nature. Ice water is 32F, cold enough to shock a tropical plant and cause damage. I say, don't do it.
How to water African violets and cyclamen. Some houseplants hate having their leaves wet and will respond by turning to mush. These plants are best watered from the bottom. Set your pot on top of a deep saucer and pour water directly into the saucer, allowing the pot to drink up the water through the hole in the bottom. You might have to refill the saucer, depending on how dry your plant is. Once the soil surface feels damp, pour out the excess water from the saucer.
How to water air plants. I tend to water air plants by giving them a bath for 20 minutes, once per week, then allowing them to drain upside-down so that no water becomes trapped between the leaves where it could cause rot. I feel like misting them daily with a spray bottle helps to increase the humidity around them, but it doesn't seem sufficient for actually watering them, based on my experience.
Should I be concerned about chlorine in tap water? Generally speaking, I'm not. If you are concerned, leave a bucket of water uncovered overnight and the chlorine will have evaporated off by morning.
Can I use aquarium water to water my houseplants? Yes! Fish poo is natural nitrogen fertilizer, an important part of aquaponic food production systems. Whenever my husband cleans our aquariums and does a partial water change, I ask him to save the water in a bucket for use on houseplants. Freshwater aquariums only, not saltwater.
How can I tell if my houseplant has been overwatered? First, feel the soil. Is it damp? Or is it soggy? How long has it felt that way? If you struggle to answer that one, you're already in trouble. If you see fungus gnats (tiny bugs resembling fruit flies) emerging from the soil, you are overwatering your plant. Mushrooms, mushy leaves, and putrid smells (think of a forgotten bunch of celery in the refrigerator crisper drawer) are all signs of potentially fatal overwatering.
You might be able to rescue an overwatered plant by repotting it with dry potting soil. In the repotting process, inspect the roots and trim off any that show signs of rot. Please know that these rescue attempts do not always succeed. As the saying goes, "an ounce of prevention is worth a pound of cure." To prevent overwatering, know your plant's specific watering needs, have it planted in appropriate potting soil for its needs, only use pots with drainage holes, and always check the soil's moisture level before watering