The most common cause of houseplant demise is root rot brought on by overwatering—not from too much water, but from watering too frequently.
Plants need a combination of moisture and oxygen available to the root system to thrive. Watering too often and keeping the soil chronically wet deprives the roots of oxygen and leads to root rot, which is usually fatal to the plant.
Unfortunately, there’s no magic formula for how much or how often to water your houseplants. The good news is that once you learn a few basics and start paying attention to your plants’ needs, you should be able to establish a watering routine that will keep you both happy and growing.
Factors That Affect Water Needs
- Plant type
- Light exposure
- Potting medium
Arid/low-water plants: Succulents/Cacti, Hoya, ZZ Plants, Snake Plants, Dracaena, Cast Iron Plants, Bird of Paradise
Moisture-loving plants: many carnivorous plants, ferns, Peace Lily, Alocasia, Calathea/Maranta, Dieffenbachia, Palms, Natal Mahogany Tree (Trichilia emetica)
Most plants use more water and grow most rapidly from March through September, while slowing their growth and water usage from October through February. Although they may be indoors and in a climate-controlled environment, the length, angle, and quality of daylight has more influence over growth than temperature does. Watering during the active growing season may be done almost twice as frequently as it is during the fall and winter months.
The same plant with different lighting will use water at different rates. Growing in brighter light may cause a plant to require more frequent watering than if grown under darker conditions.
Plants in warmer rooms may need watering more frequently, and hanging plants tend to dry out faster than non-hanging plants. Placement such as high on a bookshelf or a ledge may be difficult or inconvenient for frequent watering needs.
Container Type, Size, Drainage & Coverage
Container Type: Different materials used for containers may change the way water evaporates from the planting media—unglazed clay or terra cotta allows moisture to evaporate from the sides of the pot, which is great for cacti and succulents!
Container Size: Young plants in small pots may dry out faster than in larger pots since there is less soil to hold moisture. Newly repotted plants often need to be carefully monitored when watering since the added soil volume may hold excess water.
Drainage: Pots with drainage are essential for long-term plant health. When using a container with no drainage hole, plant into a plastic grower’s pot and insert it into the decorative container to display—remove to water and allow to drip dry before replacing.
Soil Coverage: Any type of soil covering or mulch, such as moss, will slow the evaporation of moisture from the soil and should decrease watering frequency needs.
Indoor humidity levels change from room to room and through the seasons. Using a furnace or other heat source often contributes to low indoor humidity during cooler months. Higher humidity levels are usually found in kitchens and bathrooms. There are ways to increase humidity for indoor plants including pebble trays, glass domes, hand misting, and humidifiers. Generally, plants require less water for their root systems when grown in more humid conditions. However, some plants become susceptible to fungal problems when grown in high humidity or misted too often.
Potting Medium/Soil Type
We sell many different types of potting soils to suit a range of plant preferences, or you can create a custom blend yourself. G&B Palm, Cactus & Citrus Planting Mix has a lot of sand and wood chips for fast drainage while still being able to hold some moisture. G&B Potting Soil has a good amount of peat moss, but is also balanced with enough organic material that it is a nice balance of all purpose soil that neither stays too wet nor dries out too quickly. Baby Bu’s Potting Soil by Malibu Compost is very fine textured and compost-based; it tends to hold water well and is great for moisture-loving plants such as ferns. FoxFarm’s Ocean Forest Potting Soil has extra chunky bits that make for great drainage without being heavy; it is fantastic for most aroids such as Philodendrons and Monsteras.
Most tap water is fine. Ideally, use at room temperature and allow water to stand for a few hours before using to let chlorine dissipate as a gas. If you have a water softener, avoid using it to water your plants, as it can limit plant growth and cause other problems. Filtered, distilled, or collected rainwater are all fine, but not necessary if you have adequate tap water. Occasionally, using water from an aquarium or fish tank (fresh water only) can provide nutrients and act as a mild fertilizer.
During the growing season, you may add a water-soluble fertilizer to the water once or twice each month depending on your plant’s preferences. Always dilute to the proper concentration or weaker, and do not fertilize a plant that is extremely dry without giving it plain water it first (to avoid potential burn).
When to Water & How Much?
Knowing how much to water is pretty easy—water until it runs out of the holes in the bottom of the pot. Plants don’t want to be given tiny sips of water every day or several times each week; fully hydrate the roots and wet the potting soil for each watering, then allow it time to dry out.
To know how often to water, you really should be observant in the beginning and get to know the plant (see above list of plants that prefer to be dry/wet). It is better to err on the dry side than to keep a plant too wet! I have plants in low-light places in my home (ZZ Plant with north exposure) that only get watered about every 4 to 5 weeks in the winter and maybe every 2 weeks in summer.
If possible, keep your plant in a plastic or lightweight pot so you can lift it to gauge how much moisture is in the soil (based on how heavy or light it feels). Especially for smaller potted plants, this is, by far, the easiest technique. Begin with a plant in a plastic pot and get it fully hydrated by allowing it to soak in water for several minutes (see bottom watering below). Remove it after it has become saturated and feels much heavier than it did before—get to know how this feels as it’s freshly watered weight. Check on the plant weekly by lifting it and noting how heavy it feels in relation to that “just watered” weight; water again once it feels significantly lighter.
Using a soil probe to measure the amount of moisture in potting soil. This can also be done by sticking your finger into the soil up to a certain depth.
Physical Plant Clues
As a plant becomes dry, it may display changes in its leaf shape or become slightly droopy—some leaves may begin to roll downward like upside down taco shells or start to sag or wilt. Succulent plants may wrinkle or pucker when their soil has completely dried out as they start to use their own internally stored moisture to survive.
Always be cautious and observant—if a plant appears to be wilting, but it has moist soil, it may be experiencing root rot. Unfortunately, wilting can also be an early sign of overwatering, and therefore, root rot. It is okay to let most plants go extremely dry a few times, however, some plants are less forgiving than others. Once you establish how long between waterings it takes to get so dry, you can ideally create a routine of watering just before that point.
Ways to Water
A watering can with a long, thin spout can help reduce spills and splashing, but usually doesn’t hold much water at one time.
An excellent watering technique that is very thorough is bottom watering. This is done by setting plants into a container with about one inch of water and allowing the water to be soaked up into the soil for several minutes. Some plants, such as African Violets or others with fuzzy foliage, do not like to have wet leaves, so watering from below is the best way to avoid this. Often, when soil has become extremely dry, it may be difficult to rehydrate with a watering can and can best be done by bottom watering.