One of the most frequently asked questions we get here at Crimson is “How often should I water my plant?”
Our answer is always “That Depends!” There are many factors that go into when and how you should water your potted houseplant and today we are going to cover the basics.
Here are the factors that affect how much water your plant is using: Sunlight, air temperature, air flow, type of soil mixture, type of planter, type of plant, day length and root mass. We covered the planter options and soil mixtures in our first post on how to repot your plant. Given that previous information we will assume you have a good pot and soil combo for your houseplant; this is really the key to setting up a successful watering regimen. Next up is sunlight: plants use sunlight, carbon dioxide, and water to make sugar, this means that when the sun is shining your plant is using water to make sugar. Therefore the more light the more water your plant is using. More light also usually means warmer temperatures. When it is warmer water is lost from the soil by evaporation. Evaporation can be further increased if there is a lot of air movement. So in general if you have a lot of light, high temperatures and a lot of air flow your soil will be drying out quite quickly and you will need to check on your plant more often.
Exactly how often you should be checking your plant depends most on the type of plant that you have. Most houseplants fall into the following categories:
“Moisture Loving” check every 2-3 days: These plants are plants that want to stay WET. There are even some plants that fall into this category can be left sitting is a dish of water and thus all you need to do is refill the dish when dry. These plants you are checking frequently to ensure that the soil only ever becomes dry to the touch on the very top. For these plants it is best to keep them on moist side rather than letting them dry out. Some examples of plants in the this category are Bog carnivorous plants, maidenhair ferns, corkscrew rush, Aphelandras (zebra plants) and more.
“Evenly Moist” check every 4-7 days: These are the plants that are usually described as wanting to stay “evenly moist.” These plants generally want their soil to be moist but not saturated. The best way to achieve this is to water your plant thoroughly and then let it dry down over the course of about a week and when the top 1-2 inches of soil is nice and dry then it is time to water again. This cycle mimics a more temperate water cycle where it rains once or twice a week with time for the soil to dry a bit in between. Some examples of plants in the this category are most Ficuses, rabbits foot and blue star ferns, Diefenbachia, Aglonemas, and more.
”Dry Adapted” check every 7-14 days: These are the plants that are very susceptible to root rot and thus they want their soil to dry out very well between waterings. Most of these plants are from xeric habitats or seasonally dry habitats; thus it is very important that you are sure the soil is dry quite far down through the pot before you water them. Some examples of plants in the this category are cacti, succulents, euphorbia, sansevieria, ceropegia, senecios and more.
Now that you know when to water your houseplant the final question is how do you water your plant. Most houseplants prefer a thorough watering to ensure that all the soil is moistened and no dry spots are left behind. If you think of your soil like a sponge there is a finite amount of water that that sponge can hold at one time. This is why it is important to have a drainage hole in your pot. This allows to completely fill your “sponge” up knowing that any extra will drain out the bottom.
In order to accomplish a thorough watering we recommend the following steps:
1. Set your planter in a dish or saucer (it is advisable to do so in a sink or tub in case of saucer overflow).
2. Fill the pot to the brim with water and let it soak through. Repeat this 3-4 times until you havewater collecting in the dish.
3. Let your plant soak for 20-30 minutes (this ensures all dry patches inside the soil get a chance to fully moisten).
4. Empty the extra water from the saucer and let any other excess water drain from the pot.
For your dry adapted plants we recommend watering by a soil rinse. To accomplish this type of watering do everything you would for the thorough watering but skip step #3. This will allow your soil to remoisten and also rinse any excess salts or fertilizer out while not fully saturating all of your soil. Keep in mind that in the midst of a hot spell or a long succession of really sunny days even dry adapted plants may need a thorough watering to rehydrate and ensure that their soil doesn’t get so dry that it becomes hydrophobic.
A soil rinse is also a watering trick you can use on your evenly moist plants if you are growing them in the lower levels of their light tolerance or if your evenly moist plants are potted in a soil that stays too wet and you aren’t ready to repot them yet.
Finally, your watering schedule can change over time due to the final factors affecting your plant’s water use: day length and root mass. As seasons change so does the day length which leads to your plant receiving much less light on a daily basis, this means they are using much less water and you’ll have to adjust your watering schedule accordingly. You may find over time that your soil starts to dry out faster and faster even though the light, temperature and airflow seem to be the same; often times this is a sign that your plant has begun to outgrow it’s pot. The pot becomes so full of roots that the soil becomes compressed and can’t hold as much water as it used to. Essentially your sponge has gotten smaller. If you notice your plant is drying out much too quickly it is time to repot!