This is a post for everyone, the under-waterers & the over-waterers, and those who think they got it down.
Watering seems to one of the main challenges for most plant parents, how often? how much? Hopefully this post will give you a head start in the right direction.
Why is watering so important?
Just like us, plants need water to survive, its essential to life.
Plants can be compared to giant straws, sucking up water and nutrients through their roots and into their stems and leaves. Within each plant are tiny vacuoles which are cells that hold water & nutrients and remove waste. Roughly 60-80% of total cell volume is filled with water. In herbaceous plants, vacuoles are important for maintaining the turgidity of the plant; when the vacuole pressure is used up, the plant goes limp – you may notice this with your begonia or peace lily in your home.
What is transpiration?
Transpiration is evaporation of water from the aerial parts of the plant or any part of the plant with stomata. Most of the water that the plant takes up from its roots is released via transpiration into the atmosphere.
All water actions are passive & transpiration can happen independently to photosynthesis.
The higher the rate of transpiration the more frequently you’ll need to water your plants.
Transpiration rate is dependant on several factors, the 3 main being:
If you place your plant in low light, the rate of transpiration drops, plants which receive full or ample sunlight will have a higher rate of transpiration. Sunlight affects the rate of soil water evaporation and forces the stomata on the plant to open, releasing water. Transpiration only happens during the day as the stomata are closed at night.
The higher the humidity the lower rate of transpiration & vice versa. Its easier for water to evaporate into a lower pressure (low humidity) atmosphere, than it is to evaporate into saturated air (high humidity).
Higher air movements around the plant increases the rate of transpiration. Saturated air around the plant is moved around and replaced by drier air, wicking away water from the plants surfaces.
Top vs Bottom
I’m a strong believer in top watering. This is the natural process that plants are accustomed to, so why change it?
However, that’s not to say that I don’t bottom water from time to time too.
Top watering allows you to get an even drench on the soil, and an easy way to do this is to take your plant to the sink, put them under a slow running tap, and let the water drain out the bottom of the pot for several minutes. This allows the salts and minerals to run off, reducing build up, and for water to evenly saturate the soil/growing medium.
Bottom watering is good for plants planted in sphagnum moss, which quickly & easily absorbs water. Plants potted in orchid bark, charcoal or clay based potting mixes, don’t tend to work well with bottom watering, as water absorption is slow or inadequate. Bottom watering also doesn’t wash away any salt or mineral buildup.
The pot you use will affect how often you need to water.
Plastic vs Terracotta
Which is better?
Depends. If you’re an over-waterer, best go with terracotta, to avoid root rot. If you’re an under-waterer, plastic will keep moisture longer, giving you a few days lenience if you forget.
The medium you plant in will directly affect how much you need to water your plant.
Different soils/mediums hold water and moisture differently, and its important to know which is the right one to use. For example:
Moisture-loving plants (alocasia, caladium, ferns etc) do well in a peat based potting mix.
Succulent and cacti do better in a potting soil /sand/perlite mix.
Common mistakes & fixes
What to do?
Medium – Do some research into the plant you have and the soil mix you’re using. More often than not, people plant the wrong plant in the wrong soil mixture.
Where is your plant located? If your plant is in lower light, the rate of transpiration will be lower and watering should be less frequent. In higher light, the opposite applies.
Ensure your plants get the right amount of light to thrive, not just survive.
Root rot? Check your plant for root rot if you see any of the signs from the diagram above. Remove the plant from the pot and cut off any brown or soggy roots (healthy roots should look similar to ramen noodles), and repot in the appropriate soil.
Crispy tips? This is usually said to be due to low humidity, which may be true in some instances, but it can also be due to a build up of salt in the soil and the water type used. To avoid crispy tips; ensure soil is thoroughly saturated each time you water your plants, top water & always use filtered water when possible.
Cutting off crispy edges can improve your plants aesthetics, and it wont hurt the plant.