Updated: Nov 21, 2019
In addition to the type of plants you are growing, there is a whole range of factors that dramatically impact the frequency at which you will have to water your plants. Variation of these factors is why you should never water your plants on a schedule.
Size Of Plant
Larger plants need more water than smaller ones. With more vegetation, larger plants absorb more through their roots, use more for respiration and lose more through transpiration. Having said that, younger plants, which are growing vigorously can sometimes have higher water requirements than larger plants that are not actively growing.
Higher indoor temperatures will increase evaporation of water in your plants, meaning they will dry out faster. There will be variation in the temperature of your house from summer to winter and from one room to the next. Rooms that get a lot of sun during the day can be considerably warmer, greatly affecting the watering requirements of your plants.
The humidity present in the atmosphere will have a big impact on the rate of evaporation of water from the soil and the rate of transpiration from the leaves. Our homes tend to have lower humidity levels in the winter when windows are shut and the heating is on. Bear this in mind when thinking whether your plant needs to be watered or not.
Type Of Pot
Porous materials such as terracotta lose water much faster than plastic pots, which prevent any water from getting through to the sides of the pot. Try to choose a pot type based on the type of plants you are growing. Plants that prefer arid conditions and well-draining potting mix will do better in clay pots.
Size Of Pot
Do not put plants like succulents and cacti in a large pot with too much potting mix. Even though the potting mix is well-draining, the quantity of soil in the large planter will take forever to dry out and the plant will wither away. Pick a pot size suited to the plant. Choose smaller pots for plants that like potting medium to dry out rapidly. Choose larger pots for plants that like evenly moist conditions.
Type Of Potting Mix
Potting soil with higher amounts of organic material or small, tightly packed particles will hold onto water more readily. Adding sand, perlite or vermicompost will improve drainage. You can often get premade potting soil tailored to your plant, but it’s easier and cheaper to make your own and you can tailor it exactly to the needs of your plants.
Moving air will increase evaporation and therefore increase the water requirements of your plants. Moderate ventilation is a great thing for plants, as it can reduce the risk of disease, but it will increase water requirements.
The time of year will play a significant role in how often you should water your houseplants. Many houseplants grow much more slowly or are dormant in winter, which will dramatically reduce their water requirements. In addition, less sun, ventilation and cooler temperatures in winter can make a massive difference to water requirements. Your watering habits will need to adjust if you want to keep your plants thriving.