As part of our feature series, Plant Parent Basics, in this article you will learn how to distinguish between the different levels of water different plants need, and how to provide it for them.
Why is it watering important for plants?
Without water, a plant will die. Water is essential to the process by which plants make food from sunlight, photosynthesis, and other processes, such as transpiration. Water is taken up by the plant’s roots and provides hydration for the trunk, leaves and stems. How water actually performs the gravity-defying feat of moving up a plant is still largely unknown to scientists.
How should I be watering my plants?
There are two standard methods you can use to water your plants. One is via a watering can and the other is known as the immersion method. Both methods are concerned with watering the plants’ soil, not their leaves or stems, as the roots are the primary vehicle that plants use to absorb and distribute water.
Ideally, you will want to use a watering can with a long, thin spout. Insert the spout under the plant’s leaves and pour the water steadily and gently. Take great care when watering plants in pots that do not have drainage holes. If there is still any free-standing water on the top of the soil 30 minutes after watering, pour it off.
The immersion method of watering is reserved for plants who do not like to have water on their leaves, such as African violets. Immerse their pot in a larger container filled with water to just below the soil layer. Let them soak for 10-30 minutes. Then let them drain and dry before returning them to their home in your home.
You can also use the immersion method to water plants that you notice are not absorbing the water you give them or with plants whose water runs straight through their pot. These problems are caused surface soil caking and soil shrinkage away from the side of the pot but can be easily remedied by watering via immersion.
What plants need more water than others? What plants need less water than others?
Each and every plant has its own basic need for water. The frequency and amount of water depends on several factors, which can make watering tricky. These factors include:
the species of plant,
the size of the plant,
the size of the pot,
the drainage and material of the pot,
and most importantly, the time of year.
We’ll cover the the latter factors in the next section. For now, here’s a spectrum of the three basic water needs of the various species of house plants:
DRY IN WINTER
Cacti and succulents should be treated as moist/dry plants during their active growing season (spring/summer). During the winter, the soil must be allowed to dry out completely.
Plants in this group: Desert cacti, succulents, hoya, palms, bird of paradise, ZZ plant, snake plant
Most house plants are in this grouping. We recommend watering these types of plants thoroughly and frequently during the active growing season (spring to autumn) and water only sparingly in winter. Let about 1/2 inch, or to the first knuckle on your index finger, of the surface soil dry out between waterings; this is especially important in winter when the plant is dormant or at rest, and not actively growing.
Plants in this group: Fiddle leaf fig, rubber tree, philodendrons, pothos
MOIST AT ALL TIMES
Most flowering house plants are in this category. The soil is to be kept moist, but not wet, at all times. Water these plants carefully each time when the surface of the soil becomes dry, but never enough to keep the soil permanently saturated with water.
Plants in this group: Ferns, calathea, alocasia species, including African mask
A NOTE ON AIR PLANTS
Since air plants do not include soil, they have different watering needs. For more information on watering air plants, see our article dedicated to the subject.
When should I be watering my plants?
The easiest way to find out if your plant needs water is to look at the surface soil according to the type of plant.
PLANTS IN ‘MOIST AT ALL TIMES’ CATEGORY
If the surface is dry and it is a plant in the MOIST AT ALL TIMES group, water the plant.
PLANTS IN ‘MOIST/DRY’ and ‘DRY IN WINTER’ CATEGORY
For plants in the other two categories, MOIST/DRY and DRY IN WINTER, insert your index finger into the soil up to your first knuckle and if the soil is dry, water the plant. The only exception here are the cacti and succulents who need to be kept dry in the cooler months - leave these guys alone.
How often should I be watering my plants?
As we’ve mentioned in other articles, a plant will tell you when it needs more water or is getting too much water. Generally, watering intervals depend on three factors:
1. PLANT SPECIES
Fleshy plants like cacti, succulents and some tropical species, can tolerate drier conditions than others. The general rule is the larger the leaf surface and faster the plant is growing, it will need frequent watering (most tropical species). The “fleshier” a plant, the less it will need frequent watering (most succulents and cacti).
2. TIME OF YEAR
In the winter, water significantly less often for all plant species. Until new growth begins in the spring, watering two to three times a month in winter is enough. During the growing season, increase watering to one to three times a week, depending on the plant type (DRY IN WINTER, MOIST/DRY, or MOIST AT ALL TIMES).
3. PLANT’S ENVIRONMENT
When the temperature and amount of daylight increases, so does the need for water. The size and type of pot is also an important factor to consider: smaller pots typically need more frequent watering than larger ones; clay pots typically need more frequent watering than plastic pots.
How do I tell if I am watering my plant too much?
Your plant will tell you if you are watering it too much, regardless of the plant species. Here are the warning signs of overwatering:
Leaves are limp, soft and may have rotten areas
Leaves fail to grow and mature, stunted growth
Leaves are curled, yellow and wilted; tips may also be brown, but not dry
Flowers are moldy
Both young and old leaves yellow and fall at the same time
Roots are brown and mushy
Plant soil emits a foul, rotting odor
How do I tell if I am watering my plant too little?
Your plant will also tell you if you aren’t watering enough , regardless of the type of plant. Here are the warning signs of under watering:
Leaves are limp and wilted
Leaves have little or no growth
Lower leaves curl, yellow and wilt
Leaf edges are brown and dry
Flowers fall or quickly fade
Oldest leaves fall first