Plant Parent Basics: Food and Fertilizer
As part of our feature series, Plant Parent Basics, in this article you will learn about the essential plant parent task of feeding and fertilizing your plants.
Why do my house plants need food?
All indoor plants nee an adequate supply of nitrogen (N), phosphates (P2O5) and potash (K2O) together with small amounts of trace elements (Mn, Mg, Fe, Mo, S, B, Zn, Cu). House plants especially need food because their soil in the pot has a limited amount of food, which is continually depleted by the roots and leaking out through drainage holes.
For all house plants, when the plant is in its active growing season, it must be fed. Most cacti can survive for a long time without feeding, but foliage plants and flowering plants coming into bloom can be seriously affected if not fed during their growing season.
White crust on the outside surface of a clay pot is a sure sign of overfeeding.
What kind of food do plants need?
As mentioned, house plants need three essential “foods” to help them grow well. These include:
Nitrogen
Plants use nitrogen to make leaves. Also known as N.
Phosphate
Plants use phosphate to make roots. Also known as P2O5.
Potash
Plants use potash to make flowers. Also known as K2O.
Other trace elements that plants need in small amounts include: Magnesium (Mg), Iron (Fe), Sulfur (S), Zinc (Zn), manganese (Mn), molybdenum (Mo), boron (B), copper (Cu).
The majority of house plant food should include a 1 -1 -1 ratio of the three essential foods. Some foods have more nitrogen or phosphate, and generally speaking that is fine. However, if a plant food you are considering to buy does not have all three essential foods, do not buy it.
Cactus food is slightly different than regular houseplant food because it is higher in phosphate than nitrogen. We recommend a 5 -10 - 5 ratio (or wherever the phosphate is double the amount of nitrogen).
What’s the best way to feed my plants?
There are several different types of food to give your houseplants. What’s “best” really depends on the plant’s needs.
Insoluble powder or granules
This type of food is widely used in gardens, but not so much indoors. This type of plant food is deposited on the surface of the soil, but is not readily taken down to the roots, where it is required. This method is not ideal for cacti or succulents because you cannot cut off the supply of food when the plant enters its dormancy period.
Liquid
Most plant folks would agree this is the most effective way to feed plants in pots. Watering and feeding are thus carried out at the same time, which saves you time and helps you avoid overfeeding. All you need to do is follow the instructions on the bottle.
Pills and sticks
Pills and sticks definitely save you time, as you just push them into the soil in a house plant pot. However, since the nutrients are concentrated in one spot, it does not promote even root development. Moreover, like insoluble powder or granules, the nutrient supply is near impossible to cut off when dormancy begins.
When do I feed my plants?
House plants should only be fed during their active growing season, spring and summer. However, for some cacti, such as the Christmas cactus, the active growing season is winter, and so they should be fed during colder months.
For flowering plants, food rich in potash during the active growing season is important.
How do I know if I am giving the right amount of fertilizer to my plants?
You’ll know if your plant is getting underfed during the growing season if you see:
Slow growth, not resistance to pets or diseases.
Flowers are absent or small and poorly colored.
Stems weak, early dropping of lower leaves.
Leaves that are pale, or “washed out”; yellow spotting might also be present.
You’ll know if your plant is getting overfed during the growing season if you see:
Leaves wilting
White crust on surface of clay pots
Growth is stunted in summer
Crisp brown spots; scorched edges
If you’re unsure how to feed your plant, please reach out to us via email or a direct message via Instagram. Pictures are encouraged.