Coffee, Tea, or Vitamins? Proper Houseplant Nutrition

Most plants need, in addition to sunlight and water, “food” from the soil to thrive. Go through a garden store, or the gardening department of a discount store, and the options for feeding our little green buddies can be daunting. Do we buy granules, spikes, or liquid? Is it necessary to buy specialized plant foods for, say, African Violets, orchids, cacti, or will a general-purpose blend do the trick?

And is it really necessary to purchase this stuff at all?

Serious outdoor gardeners scoff at those who purchase chemical fertilizers, calling them a crutch for the lazy. Purists use compost, and that’s that. This holds true for indoor gardeners as well, to a point. Indoor gardeners lack a few of the outdoor benefits; we have no earthworms, very little of the natural, friendly bacteria present in outdoor garden soil, and a rather controlled climate as opposed to the extremes that help nature’s cycle on its course.

We can still benefit from their methods, though. And I propose that good gardens, both indoor and out, depend on both methods of feeding. Even the most dedicated organic outdoor gardener will admit – or should admit, anyway – that there’ve been times when he’s at least been tempted to break out a package of “Miracle Gro.”

Compost is really nothing more than a fancy word for rotted plant material. It’s easy to make, too, even if you’re limited in space. As a gardener in a suburban yard, I have a big compost pile out back by the shed. I dump in yard waste, grass clippings, autumn leaves, shrub trimmings, and vegetable peels from the kitchen. We also toss in ashes from the bonfire and try to remember to stir it up occasionally. But if you don’t have the room or inclination for this, just dig a hole. Make it about as big as a five-gallon pickle bucket, fill it up with kitchen or yard waste, cover it over with soil, and mark its spot. This time next year, you’ll have some serious, free, plant food.

No yard to dig in? Use what you have at have at hand. Most houseplants like coffee grounds mixed in with their soil. If a friend with an outdoor garden buys a bag of aged manure, ask to take a handful in a baggie. When you get home, dump it in a bucket, add water, and soak it overnight. You’ll have a perfect – though not totally odorless – plant food. (The odor won’t last.)

There comes a time, though, when chemical, store-bought fertilizers are necessary. They’re easier, too, especially on a small scale.

My personal preference is to purchase potting soil with time-release fertilizer granules mixed in, then when the recommended three to six months is up, to use liquid plant food. For general purposes, don’t bother with expensive “houseplant” fertilizer in the tiny bottles – buy ordinary liquid plant food and dilute it according to package directions.

How much to feed?

It’s better, actually, to err on the stingy side. Most houseplants can happily live for a year or more with no fertilizer at all, even in soil that isn’t enriched with granules. Overfeeding can burn the plant, and feeding with the wrong combination can interfere with the growth cycle – more on that later. Feed most generously in late spring/early summer, and gradually cut back from there until mid winter, when you’re not feeding at all.

The numbers on the fertilizer box or bottle – reading something like this: 10-10-10 – stand for NPK, or Nitrogen, Phosphorus, and Potassium. They are higher in Nitrogen when leaf development is desired, as in the case of foliage houseplants. They are higher in Phosphorus when root, flower or fruit development is desired, as in the case of new transplants and flowering plants. Potassium simply helps the plants withstand stressful conditions, like when you forget to water on time. So purchasing plant food formulated for your particular plant is useful, but generally not crucial.