Flowering Has Nothing To Do With Fertilizer

When I worked in garden centres, one of the most frequent questions I got was, "What fertilizer can I use to get my plants to flower?"

Answer: "None."

Modern marketing has sold us the idea that a 'flowering fertilizer' will make your plants flower, and we've bought it. But that's about as logical as saying, "Eat this multivitamin and you'll have a baby." Fertilizers are food, and food doesn't instigate sexual reproduction in the plant or animal world.

Let's go inside the 'mind' (or logic rather) of a plant for a minute. The purpose of life is to reproduce, and everything you do is geared towards that moment. You grow, vegetatively, for a while, maybe an entire season, maybe for fifty years, and reach sexual maturity eventually. You're now strong enough to put your energy into creating new life. Of course, you want everything to be just right in your environment so your offspring have the best chance for survival, and you want to ensure that you are at your peak of physical strength.

So, how does a plant make sure all these safeguards are in place? You wait for the right season, when water isn't too much or too little, you wait for nutrients to be at their most available, you want to be strong enough to thwart pests, and you want to choose a time when pests are at their weakest. So much of this depends on a season, and so many of these variables are not dependable, even seasonally. So, how do plants know when to . . . get it on?

Light. It's what horticulturalists and botanists refer to as a photoperiod. Photoperiods are essentially the length of day, versus the length of night. Some plants need a certain amount of light to flower, others need a certain amount of darkness to flower. Poinsettias are a plant that is notorious for its photoperiod, requiring less than 12 hours of light to initiate flowering. Some people just throw them in a closet for a few days in total darkness to prompt flowering. They need the dark, not the light, to flower.

There are short-day plants, and long-day plants. Short-day plants, as suggested, require a short day and a long night in order to flower, and long-day plants, the opposite. Not all plants have a photoperiod, and some are considered 'insensitive', but some can still be influenced to some degree with different durations of light.

A flowering fertilizer has a larger quantity of phosphorous, the middle number (30) in a 10-30-10 for example. Phosphorous is used by plants in larger quantities to produce flowering and reproductive tissues (as well as by the roots). So, providing a flowering fertilizer (or a transplant fertilizer, as they both have high phosphorous content, just a different label) will help your plants produce more flowers, and bigger flowers, but only if there are deficiencies of phosphorous within your soil to begin with. In no way, whatsoever, will fertilizer make your plants start popping out flowers.

Your plants are waiting for the right photoperiod, and if you give it that, flowers will surely follow. But, just as in humans and other animals, they only want to do it when the time is right, when environmental stress is at its least, and the plant can execute the plan with the least risk of failure. Stress kills the mood for us, and it does for plants too! Even with that being said, some plants are just stubborn and don't feel like it. They do, eventually, come around, but it can take a year or two to cycle through the seasons and get back to the right time, when the plant wants to.

Most of my plants flower around Christmas time. My African Violets flower from about December to February, my Aloe has flowered each winter, along with most other cacti, and many others just pump out the blossoms when the days get short, about 10 or 11 hours short. My plants are exposed to a full day of sun in the south-facing sunroom, so their exposure is very natural. In the home or office, with artificial lighting, blinds, curtains, walls and other obstructions, many plants get little, erratic or no changing photoperiod, making flowering unlikely or random.

Knowing where your plants originate can answer questions about their natural photoperiod, and then there's always google. Just get the watering optimized, feed regularly (which isn't even necessary, but will help your plant stay strong and produce more), and apply the desired photoperiod. Boom. Flowers!