Q.
I have some cacti in my backyard. Should
I fertilize them and when?
 |
| When cacti flower they need high phosphorus fertilizer. A rose or tomato fertilizer should work. |
A.
The standard answer is to fertilize them lightly in the spring of each year. That
is the standard answer. The purpose of fertilizer is to give the plants what
they need or what is lacking in the soil. Once plants have what they need,
stand back, and give them a chance to grow. Giving more fertilizer than they
need, and watering plants more often, does not necessarily make them grow
faster.
Fertilizers are not a magic “on and off” switch;
you can’t force plants to get larger and bigger by giving them more fertilizer
than what they need. All plants have a genetic “maximum” at which they can
grow. That is why most cacti grow slowly, and other plants may or may not,
depending on their “genetics”. For cacti, it depends on the fertilizer level,
watering and soil mix besides their “genetics”.
There is one fertilizer exception and it
is a bit tricky. Nitrogen fertilizers increase the speed at which any plant,
including cacti, get larger but you must be careful. There is a danger from
“growing too fast” for all plants including cacti. The fancy term is “luxury
consumption”. To maximize growth, apply nitrogen fertilizers no more than twice
during their growing season. Be judicious when watering them and don’t let the
soil stay wet. But if your cacti are growing well without it, then don’t use
it.