With some fertilizer knowledge under our belts from the last two weeks (Up, Down, All-Around and Liquid or Solid), now we need to figure out when a plant is in need of some food.
The two most common signs that a plant needs fertilizer are slow growth and yellowing leaves. If a plant has been growing and thriving, but then just sort of stops, that is a pretty clear sign that it is time to give it some food. Remember, houseplants only get what you give them. They don't have the opportunity to grow root systems in search of nutrients or to collect minerals from natural material decomposing in the soil around them.
The other sign a plant will give you that it needs fertilizer is yellowing leaves. Sometimes, the yellowing will be in between the veins of the leaf, so you'll have green along the veins, but yellow in the areas in between. Other times, a plant will just have a yellowish look. Leaves that were once green and lush will look like they need a little pick-me-up. In both cases, when you see this in your plant and you haven't fed it in a while, it is time for fertilizer.
The way I fertilize my own plants is this: Every 90 days or so I put a small scoop of osmocote to give an even balanced feeding all of the time. In peak growing season, which in Florida is from March to September, I fertilizer with FoxFarm's GrowBig on a weekly basis. That keeps everything green lush and thriving.
And that's the end of our little crash-course on fertilizer. Remember houseplants need to be fed to stay happy and healthy, but it's easy to integrate into your plant-care routine.