Basics of Inorganic Fertilizers

This year I had an indoor Christmas cactus that never did bloom. Turns out, I didn't fertilize it appropriately. I'm now hoping for a "Valentine's Cactus". I've also had some very stagnant indoor African Violets and Orchids, as of late. I've never been very consistent about fertilizing in the Spring, but this year, I really want to give my plants the best start that I can.

I'm also terrible at remembering what to use where, so I'm writing this down for posterity and so that I (and you) can reference it later. In full disclosure, I do prefer to use organic fertilizers like black cow and composting soil (from a tumbler or worms), but since that isn't always available here are some basis of inorganic fertilizers.

Inorganic fertilizer is basically composed of three main "ingredients": nitrogen (N), phosphorus (P), and potassium (K). These chemicals are used in various ratios to drive differing results in plant growth: nitrogent for shoot growth, phosphorus for root growth and potassium for fruits and flowers. I once heard that if you can't remember how component each is used to remember: shoots, roots, fruits. This stuck with me! A fertilizer that is labeled 10 - 10- 10 is equal parts nitrogen, phosphorus and potassium. So, if you are trying to encourage root growth, you'd choose a fertilizer with higher 2nd number: indicating that there is a higher ratio of phosphorus in the product as compared to nitrogen and potassium. Similarly, if its blooms you are after you'd choose a product with a higher "3rd" number, for potassium.

Here are some examples, using products you may have heard of:

• Holly Tone is a 4 - 3 - 4 fertilizer. That means 4% nitrogen, 3% phosphorus, 4% potassium. The label recommends it for evergreens, cameillas and hollies. You could use a fertilizer higher in potatssium (the "fruits") to drive more blooms on blooming evergreens like Cameillas.
• All Purpose Miracle Grow - is a 12 - 4 - 8 fertilizer. Its most commonly recommended and used for annuals and you and see why as it promotes lots of green "shoot" growth and blooms.
• Osmocote Plus - is a 15-9-12 fertilizer.
• Superphosphate fertlizers contain a ratio of 0 - 46 - 0 and they are often used during Fall plantings to encourage root growth while getting plants established.

Hope this helps. While there is lots of science behind fertilizers, selecting and applying one isn't scientific. Problems like root burn and other negative side effects can occur. My advice is to not over do it and consult help from a master gardener or garden center expert when you need it!