It helps your plants produce the goods!

Plants need phosphorus to produce fruits, flowers, and seeds. It also helps make your plants more resistant to disease. Phosphorus doesn't dissolve like nitrogen. The soil will hang onto phosphorus, not releasing it into water. What this also means is that plants get their phosphorus from moving their roots through the soil, rather than drinking it in with water (those crafty devils).

To make sure your plants get the proper amount of phosphorus, don't just pour the fertilizer into the pot. Mix it deep into the soil so the roots can reach it. Fertilizer sticks that can be placed near the roots or below newly planted seeds will also work.

If you're looking for good sources of phosphorus, check the ingredients of any plant food you buy. The "P" number of the "N-P-K" formula will tell you the percentage of phosphorus, by weight, in the mix. You should also look for ingredients like bonemeal, colloidal phosphate, or rock phosphate.

You may also see superphosphates, a more soluble form of phosphorus. Be careful with these: Overfeeding with superphosphates can actually create phosphorus deficiencies because they wash away too easily (the perils of a "quick fix").