What is it?
Phosphorus is for fruiting and flowering. That’s how I remember it. Plants that you harvest for their fruit such as tomatoes, zucchini, and melons all need an extra dose of Phosphorus. All plants need Phosphorus, but these plants can use an extra dose.
Signs of Deficiency
If a plant does not get sufficient Phosphorus its leaves will turn red to purple in color. This deficiency will affect your yield.
There are many excellent organic sources of Phosphorus. Bone meal is probably the cheapest and has a Phosphorus content of around 12. This is fast acting and lasts up to 6 months. Another source is Rock Phosphate which has a 33% ratio. With Rock Phosphate you will only get about 10 the first year because it is slow acting and last 3-5 years.
Other fertilizers that have Phosphorus in more modest quantities include:
- Worm Castings,
- Alfalfa Meal,
If you notice a deficiency I like to use an organic hydroponic bloom solution like Earth Juice immediately. This has a P of 2 and is immediately available. Then I would work a little bone meal in around the roots and water weekly with the hydroponic solution.