You would only need to add phosphorus in any form if your soil was deficient. And since most soils are rarely ever deficient, it is likely unnecessary.

btw, excessive applications of P, whether by fertilizers, soil amendments or the heavy use of manures, is one of the leading causes of groundwater pollution. In some places, it can be so bad that heavily P dosed amendments or fertilizers are no longer allowed.

The bottom line is don't add anything unless a professional soil test tells you it is necessary.

Thanks to you both! I have been meaning to get my soil tested, but haven’t found where to do it. Probably UWM ag department. Local nurseries I don’t think do it. I will find out.

debra

Look here...

https://city.milwaukee.gov/Health/Services-and-Programs/healthlab/testing-Fees/Soil-Screening-Information

tj

Do your hosta grow well? Yes? Then don't add anything.

If your hosta grow poorly, start by top dressing with good compost. When I plant a new hosta, I dig out the hole, set that dirt aside, and refill the hole with compost. This gives the new hosta excellent nutrition, and they grow faster than hosta planted in regular soil.

Keep in mind that adding a single nutrient to soil can give unexpected results, not always good results. Soil is an extremely complex substance. Also keep in mind that sales staff in garden centers will always recommend that you use soil supplements.

You could also experiment by dividing a mature hosta into 2 equal parts, or take 2 small divisions from the hosta, plant these side by side, but use rock phospate on only one and see what happens.

If I remember Correctly, phosphorus is the middle number in the fertilizer description (example 12-12-12). The middle number is generally the one that promotes flowering, which would be helpful in a vegetable garden, but not so much with a hosta.

bkay

Special thanks to you Tj today for the link. I have looked and will do it, just to know! As so as I get the time. Dhaven, that’s not a bad idea. But it has to be on a hosta that I can spare, not one of my new or treasured ones. Maybe a Fortuni Aureomarginata. I have two huge ones in the on the side of the house that no one ever sees. Maybe I can do the “test” with two pieces from that........probably creating more work for myself...... lol

debra