I have a rooftop garden with lots of sunlight and was given some 20-20-20 by a family member. I fed it to my tomatoes last summer on a monthly basis and am eager to have my garden this year grow up strong. Among the plants we are growing are figs, blueberries, hot peppers, mint, raspberries, tomatoes, and various ornamentals (e.g.: jasmine). I gather the 20-20-20 fertilizer is potassium, phosphorus, and nitrogen. Will this harm the environment when it eventually leaches out into the gutters? Are there any proven dangers for consumption of foods raised with this fertilizer? Finally, is it necessary and/or beneficial? Thanks!
Overkill in most situations. Sold for use on hanging baskets and in other circumstances where it is assumed high numbers needed to compensate for heavy leaching of frequently watered soil-less potting media. If you are growing in actual soil in the ground you should see about sampling your soil and having it analyzed before doing much additional using of high potency fertilizers like this. The second 20 in particular could become quite problematic if over-applied, as phosphorus leaches very slowly.
Thanks for the reply, Ron, greatly appreciated. Our plants are all in pots and they do get flushed relatively often. Do you know if it's still a good idea to fertilize? Also, how often is good for the plants? Are there any environmental/health concerns we should be aware of?
