I live at 45 degrees north in Wisconsin and the garden index says last week in may for planting at a 90% of no frost. Unless the water you are near is from a flooded rock quarry or the Fox river (Lake Winnebago downstream), it should be ok. Most of the rivers and lakes have farm run-off, making them already loaded with nutes. Get some of that brown Chippewa river water and watch them go! Watch out for the farmers, they know everything about weed and gorilla ops. Good luck.

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"There's no money for your issues so long as we're squandering $50 Billion a year on the drug war"- Ben Masel