I have several Japanese painteds that were so lush last year - some were over a foot and high even wider. I don't protect them over winter (I live near Chicago and it gets down to 20 below or even more). Is that why they come back so tiny? I was told they were winter hardy and good in Zone 5. Some are a little bigger than others but nothing is more than 4 or 5 inches high. Most are an inch. I never fertilize and they are in fairly good soil to which I add mushroom compost every other year. Is it just too early in the year? Would it help them to use a liquid like Algoflash? I'm new to ferns so any ideas would be much appreciated.

Westy