Hi  I have two 6ft Dicksonia Antartica in my garden approx 4ft apart in 500x500x500mm stainless steel pots. One is and has been producing healthy sized fronds whilst the other has been growing very small fronds and has been doing so for 3 years now......any ideas on how I can assist the weaker tree fern produce a healthier frond? Both are located in semi shaded areas in the garden Kerry