Mysterious Phalaenopsis Leaf Deformation: Experimental Approach

Phalaenopsis Growing Tiny Thick Leaves: Unknown Cause

Karen (20+ years experience, 12x12 ft greenhouse, San Fernando Valley, CA). Temps 60-110°F summer, 60-80°F winter. Light 100-2000 FC. Keeps Phalaenopsis in sphagnum moss for moisture/humidity. Fertilizes lightly every other week (commercial, no urea), plus "super food" supplement (B vitamins, trace nutrients). All Phalaenopsis growing very small, thick, stumpy leaves (2-3" vs former 15"), almost round not elongated. Phenomenon in all Phals, not Dendrobiums/Cattleyas. Flowered normally this spring, still growing weird leaves. Repotted a couple—roots gorgeous. Stumped.

Expert Response

Karen, also stumped. Perfect situation for experimentation. 1) Move half dozen plants to standard fir-bark mix, grow alongside sphagnum ones, same feed/water. Tests if sphagnum is cause. 2) Two more test groups: one in sphagnum, one in bark, but alternate 3 different fertilizers (rotating to avoid micronutrient concentration from single fertilizer). Chicago grower with 6 decades experience uses this. 3) Heat stress: move several plants to area not exceeding 85°F, see if improvement. Share findings if you test.