Tropical Milkweed under grow light issues.
Hello fellow gardeners. This is my first year growing plants under grow lights. So I decided to grow some Asclepias Curassavica (commonly called Tropical Milkweed) for the Monarch butterflies (their host plant). The plants look great and are growing faster then expected. But most of the plants are starting to form little red spots or red edges around most of the leaves especially the bottom leaves. Eventually the leaves will turn a pretty yellowish red and fall off. What could this be? The plants seem fairly healthy except for this.
Here's some back ground information on them.
-They're under fluorescent grow lights ( the Jump start T5 brand)
-They're about 5 inches from the light
- They take about 16 hours of light a day.
-They're considered full to partial sun plants
-They like moist soil.
I think the problem might be the light. But would love suggestions. Thanks Ed.