I grow okra in zone 4. Definitely start the okra indoors. I'd say about the last week of April. Give the seed plenty of heat to germinate. I had to develop my own variety, because okra accustomed to warm climates is not at all happy in my cold garden. The first year I grew okra it only got ankle high. The second year it got knee high. This year it was waist high to taller than the farmer.
Trialing a new variety that failed.
I've noticed huge differences in how different seedlings and cultivars grow. So I plant lots of seeds and cull the slow growing ones. If they grow slow in the greenhouse, then they will continue to grow slowly when transplanted outside.
Cull slow growing plants.
After three years of selecting for better growth in my garden some of the plants are as tall as the farmer.
Enough left over to share at the farmer's market.
