So you planted it on may 24th? So 6 weeks and it's this small and flowering? My guess is that cannabis loves light, especially sunlight. Now in order for these things to get big and veg into big monsters it needs more than 12 hours of constant light. That's why people indoors usually have a light schedule of 18 hours of light and 6 off. (And use powerful lights,, but not as powerful as the sun) Once they get big enough to desired size they change the light cycle to 12 hours of light and 12 off. This causes the flowering effect to take place. When outdoors you rely on the earth to change its tilt (change of seasons)for example spring to fall is the peak season to grow most annual plants. This is cause there's more light in the spring to grow the plants big for a summer and fall is when you harvest your fruit because there's less light. So my guess is your plant wasn't getting enough light it's entire life so it said fuck it and started to flower so it can die. Basically committing suicide because it's life is terrible. I mean not enough light.