The tigridia have finished flowering, having had at least 4 or 5 blooms per stem. The seed heads have started to form and I would like to know if they should be left or if they should be removed. Also, will the plants die back? Should the container with these in be placed in the greenhouse in the winter?
Yes, you can remove the seed heads to improve the appearance of the plant. If you enjoy how they look, you can leave them in place as well.
If you live in gardening Zone 7 or 8, you can mulch the plants heavily to keep them safe in the winter. If you are in Zone 6 or colder, you should bring the container indoors or into a warmer greenhouse.
I have these in a large planter under a taram with slate on top, so removing them for winter is not possible the stems are now dying. Do I need to cut back or just let them die, is it possible they will regrow next season? Many thanks, Brian (garden novice)
You can lift the bulbs and store for winter.
Here is a link with more information.
How long would I wait for a flowering plant to appear when planting from the seed. Year or years?
A Tigridia plant should flower in its first year, just a few months after planting the seed. They flower in late spring or early summer, usually around June.