I was given turnsole seeds in 2019 and didn’t get a chance to plant them until this year. I was not sure that any would grow. I tried a few things before putting the seeds in the ground. One third of the seeds were soaked in water before planting, one third were soaked and the seed coats nicked, and the last third were left alone and planted without nicking or soaking. Half of each group was planted in a pot and the other half were planted in a flower bed in the same area. I watered the seeds after planting them and watered them each day for several weeks.
While the other seeds I planted around the same time sprouted (morning glory, zinnia, sunflower, cosmos), the turnsole did not, so I stopped watering them. That’s when I was greeted with a surprise. After several weeks of not watering the seeds, I found two sprouts! The plants kept growing and flower buds began to form. Soon little yellow flowers bloomed and the telltale tri-lobed seed pods began to form.
Baby turnsole plants 
Growing turnsole plants 
Flower buds
I am still waiting for the pods to ripen and collect both the seeds and the pods. The seeds I will plant in the spring, although I may leave a few in the pot to see how they do with some cold during the winter. The seedpods I will soak to extract the red color. Hopefully I will have more plants next summer and will be able to pick some pods before they fully ripen to extract a blue or purple color.
As the seed pods form, they begin to droop. 
Swelling seed pod
Recipe from De Arte Illuminandi (Pages 5-6) to make clothlets with turnsole:
It is made also in another way from the plant called turnsole, and it stays blue in color for a year; afterwards it turns into a violet color. Now this is the way to make the color from this plant. Take the seeds of this plant, which are gathered from the middle of July up to the middle of September. And it has yellow <…> and its fruits, that is, those seeds, are triangular. That is because there are three seeds joined in one. And they should be gathered when the weather is fair. And the seeds are to be freed from the stems from which they hang, and put into an old, clean, linen or hempen cloth. And fold up the cloth, and draw it through your hands, until the cloth is saturated with the juice; and the kernels of the seeds do not get broken. And have a glazed porringer and squeeze the juice out of this cloth into this porringer; and again take some more fresh seeds of the plant and extract the juice in the same way, until you have enough of it. Then take some other good clean linen cloths which have been wet down first once or twice in a lye made with water and quicklime; and then wash them very thoroughly with clear water and dry them. (They can even be prepared plain, without <using> the lime.) And when they are dry, put them into this porringer where the juice of the aforesaid plant is; and let the cloths soak up enough of this juice to saturate them thoroughly. And let them stand in this porringer for one day or a night. Then have a dark, moist place, where you may put some garden loam in a winecup or other suitable dish, or upon screens, where neither wind, sun, rain nor water may get at it; and let there be voided upon this loam a quantity of the urine of a healthy man who has been drinking wine. And over it, furthermore, you upt up a structure of light reeds or other little wooden rods, so that the cloths soaked in this liquid may be spread out above the vapor of the urine, <but> in such a way as not to touch the wine-soaked earth described above, because they would be spoiled. And then let them stay this way for three or four days, or until they dry there. Then put these cloths under books and keep them in a box; or put them into a glass jar, close it up, put it in quicklime, not slaked, in a quiet, dry spot, and keep it.
The Research and Art of Marion Forester 