Checking indigo leaves for color…not yet. No sign of blue yet when leaves are crushed, just chlorophyl green. Anyone have any other suggestions for checking for indigo other than the “crush and look for blue” method for either of these species?
Persicaria tinctoria on the left, indigo suffruticosa on right.
Japanese Indigo starting to push past 12″ high. 
And the indigo suffruticosa is two heights, the one that overwintered is over 4′, in the foreground you can see this year’s seedlings at about 12″. Curious to see if older plant still yields indigo. And I do provide plant supports, because the wind sometimes really blows here in the Texas Hill country and if a major stalk breaks my gardener’s heart will suffer in sympathy. 
debmcclintock 
Wow! Your suffruticosa looks great! I don’t think the age of the plant makes any difference in the amount of blue it yields. The plants on Ossabaw Island are old and the give a strong blue. It’s not like woad. Usually when the plant blooms is the time to use it, that’s when the indican is the strongest in the leaves. In the last picture the plant on the right looks like it’s almost ready, does it have any blooms, yet?
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Thanks! Good to know the older vintage still gives blue. I’ll have to work harder on winter mulching. I lost 50% last year. But I did nothing to protect the roots. No blooms yet, I’m watching. This May we had ALOT of rain and minimal sun so I am thinking the plants are running slow on the indigo development timeline. Thanks for feedback.
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Hi Deb! you are so lucky! I would just love to have leaves to print with – I think they print turquoise!
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Margo, you do get a dark blue with printing but with a fresh leaf blender…ahhh green to turquoise! Here’s another blog that gives great fresh Japanese Indigo leaf adventures. http://johnmarshall.to/blog/2015/01/23/fresh-leaf-indigo-its-magic/
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try freezing it and see if the blue shows!
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Arlee, great idea, to the freezer tomorrow!
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