How to choose the best:
Kale

Touch

Look for crisp, robust leaves that are attached to a strong, tough stem down the center.

Avoid any leaves them seem to be soft or wilting at all, or have any soft or slimy spots.

See

Look for a deep green color across the leaves, and a lighter color through the stem, which can even dip to purple or red on some varieties.

Avoid any leaves that seem to be going yellow brown.

Some more details:

How to store

Kale does best in a humid environment, so try wrapping in a moist cloth or paper towel before storing in a plastic bag.

When it's in season

Jan. Feb. Mar. Apr. May Jun. Jul. Aug. Sep. Oct. Nov. Dec.

FYI: for this Vegetable, its best to buy organic.