The fastest way to get water off washed greens is to load them into a salad spinner and give it a few spins. The centrifugal motion flings water off the leaves and out through the holes in the basket's rim, clearing off a large amount of water in just seconds.
Without a salad spinner, greens can be wrapped in a clean kitchen towel or a few layers of paper towel and pressed gently. Blotting and pressing rather than wringing hard keeps the leaves from getting bruised while the towel soaks up the moisture.
Do the quick methods differ much?
Putting greens in a clean mesh bag or a thin cloth sack and giving it a quick shake works well too, whether outside or over a sink; the motion works much like a spinner, flinging off the extra water.
When using paper towel, spreading the leaves in a single layer dries them far faster than piling them up; leaves stacked in a heap keep the bottom layers damp for a long time.
Why does the greens need to be dried thoroughly?
Leftover water on greens keeps salad dressing from clinging to the leaves and waters the dressing down at the bottom of the bowl instead. That's why thoroughly drying greens meant for salad has a direct effect on both taste and appearance.
If the dried greens are going into the fridge, keeping them in a closed container lined with a paper towel lets the towel absorb any leftover moisture and helps the leaves stay fresh longer.
What happens if wet greens are stored anyway?
If greens with leftover water are left in the fridge, the extra moisture softens the leaf cell walls and speeds up rot; bacteria and mold also grow much faster in a damp environment than a dry one. That's why wet greens have a shorter shelf life than the same greens stored dry, by several days.
Greens that are washed but not thoroughly dried practically steam themselves inside a bag; water droplets that collect on the inside of the bag drip back onto the leaves and make the moisture problem worse. Using a container or bag with holes reduces this buildup somewhat.
Some greens are more sensitive to moisture than others; thin, delicate greens suffer from excess moisture much faster than thicker-leafed ones.
A kitchen towel used to dry greens doesn't need washing after every single use as long as it's dried thoroughly in the sun or open air between uses and reused a few times; what matters most is that it doesn't stay damp, since a damp towel creates a good environment for bacteria to grow.
The salad spinner itself should also be washed regularly; moisture trapped between the perforated basket and the outer bowl can start holding onto smells over time if it isn't cleaned.
Trimming off tough stems before drying greens also speeds up the process; stems hold onto more water than leaves, so keeping them separate makes both drying and later use easier.
Airing out the drying towel after every use also helps it absorb moisture more effectively the next time around.