Rinse the greens and pick out big stems, blades of grass, and any leaves that have started to turn brown.
Put the greens in the food processor and pulse 5 to 6 times, until they are tamed a bit.
Add the garlic scapes, pistachios, and lemon juice and run the processor motor until the nuts begin to disappear into the greenness.
With the motor running, stream in 1/4 cup olive oil. Stop motor and scrape down the walls of the bowl and run some more. If the pesto looks very dry, add remaining oil.
Add salt and pepper and pulse to combine.
Taste and add more salt, pepper or lemon juice, should you deem it necessary.
To freeze this pesto, pack it into small jars. I like wide mouth half pints, but the tiny quarter pint jars also work nicely.
Fill the jars, leaving about 1/2 inch of headspace. Top the pesto with a very fine layer of olive oil. This will prevent the pesto from discoloring or developing surface freezer burn.