Pruning = Harvest
The best way for a home gardener to get the best out of their leafy greens is the ‘cut and come again’ method.
This method is practiced by cutting a few of the outer leaves of each plant while leaving around 2/3 of the plant. This allows the plant to force new leaves to grow and not resort to flowering very soon. If you leave your plant for a long time without pruning (cutting) it will slow its growth down and begin to flower.
In a large enough garden, you can gather all of the pruning which will give you back more leaves in a matter of days, and turn it into a harvest. This is how I always harvest my leafy greens to get them to live longer and produce faster.
Just cut a few of the outer leaves, leaving the plant still strong enough to create more leaves. Never strip away your plant.