Snap spears off at ground level while the growing tip is still tight. When the average diameter of the spears is less than one-quarter inch, stop harvesting and allow ferns to form. Older varieties of asparagus like 'Mary Washington' produce both male and female plants. Female plants generate seed, which makes them less productive. Male plants out-produce female plants, because all energy is devoted to spear production.
Heavier yields occur in warmer regions.
Many of these varieties also have greater tolerance or resistance to diseases like Fusarium wilt and rust.