Asparagus plants (Asparagus officinalis) are uncommon because they are dioecious, which means some plants are male while others are female. You may have heard that male plants are better producers of asparagus spears and, because of this, could be thinking about replacing your female plants with males. Even though this isn’t necessary if your plants are healthy and producing a harvest, there are several reasons why male plants are usually preferable to female plants.
A Larger Yield
Although both female and male asparagus plants can creates flowers, only the female plant produces fruit, which can be little red berries that you’ll see clinging to asparagus ferns on the summer. Because male plants do not use saved nutrients to make fruit, they typically have more energy available to make new spears than female plants. This means that you’ll harvest up to three times as many asparagus spears from male plants compared to females, an advantage that becomes especially apparent after the second or third year the plants are in your garden. Male asparagus plants also tend to begin producing spears earlier in spring than female plants, another advantage of the all-male plot.
Asparagus plants are perennials that typically live about 20 years, but male plants tend to live more that female plants, probably because they expend less energy and use less saved nutrients during their life span. Because the delicate asparagus ferns on female plants carry fruit, then they are heavier than ferns on plants. In strong winds or heavy rain, ferns on female plants tend to bend into the ground and lodge in moist soil. That is unsightly and can compromise the health of the plant when fungal organisms grow on moist ferns. Additionally, because male plants do not produce fruits, an all-male plot won’t be filled with “volunteer” seedlings from dropped fruits. These seedlings are normally inferior to carefully bred cultivars and compete with adult plants for nutrients.
Removing Female Plants
If you choose to replace your female asparagus plants with male plants, it’s ideal to do some planning the season prior to making the change. Harvest spears as usual, stopping when spears become thinner than a pencil’s diameter, and allow all of the spears to grow and develop into ferns. As summer progresses, await the appearance of red fruits on some ferns, signaling a female plant, and place a wooden or plastic marker well to the soil at that plant’s base. Do not use ties on stems as markers, because these can be discarded in windstorms or if the plant dies back in winter. Early the next spring, dig up the marked female crowns, taking care to remove all the roots but preventing disturbing roots of different plants, and replace the females with plants.
Selecting Male Cultivars
When selecting new male plants, begin with 1-year-old, healthy, dormant plants, called shingles, accessible from reputable growers. Asparagus cultivars that produce only male plants were initially developed by Rutgers University in New Jersey, so “Jersey” is generally a part of this variety’s name. These magnets also tend to be more tolerant of warmer areas compared to older varieties, which generally rise in U.S. Department of Agriculture plant hardiness zones 4 through 8. For instance, the cultivar “Jersey Giant” grows in USDA zones 3 through 10, while “Jersey Supreme” grows in USDA zones 2 through 9. The cultivar “Jersey Knight” is a vigorous cultivar that’s a fantastic selection for humid places, because it’s resistant to fungal diseases. In addition, it does well in heavy, clay soils and grows in USDA zones 4 through 9.