Asparagus Plants: A Primer
Asparagus, or Asparagus officinalis, is a herbaceous perennial plant that produces flowers. Since people only eat the stalks of the plant, most don’t get to see it in all its glory, unless they grow asparagus at home.
Once the harvest period is over, the plant is allowed to grow frilly, fern-like leaves and flowers, until it is killed by frost for the year. The plant grows in many places around the world and is available in a range of varieties. You’ll find green and purple plants, and with a bit of tweaking, can also grow white plants too.
Asparagus Plants 101
As a perennial, asparagus continues to grow year after year. Many varieties can take some neglect and stress and will keep on growing, even if a gardener is less than attentive.
In the above video, a gardener rediscovers an asparagus plant he’d first planted in 1986. He expresses surprise that the plant is growing and at its ability to withstand drought.
There are two main types of perennials, according to the National Gardening Association. Woody perennials include trees and shrubs. These plants don’t die back to the soil level each year. Herbaceous perennials have soft, tender stems. Those stems can’t take freezing cold and do die back to the soil level every year.
Beneath the soil, the crown, or roots of the plant, are alive and well. But during the winter, it looks as though the entire plant is dead and gone. Once the soil thaws and the temperatures warm up in spring, the plant starts to grow again.
Where Asparagus Grows
Asparagus plants won’t grow everywhere. It’s commonly grown in North America, Europe and some parts of Asia. According to Modern Farmer, China produces the most asparagus, followed by Peru and Germany.
In the US, the biggest area for asparagus is found in Michigan. Oceana County has been dubbed the “Asparagus Capital of the World.” It’s home to the National Asparagus Festival, which takes place in June.
Even if you’re not in Michigan, China, Germany or Peru, you can probably grow asparagus plants. They do best in zones 8b or lower, according to Bonnie Plants. If you live in an area where it never freezes or where the winter is very mild, your climate is likely too warm for asparagus.
The plants need to go dormant during the winter, when the leaves and stalks die back. That period of dormancy gives their roots time to gain strength and store energy for the next season.
Of course, as a gardener, it’s important to never say never. Although the state of Florida is generally considered to be too warm for asparagus, some gardeners have reported success with the plant there.
It might feel weird to think of a plant as having a sex, but some do. There plants are known as dioecious, and asparagus is one of them. Some plants are female, some are male.
The big difference between female asparagus plants and male asparagus plants is the production of seeds. Both types will produce flowers, but only female plants make seeds. The seeds typically look like red berries.
You might notice a difference in spear quality between male and female plants. Female plants may make larger spears, according to the University of Minnesota. But male plants usually grow more spears than female plants in a season.
Although you might get an even mix of male and female asparagus plants when you grow them in your garden, some varieties are bred to only produce male plants. You not only get more stalks from male plants. You also don’t have to worry about seed production.
If a female asparagus plant drops seeds, those seeds can develop into plants. The problem is that the plants aren’t often true to the species. Many gardeners consider them weeds and will just pull them out of the soil.
When you’re looking for seeds or crowns to plant, you’re likely to come across a number of asparagus plant varieties. Cornell University lists 13 different varieties, for example.
The differences between varieties include whether they produce mostly or all male plants or a mix of female and male plants. Some varieties are carefully bred to be able to resist diseases. Some are bred to be hardy in higher or lower temperatures than others.
One major difference you might notice between asparagus plant varieties is the color of the stalks. Green is a common color, but you might also see plants that produce purple stalks.
Although you can find white asparagus spears in the grocery store or farmers’ market, it’s important to understand that white asparagus isn’t a special type of asparagus. Gardeners use a special technique to produce the white color.
According to Texas A&M University, you can produce white asparagus by depriving the spears of sunlight while they grow. To do that, you cover the growing plants with soil. Without the sun, the plant won’t produce chlorophyll and will be white instead of green.
Fun Facts About Asparagus Plants
Asparagus is thought of as a maritime plant, meaning it will thrive in conditions that are saltier than average. Since high levels of salt in the soil don’t seem to harm asparagus, conventional thinking is that putting a layer of rock or kosher salt on the soil around the plants is a good way to control weeds.
As the Wisconsin Gardener notes in this video, it’s definitely not a good idea to toss salt around your asparagus. While the plant can handle it, the soil can’t. A better way to keep weeds down is to add a layer of mulch around your asparagus.
Another fun fact about asparagus plants is that they contain asparagusic acid. According to Smithsonian Magazine, it’s the only plant that contains it. When you eat asparagus, your body breaks the asparagusic acid down into sulphur compounds that are very fragrant. The scent is most noticeable in urine, although some people either don’t produce any odor or can’t smell it.
If you live in the right area, asparagus can be a plant that keeps on going, year after year, even if you forget about it. With so many varieties available, it’s worth giving asparagus a try in the garden.
Photo by Serres Fortier licensed under CC BY 2.0.