Are you wondering whether asparagus spreads? If so, you are not alone. Many gardeners would like to know so they can plan ahead with proper spacing.
So, does asparagus spread? Yes, asparagus will spread as it grows. Asparagus roots can spread out up to 6 feet (1.8 meters) underground. Asparagus ferns (mature spears with foliage) can spread out 3 feet (90 centimeters) above ground. An older, more mature asparagus plant will send up more spears from its larger crown and energy reserves.
Of course, you don’t have to wait for asparagus to spread. You can buy crowns or seeds and plant more asparagus. Either way, you will have to be patient, since asparagus needs time to grow enough so that you can harvest spears.
In this article, we’ll look into how asparagus spreads and how to propagate asparagus. We’ll also answer some common questions about asparagus plants. Let’s dig in.
Does Asparagus Spread?
Yes, asparagus plants will spread as they grow. From humble beginnings (seeds or small crowns), asparagus plants can grow quite tall and wide.
The roots of a mature asparagus plant can spread out 6 feet (1.8 meters) underground. Above ground, the foliage of ferns can spread out 3 feet (90 centimeters).
With more spears that have larger foliage, asparagus plants are able to produce more energy from photosynthesis. This energy is stored in the plant’s roots for growth in later years.
How Far Apart Do You Plant Asparagus Rows?
Since asparagus does spread, you will need to leave enough space between plants. Cornell University suggests leaving 10 to 18 inches (25 to 45 centimeters) between plants.
Leave 4 feet between asparagus rows. This gives you space for watering, fertilizing, weeding, and harvesting during the season.
Leaving enough space between rows also makes it easier to walk through your garden. That way, you can move without stepping on your asparagus plants or bending their spears.
If you want to create more asparagus plants, there are a few ways to do that! Let’s get into the details now.
How to Propagate Asparagus
You have 3 options if you want to propagate asparagus to get more plants:
- Option 1: Grow from Seed (takes more time before you can harvest spears)
- Option 2: Crown Division (more risky, since crowns are more likely to die if split and transplanted)
- Option 3: Buy crowns from a nursery or seed catalog (most expensive, but also lowest risk)
The Cooperative Extension does not recommend dividing the roots to get more asparagus plants. This is because asparagus plants do not transplant well, due to their large and sensitive root system.
Let’s take a closer look at each of the three methods you can use to grow more asparagus plants.
Method 1: Grow from Seed
Growing asparagus plants from seed takes a bit more time and patience than growing from crowns. However, it is more cost-effective, and you can start a good number of seeds at one time.
There are two ways to get asparagus seeds. One way is to buy seeds from a seed catalog. For example, Johnny’s Selected Seeds has seeds available, like the Millennium Asparagus.
The other option is to harvest seeds from an existing asparagus plant. If you don’t have one of your own, maybe you can harvest seeds from a friend’s asparagus plant.
First, you need a female asparagus plant (yes, there are male and female plants!) Female plants will produce red “berries” (containing seeds) later in the growing season.
As asparagus spears reach maturity, the tips open up and expand. At this point, the spears spread out wider and start to look like ferns.
Eventually, red berries will form on the fern-like female asparagus spears. Each of these berries contains a few asparagus seeds.
If you harvest these red berries, you can save the seeds inside for planting. For more information on how to do this, check out this article on asparagus berries from A Veggie Venture.
No matter how you get your asparagus seeds, you will need to plant them properly.
When planting your asparagus seeds, place them 2 inches (5 centimeters) apart, and bury them 0.5 inches (1.25 centimeters) deep.
Asparagus seeds germinate best at a temperature of about 75 degrees Fahrenheit (23 degrees Celsius).
Asparagus seedlings should be transplanted outside after the last frost date in your area. You can use this frost date calculator from the Old Farmer’s Almanac to find out the date in your area.
When you transplant asparagus seedlings, plant them in a long furrow about 6 inches (15 centimeters) deep. Leave at least 10 inches (25 centimeters) between plants, to allow room as they grow and spread.
Remember that starting asparagus plants from seed means waiting a longer time until you can harvest spears.
Method 2: Crown Division
If you don’t want to wait for asparagus berries to grow, then you can try crown division. Of course, you will need existing plants to do this.
Before you begin, realize that you may lose any plants whose roots you dig up and divide. The shock of this is enough to kill the plant.
If you still want to try it, then wait until fall, after the asparagus ferns die back. Usually, this happens after at least one fall frost, when the plants start to go into dormancy.
While the ground is still soft enough to work, dig up the roots of the asparagus plant. Then, cut the roots into separate pieces.
Make sure that each piece of plant has a good portion of the roots. You can replant immediately, or in the spring.
According to the South Dakota State University Extension, it is possible to spread diseases in your garden this way. If an asparagus plant has a disease and you split it in two, then you have two plants with the disease in your garden!
Remember that it is challenging to keep asparagus alive after transplant. This is especially true if you damage the roots, or if you move the plant at the wrong time.
Method 3: Buy Crowns
If you buy 1 year old asparagus crowns from a seed company, then you have a much better chance of successful transplant.
The reason is that older plants have a larger root system. This larger root system is more prone to damage during transplant.
Most reputable seed companies will certify that their stock is disease free. You can buy Millennium F1 Hybrid Asparagus crowns from Johnny’s Selected Seeds.
Planting asparagus crowns is similar to the process for planting seedlings. Johnny’s has more detailed information at the link above, under “”Growing Information”.
When you plant asparagus crowns, put them in a trench about 10 inches (25 centimeters) deep. Dig the trench wide enough so the roots can sit comfortably inside without being bent out of place.
Plant the asparagus with the buds pointing up. Then, cover with a few inches of soil.
As they grow, cover them with more soil throughout the season until the trench is level with the ground.
Can You Move Asparagus Once Planted?
You can move asparagus once it is planted, but the plant may not survive! The older and more established the root system, the more chance of damage when digging and transplanting.
If you have an older asparagus plant that is producing well, leave it alone if possible. Only attempt to transplant if you really need to clear out the space where the asparagus lives.
In that case, be fully prepared for the possibility that the plant might not survive! Even if it does, it may not produce as well in the future, due to the shock of being transplanted.
Where is the Best Place to Plant Asparagus?
Ideally, you should plant asparagus in a place with full sun. However, it can tolerate partial shade.
When choosing a location, make sure it is a spot that you won’t need for growing anything else for many years. Remember how difficult it is to transplant asparagus successfully!
The best spot in your garden for asparagus is a place with light, well-draining soil, with a slightly acidic to neutral pH (about 6.5 to 7.0).
If possible, sift the soil to remove rocks, sticks, roots, and other debris to a depth of 12 inches (30 centimeters) or more before planting. This will give the asparagus roots plenty of space to grow.
As your asparagus grows, avoid the temptation to harvest early on! In the first couple of years, the plant will need most of the energy it produces to continue growing.
You should only start harvesting asparagus spears after a year or more of growth. Even then, harvest carefully and don’t be greedy, or else you will slow the plant’s growth.
If your asparagus spears grow tall and fall over, it might not be time to worry yet. The plants may fall over when the spears mature in the fall.
If you are still worried about your plants, I get it! For more information, check out my article on why your asparagus spears are falling over (and how to prevent it).
Now you know how far asparagus spreads and how big it gets. You also know how to get more plants. Which method would you be most likely to try: seeds, crown division, or buying crowns?
I hope you found this article helpful. If so, please share it with someone who can use the information. I hope you get a great asparagus harvest this year and in the years to follow!