Planting Asparagus

Planting Asparagus

Part of Ep. 1802 Asparagus, Grass & Daffodils

UW-Extension Horticulture Educator Lisa Johnson shows how easy it is to plant asparagus by adhering to a few basic rules. She explains that bare root asparagus is best planted in spring with the roots pointing down in a six-inch trench. Johnson also recommends choosing male plants, which produce more spears. Good varieties include Jersey Night, Jersey Supreme, Jersey Prince and Purple Passion.

Premiere date: Mar 31, 2010

TRANSCRIPT+
Wisc Gardener Transcript: 

Shelley:
Asparagus is a very popular spring vegetable and it's very easy to grow with a few easy tips. I'm with Extension horticulture educator, Lisa Johnson. And we're going to share some of these tips. We are outside of Dane County Extension Horticulture Building in the children's garden. And Lisa, what do we need to do to make asparagus a successful crop? Time of year, that's probably the most important thing.

Lisa Johnson:
Okay, you can plant your asparagus and usually it's going to be bare root like this somewhere between April 15 and May 15.

Shelley:
So it is a spring crop. 

Lisa:
Yes, it is a spring crop. Again, usually you're going to get it bare root like this easy to find in most of the garden centers. 

Shelley:
Is there an issue, as far as planting it right side up? 

Lisa:
Yes, there is. You want to make sure that the roots are not going this way. 

Shelley:
This is bad, do it that way.

Lisa:
Do it this way, roots should be pointing down. Those pointy tips are where the buds and the spears are going to come out. You can see there are actually some coming in. 

Shelley:
Do it that way! And what about varieties, do we have a lot of choices?

Lisa:
Well, first of all, you want to try and choose a male variety, rather than a female variety because the female variety produces fruit. That takes a lot of energy out of the plant and it could be using that for spear production, so the males tend to be more productive.

Shelley:
And the fruit is the pretty red berries that we sometimes see in floral arrangements. So we don't want that, we want the nice juicy spears.

Lisa:
Right. You can choose varieties like Jersey Night, Jersey Supreme, Jersey Prince. There are even some purple ones, Purple Passion, for example, which is one of the ones we have right here today.

Shelley:
Now, this will actually be purple as it grows.

Lisa:
Right, unfortunately, it does turn green once you cook it.

Shelley:
Okay, but in the garden we could actually put it some place for its ornamental color. 

Lisa:
Sure could.

Shelley:
And this is a perennial? 

Lisa:
Yes, you can have asparagus stay productive 15 to 20 years.

Shelley:
We could plant it somewhere and enjoy the color? Okay, so this is a hardy perennial. 

Lisa:
Yes, it's hardy up to -40 degrees. It's hardy throughout the entire state of Wisconsin.

Shelley:
Okay, well, let's get planting then. What do we need to do to make it work? 

Lisa:
Well, we have dug a trench here. You want it about six inches deep. They used to recommend about eight inches deep. However, they found that it's more productive this way. You want the site to be in full sun at least six hours a day. And when you put your asparagus in, you want to make sure to spread out the roots.

Shelley:
Put the little tips upright.

Lisa:
Put the tips up and they should be about 18 inches apart.

Shelley:
So in a trench like this you'll only get two plants.

Lisa:
Right.

Shelley:
I'm going to start filling it in. Am I filling it in gradually or am I just going to fill it up? 

Lisa:
The old recommendation was to fill it gradually, However, new research has shown that you really don't have to do that. And as far as fertilizing goes I have not amended the soil at this point. You do want to make sure that —

Shelley:
Be gentle around the tips, I assume.

Lisa:
I have not added any fertilizer to the soil. In the southern part of the state, we tend to have excessive levels of potassium and phosphorous.

Shelley:
Oh, yes.

Lisa:
And the asparagus plant likes plenty of both. So here we don't have to worry about that. It also likes a pH between 6 and 6.8. We might be a little alkaline here, so you might have to add some iron sulfate if the pH is excessive. Up north, you have the opposite problem.

Shelley:
Right.

Lisa:
So you should get a soil test to find out what you need. And you do need some nitrogen added.

Shelley:
Okay, but do I bury that?

Lisa:
Yes, you do.

Shelley:
I cover this all the way up to the top.

Lisa:
Yes, to the original soil level.

Shelley:
Okay, when am I going to eat? Not this year.

Lisa:
Not this year, but next year the asparagus should come up about the time the forsythia starts to bloom, and you can harvest that first year. Only for about three weeks, and you want to make sure that you start doing it when they're a little bit bigger than pencil size. Next year, however your harvest date is going to increase to four to six weeks. And the year after that, the third year it might be six to eight weeks.

Shelley:
So each year a little bit longer and more crop then, too. Okay, so we're harvesting more each year. What about weed control? There's a myth.

Lisa:
Yes, there is! There's a myth that you should use salt. 

Shelley:
On the soil around the plants.

Lisa:
Right, and while asparagus is salt-tolerant the soil is not. 

Shelley:
No, it's bad!

Lisa:And it actually ruins the structure of the soil.

Shelley:
So, no salt. Mulch?

Lisa:
Mulch would be great, or cultivating the weeds out.

Shelley:
Pulling them out.

Lisa:
Yes, the second year you can use a pre-emergent weed control if need be.

Shelley:
Don't destroy the soil with salt. Well, I can't wait to eat this, thanks, Lisa.

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