How do I plant asparagus?

Because asparagus are perennial plants in the vegetable garden, you want to take the time to prepare the soil deeply and add a lot of organic matter. Choose your site in the garden carefully as well; pick one at the north or west side so you don't shade your shorter vegetables. We get a lot of questions about how to get weeds out of asparagus, so make sure the planting area is as weed free as possible to begin with.

Select one-year old crowns of the newer male varieties like Jersey Giant, Jersey Prince, or Jersey Knight. You will probably need to mail order them; make sure the company you select will send the crowns at the right time for planting. You shouldn't plant until the soil is at least 50 degrees and you don't want to have to hang on to the crowns for too long and risk them either drying out if stored too exposed or rotting if stored too wrapped up.

When the time is right for planting in April or May, dig a trench around 6 inches deep. You can add more compost at this time or phosphate. Place the crowns in the trench about 1½ feet apart. Rows should be a good 5 feet apart. Traditionally, the crowns are then covered with 2 inches of soil. When the shoots emerge, 2 additional inches are added being careful to keep some of the new growth exposed. This process is repeated until the soil is filled to the top of the trench. While most people still plant asparagus this way, new studies have shown that this is not necessary. Either way, do not compact the soil over the crowns.

OK, you've chosen a site, prepared the soil, and planted your crowns. Now comes the hard part: you can't harvest this year. You have to wait until next year and even then, do not pick every spear. This patience will reward you with a strong, healthy, long-lasting stand of asparagus. 

For more information:

Asparagus- Watch Your Garden Grow - University of Illinois Extension

Everything About Asparagus - Michigan Asparagus Advisory Board

Can you sprinkle rock salt on the base of asparagus to keep weeds out of it?

Asparagus has a higher tolerance for salt in the soil that many weeds do, so an old practice used to be to pour the salty water from the ice cream maker over the asparagus bed to kill weeds.  However we don't recommend this now, because too much salt in the soil will eventually kill the asparagus, too!  The best option is to use mulch and Preen to control the annual weeds.

Or here's another technique used by commercial growers. At the last harvest of the season cut down all the spears, so there's no foliage or anything above the ground. Rake the soil over the top of the spears. Then overspray the entire planting with glyphosate (RoundUp). Glyphosate becomes bound by the soil particles when it hits them, so will not damage the crowns below ground.  This will control annuals and tough perennial weeds.  The spears will then re-emerge from the soil and not be damaged by the glyphosate at all.  Apply some mulch to help with the weed control, then Preen.