Canadian County OSU Extension Service

Asparagus Care

Asparagus is not your typical vegetable in the garden.  For one, it’s a perennial vegetable and takes a more permanent residence in the garden.  In fact, it’s recommended not to harvest anything for the first 2 years, because it takes that long for it to become fully established.  It’s a crop that will last up to 15 years in your garden.  It’s a dioecious plant; there’s a male plant and a female plant.  It also takes up more room in the garden than most vegetables would. 



asparagus bed


Asparagus is an attractive plant to have in the garden.  The foliage adds a soft texture to your landscape.  It looks much like the asparagus fern, hence the name.  However, it is not the same plant, as all parts of the asparagus fern are poisonous. 


If you buy asparagus crowns at the store to plant in your yard, these have already gone through one year of growth.  This means that when you plant them, you will be able to harvest the asparagus during the second year in your garden.  The first year in your garden is spent growing the foliage, which will in turn put reserves into the plant for good production of spears (the part you eat) the following year.  This is true for every year of growth, so leave the foliage on the plant until it turns golden brown in the late fall, when you will cut it back to the ground and use the foliage as mulch on the bed.  The exception to this rule is when you start seeing berries produce on the asparagus plant, which need to be cut back.  These are the females and rob the plant of energy that could be put into storage for next year’s growth.  The berries are very noticeable, as they are bright red in color.


asparagus crowns


During the first year of planting, it is wise to get the soil tested.  This will tell you what exactly to apply to the soil before planting.  If you know you’re going to plant asparagus in your garden in spring, get the soil tested and amended during the fall before planting.  If you decided a little late that you want to plant asparagus, make sure to get the soil tested and amended at least a few weeks before planting.  The process of getting a soil sample and having it tested takes about a week and a half, so keep that in mind. 


Once the initial recommended fertilizer has been added to the soil, the next fertilizer application time would be in early summer.  This fertilizer need only be nitrogen.  Whatever form of nitrogen you use, be it urea, bloodmeal, etc, make sure to read the label, which will inform you on how much to apply per 1000 square feet.  Nitrogen is the nutrient that produces green lush growth on a plant, and it’s the nutrient that moves quickly through the soil.  Phosphorus and potassium are almost always present in the soil, as they are immobile nutrients.  When looking on a bag of fertilizer, the first number represents the nitrogen percentage, the second number represents phosphorus, and the third number represents potassium. 


plant fertilizer



After the first year in the garden, asparagus needs to be fertilized with nitrogen in early March and after harvest ends in June.  Never apply fertilizer in the fall when plants are gearing up for dormancy.  This creates unnecessary growth late in the season when the plant should be putting energy into hardening off for dormancy.  If fertilized in the winter, the plants will never be able to use it and the fertilizer will most likely be lost to runoff. 


Some other general maintenance tips year after year include mulching with 2-3 inches of compost before weeds emerge, ideally in late fall.  You should also maintain weeds should they emerge.  Be careful not to cultivate the soil with a hoe, as this will disturb asparagus production.  Asparagus is one of the few vegetables that requires you to leave the soil alone.  If you’re having trouble pulling a weed, try watering the weed and then pull it out.  Roundup is an option if you spot treat emerging weeds, being careful not to spray the asparagus. 


If you find that your asparagus spears are thinner this year, you might consider a few things.  Warmer winter temperatures can cause this.  Asparagus requires consistent cold winter temperatures to produce well the following year.  It could also be that your asparagus bed is overcrowded, and in need of being thinned out.  Another reason may be that there wasn’t sufficient foliage growth the previous year, so there wasn’t a lot of energy reserve for this year’s production.  A final possible reason could have been issues with water.  Whether you were battling drought the previous year, or the plants were getting too much water, these scenarios would effect growth the following year.


If you need more information on growing asparagus, please call 262-0155 or email



Oklahoma Cooperative Extension Service offers its programs to all eligible persons regardless of race, color, national origin, religion, gender, age, disability or status as a veteran and is an Equal Opportunity Employer. The information given herein is for educational purposes only.  References made to commercial products or trade names are with the understanding that no discrimination is intended and no endorsement is implied.  Oklahoma State University, U.S. Department of Agriculture, State and Local Governments cooperating.

Document Actions