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Growing asparagus in home gardens

A quick guide to asparagus

  • An asparagus plant can last 15 years. Choose its spot in the garden carefully.
  • You can start asparagus from seed or from one-year-old roots, called crowns.
  • Crowns grow vertically and horizontally. Planting at the right depth is important.
  • Good soil moisture is important at planting for good root and fern growth.
  • Begin harvest two years after planting crowns, and three years after planting seeds.
  • Harvest spears until June 30, then allow the large feathery ferns to develop.

Asparagus is a sign of spring 

Bunches of green asparagus spears at a market

Asparagus (Asparagus officinalis) is one of the earliest harvested vegetables each spring. Asparagus spears are crisp, tender and flavorful. The asparagus harvest season lasts about 6 to 8 weeks, from early May to late June in Minnesota. In the peak of asparagus season, asparagus spears can grow up to 2 inches per day, producing bountiful harvests for gardeners to enjoy.

How asparagus grows

Asparagus is a unique crop. It is one of the few perennial vegetables grown in Minnesota; others include horseradish and rhubarb.

The edible parts of the plant are called the spears. These are technically the stems of the plants. The spears emerge from underground buds at the base of the root system. These buds and roots are called “crowns.” If spears are left to grow, they develop leaves and are called ferns. Asparagus harvest is only two months instead of the entire season because the plants need time for the ferns to grow and build up energy for the next year.

The fern creates energy that will be stored in the underground portion of the plant to produce the following year’s spears. It is important to take care of the ferns even after the harvest is over to make sure you will have good future harvests.

Soil pH and fertility for asparagus

Asparagus grows best in well-drained soils with a pH between 6.5 to 7.0 and does not tolerate extremely acidic soils. It can grow in heavy, medium, or sandy soils, as long as the soils must be well-drained and do not exhibit pooling water after rains.

Before planting asparagus, have your soil tested to see if the soil has the right amount of nutrients for asparagus to thrive. Add recommended fertilizer based on the soil test results. It is best to add part of the fertilizer in the fall or spring before planting, but about half of the phosphorus and potassium should be added at the time of planting. Nitrogen should be added after planting, once the crowns begin growing.

If you don't have a soil test report, the typical garden fertilizer rate for asparagus is to apply 1 to 1.5 pounds of 10% nitrogen, 10% phosphorus, and 10% potassium fertilizer (10-10-10) per 100 square feet before planting.

Once an asparagus patch is established, it is best to test the soil every three years and follow the test recommendations before adding nutrients. After the asparagus patch is established, fertilizer, compost or composted manure can be added either in early spring before spear emergence, or after harvest in late June or early July. Only add these inputs if they are needed according to the soil test.

Add the fertilizer alongside the row of plants and scratch it in lightly. Do not allow the tool to penetrate the soil more than an inch deep, to avoid harming the underground portions of the plants.

If your soil test shows that the garden is high in phosphorus, use a low-phosphorus fertilizer such as 32-3-10, 27-3-3, or 25-3-12, or use a non-phosphorus fertilizer such as 30-0-10 or 24-0-15 at the rate of a half pound per 100 square feet. Avoid adding unnecessary amounts of phosphorus to the soil beyond what the soil tests recommend. Continuous use of high phosphorus fertilizers such as 10-10-10 or 15-30-15, or high rates of manure or compost can result in phosphorus buildup in the soil that impacts soil and plant health over time.

Do not use any fertilizer containing an herbicide (such as a "Weed and Feed" product), as it may kill your vegetable plants.

Selecting plants




How to keep asparagus healthy and productive


Managing pests, diseases, and disorders

Many things can affect asparagus spears, roots and ferns. Changes in physical appearance and plant health can be caused by the environment, plant diseases, insects and wildlife. To address what you’re seeing, it is important to make a correct diagnosis. 

You can find additional help identifying common pest problems by using the online diagnostic tools or by sending a sample to the UMN Plant Disease Diagnostic Clinic. You can use Ask a Master Gardener to share pictures and get input.


Authors: Cindy Tong, Extension horticulturist, Marissa Schuh, Extension educator, Jill MacKenzie and Annie Klodd

Reviewed in 2023

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