Growing Asparagus in Your Vegetable Garden
April in Wisconsin is the time to start growing Asparagus patches! This long-lived perennial vegetable, once established, will provide 15-20 years of spring harvest. You can find Asparagus at Johnson’s Gardens in Spring as bareroot crowns. We also carry potted plants later in the season.
Starting with a weed free, nutrient rich, loose planting bed will give you a good foundation for many years of harvest.
- Select a site in full sun.
- Work in generous amounts of organic matter.
- Dig a trench 12” deep and 12” wide.
- Fill the bottom of the trench with nutrient rich organic matter.
- Create a 6” high mound every 18”-24” in trench.
- Select male varieties of Asparagus for planting (e.g. Jersey Knight or Jersey Giant) as they produce much higher yields since they don’t have to put energy into producing seeds.
- Set a single Asparagus crown on top of each mound, spreading the roots around the top of the mound. The crowns should be about 6” below soil level.
- Cover each crown with 2” of soil and fill in trench between mounds to same level.
- Water thoroughly.
- As plants grow, continue to add more rich organic soil until the trench has been filled back up, level with the soil surface.
- Asparagus likes moisture so keep bed well-watered.
- Asparagus will not tolerate competition, so it is important to keep the bed weed- free.
- Mulching the bed with clean straw will retain soil moisture and discourage weed growth.
- Fertilize each spring with a balanced organic fertilizer.
- Do not harvest any spears the first two years. This allows the plant to put all of its energy back into establishing a robust root system.
- Starting the third year, apply the 2-4-6 week rule. Harvest for two weeks the third year after planting, four weeks the fourth year, and six weeks every year after that.
- Spears should be harvested when they are about the width of a pencil and around 6” high. To harvest spears, cut them off just above the soil level. Continue harvesting until plants produce only skinny spears, less than a half inch in diameter.
- Once you stop harvesting the spears will grow into tall feathery plumes of foliage, reaching 4’-5’ in height. Leave this top growth in place through the growing season and through the winter, cutting the dead stems down to ground level in spring to start the cycle again.