Asparagus is a flowering perennial with fern-like foliage and early shoots that are harvested as lovely spring vegetables. Its emergence from the ground in early spring makes it the first harvestable vegetable of the year and opens the growing season gates for home gardeners.
It takes some patience for this plant to get established in the garden, but after a few years, you’ll have a high-yielding plant that will keep giving for well over twenty years. Follow this guide on how to plant and grow asparagus so that you can enjoy robust harvests of delicious, nutritious, and tender spears for many years to come.
Ideal Soil Composition & pH for Growing Asparagus
Asparagus grows best in loose, fertile, loamy soil that is well-draining. When planting asparagus, the ground should be free of rocks and claylike clumps. Amend your native soil with plenty of organic matter and well-decomposed compost and remove any debris from the soil that can impede plant roots’ spread.
Asparagus plants grow best when the soil is slightly acidic to neutral, with the target being between 6.5 and 7.0 on the pH scale. This vegetable may not thrive if the pH is either too low or too high, as this may impact how readily available the essential nutrients are for the plant.
If you are unsure of your soil quality or pH, visit your local extension office with a soil sample. The experts will test your soil, give you the breakdown of what soil type you have, and suggest what organic soil amendments are necessary for peak growing performance.
Where to Plant Asparagus
Select a spot in your garden that receives full sun. Asparagus plants need lots of sunlight to grow to their fullest potential. Ensure that asparagus plants receive a minimum of six to eight hours of direct sunlight per day.
Asparagus requires climates where the winter temperatures dip below 40 degrees Fahrenheit and have summer temps that soar above the 75-degree mark.
Where to Grow Asparagus
Growing asparagus is best done in rich, loose soil. They can be grown in-ground in backyard gardens or in raised garden beds. If your soil is dense, planting in a raised garden bed or large container may be your best bet for successfully growing asparagus. For in-ground planting, be sure to amend your soil with lots of well-decomposed composed and other organic matter before planting.
Asparagus can be grown in:
- Raised Beds
Starting Asparagus from Seed vs. Crowns
Asparagus can be planted from seeds or purchased and planted as crowns. Buying dry root asparagus crowns is the preferred method for growing asparagus because planting can ensue right away, provided that planting conditions are appropriate. Starting asparagus from seeds can take several years for the plants to establish themselves.
How to Plant Asparagus Seeds
- It can take three weeks for asparagus seeds to germinate.
- Sow seeds 12 to 14 weeks before the last frost date in your area.
- Sow seeds ¼ inch deep in the seed starting mix.
- Harden off seedlings in a protected area for at least one week before planting outdoors.
- Weed the garden beds regularly as seedlings get established.
Planting Asparagus Roots
- Amend soil with organic matter and compost and loosen the soil before planting.
- Add an organic starter fertilizer which will add beneficial soil microbes to the soil.
- Dig trenches in the soil that are 6-10 inches deep and 4-5 inches wide. Allow soil to hill up between trenches.
- Find the midpoint of the roots of your asparagus crown and gently add separation so that half branches out to one side and a half to the other. It will look a bit like an octopus.
- With the crown facing upward, lay the roots out longways in the trench.
- Place the next crown 12-18 inches apart, allowing some of the roots to overlap. Continue planting this way within the trench.
- When all crowns are planted, gently cover each trench with only 2-3 inches of loose soil, allowing hilling to remain between rows.
- Water in well.
- The first watering will settle the soil. Assess the trenches and ensure that the plant roots still remain covered. Add a little more soil as needed to cover the roots.
- As the asparagus starts to grow, you can gradually move small amounts of soil from the hills and tuck it in around plants until the soil is ultimately level and plants are established.
- Once the soil is level, add a couple of inches of mulch to the garden bed to suppress weeds and retain moisture.
Ideal Plant Spacing for Growing Asparagus
When growing asparagus, plant asparagus crowns 12-18 inches apart from each other in rows that are 8-10 inches apart.
How to Water Asparagus
Keep asparagus plants well-watered, especially during the first year until they’re well-established. Give plants a good soaking of water once a week during the spring months and twice a week during the heat of summer.
Nutrients Needed for Growing Asparagus
Asparagus is a heavy feeder of nutrients. When growing asparagus, be sure to give plants their best start by amending soil with well-decomposed compost and rich organic matter upon planting. Side-dress with fertile compost in the fall to give plants adequate nutrient supply for the following year’s harvest.
Fertilize early each spring with a balanced organic fertilizer that contains phosphorous. Avoid fertilizers that are heavy on nitrogen.
How Long Does it Take for Asparagus to Grow?
How long does it take for asparagus to grow? The time to harvest asparagus depends on how mature the crowns were when you planted them. Do not harvest asparagus until plant crowns are at least three years old. Asparagus plants need time to develop and feed their root systems in order to produce abundantly later on.
You can expect to harvest lightly on year three, only reaping 1/3 of the harvestable crop from the plant. By the fourth year of growth, you can enjoy a bountiful harvest of nutrient-rich spears.
- In the springtime, harvest spears when they are 6 to 10 inches tall and before buds begin to open.
- Break off or cut spears at their bases at ground level.
- Continue harvesting spears for six to eight weeks.
- Once midsummer rolls in, allow the plant to grow unharvested to gather the nutrients that it needs to grow for the following season.
- If plants are not producing well, they may need more time to mature. Allow the plant to grow and store energy for future production.
- If any spears attain a height of 10 inches or more, allow them to remain on the plant as a source of energy to the root system.
Recommended Asparagus Varieties to Grow
There are many varieties of asparagus plants that yield different colored plant spears and vary in texture and taste. Try some of these tried and true perennial favorites in your garden and enjoy bountiful harvests for many seasons to come.
- ‘Martha Washington’
- ‘Sweet Purple’
- ‘Jersey Knight’