Planting Asparagus Seed – How Do You Grow Asparagus From Seed

Asparagus Seed Growing on Branch
asparagus seed
(Image credit: joloei)

If you are an asparagus lover, chances are good that you would like to include them in your garden. Many gardeners buy established bare root stock when growing asparagus but can you grow asparagus from seeds? If so, how do you grow asparagus from seed and what other information on asparagus seed propagation might be helpful?

Can You Grow Asparagus from Seeds?

Asparagus is often grown from bare root stock crowns. The reason for this is that growing asparagus requires patience. Crowns take three growing seasons before they are ready to be harvested! Even so, this is significantly faster than if you try growing asparagus from seeds. 

That said, yes, asparagus seed propagation is very possible and a little cheaper than buying crowns. Asparagus seeds, or berries, turn bright red in autumn. Once the tops fall over, the tops can be collected and hung upside-down in a warm, dry area for about a week or so to ripen. 

To catch the seeds once completely dried, keep a bowl beneath them or gently tie a brown paper bag around the tops when hanging. These seeds can then be used for planting asparagus. Likewise, you can purchase them from reputable suppliers.

How Do You Grow Asparagus from Seed?

Asparagus (Asparagus officinalis) is a hardy perennial suited to USDA zones 2 to 8 and is native to western Europe. This perennial can remain viable for 10 to 20 years, so choose your garden site carefully. Asparagus needs a soil pH of between 7.0 and 7.2 in fertile, well-draining soil. 

So how do you go about planting asparagus seeds? There’s no trick to growing asparagus from seeds, just be patient. It’s recommended that you start asparagus seeds indoors or in a greenhouse in mid-February to May under bright lighting. Soil temperatures for seed germination should be between 70 and 85 degrees F. (21-29 C.). Soak the seeds for a couple of hours, then plant each seed ½ inch (1 cm.) deep in sterile soil, in individual 2 inch (5 cm.) pots. 

They should sprout anywhere between two and eight weeks from planting asparagus seeds. Seedlings are ready to transplant when they are 10 to 12 weeks old and all danger of frost in your area has passed. Space the transplants 18 inches (46 cm.) apart in rows set 3 to 6 inches (8-15 cm.) apart. 

If you want thinner spears, space the transplants 8 to 10 inches (20-25 cm.) apart, with the plant set 4 inches (10 cm.) deep. If you like thicker spears, plant them 12 to 14 inches (30-36 cm.) apart and set 6 to 8 inches (15-20 cm.) deep. Consider planting your new asparagus babies near your tomatoes.

Asparagus repels nematodes that attack tomato plants while tomatoes repel asparagus beetles. A very symbiotic relationship, indeed. As the plant grows, cover the crown with soil and keep it moist with 1 inch (2.5 cm.) of water per week. Fertilize in the spring with 1 to 2 cups (250-473 ml.) of complete organic fertilizer per 10 foot (3 m.) of row and dig in gently.

Remember, don’t harvest the plant until its third year; allow the plant to set ferns and redirect its energy back into the plant. Cut the ferns down to 2 inches (5 cm.) tall in the late fall. In the plant’s third year, you can begin regularly harvesting the spears. The season usually lasts around 8 to 12 weeks.

Cut the asparagus spears 1 to 2 inches (2.5-5 cm.) below the ground, and at least 2 inches (5 cm.) above the crown using a sharp knife or asparagus harvesting tool.

Amy Grant

Amy Grant has been gardening for 30 years and writing for 15. A professional chef and caterer, Amy's area of expertise is culinary gardening.