When To Plant Asparagus In Oregon

If you’re wondering when to plant asparagus in Oregon, timing is everything for this perennial favorite. Getting it right means a bed that produces for 15 years or more, so let’s break down the optimal schedule for your garden.

For Oregon gardeners, the answer revolves around soil temperature and winter dormancy. The best time to plant asparagus crowns is in early spring, as soon as the soil is workable. This is typically from late March through April in the Willamette Valley and western regions.

In colder, higher-elevation areas like Central or Eastern Oregon, you might need to wait until late April or even early May. The key is that the ground has thawed and dried out enough that it’s not a muddy clump. Planting too early in cold, wet soil can cause the crowns to rot.

Why Spring Planting is Essential

Asparagus plants need a long growing season to establish their deep root systems before winter. Spring planting gives them this full season. They also require a period of winter dormancy, which Oregon’s climate provides perfectly.

Fall planting is generally not recommended here. Our wet winters can saturate the soil and damage or rot the crowns before they get established. Sticking with spring gives your plants the best shot.

Understanding Your Oregon Climate Zone

Oregon’s diverse climates mean your timing might shift slightly. Here’s a quick zone guide:

Western Valleys (Zones 8a-9a): This includes Portland, Salem, Eugene. Aim for late March to mid-April. The milder winters allow for slightly earlier planting.
Coastal Areas (Zones 8b-9b): The coast has cooler summers. Plant in mid to late April, as the soil takes longer to warm up.
Southern Oregon (Zones 7b-8b): Areas like Medford can often plant in early to mid-March.
Central & Eastern Oregon (Zones 6a-7b): With colder winters and later springs, target late April through May. Always wait for the ground to thaw completely.

Step-by-Step: Planting Your Asparagus Crowns

Once your timing is set, proper planting technique is crucial. Follow these steps for success.

1. Choosing a Site and Preparing the Bed

Asparagus needs full sun—at least 8 hours a day. The site must have excellent drainage to prevent crown rot. This is a long-term commitment, so choose wisely!

Prepare the bed in the fall if you can. Remove all weeds and grasses, as asparagus hates competition. Work in a generous amount of compost or well-rotted manure. Aim for soil that is loose, rich, and deep.

2. Selecting Your Crowns

Purchase one-year-old crowns from a reputable nursery. Varieties like ‘Jersey Knight’, ‘Jersey Supreme’, or ‘Purple Passion’ are excellent for Oregon. Male hybrids often produce more spears.

3. The Planting Process

Soak the crowns in lukewarm water for about 15 minutes before planting.
Dig a trench 12 inches wide and 6 to 8 inches deep. Space trenches 3 to 4 feet apart.
Create a small mound of soil down the center of the trench. Drape the crown over the mound, letting its roots hang down on all sides.
Space crowns 12 to 18 inches apart within the trench.
Cover the crowns with just 2 inches of the excavated soil.

As the shoots grow through the summer, gradually fill in the trench with the remaining soil. By the end of the season, the trench should be level. This method encourages strong root development.

Caring for Your New Asparagus Bed

The first two years are about patience and building plant vigor. Do not harvest any spears in the first year. In the second year, you can pick a few for just 2-3 weeks.

Regular watering is key, especially during dry summer spells. A consistent mulch layer of straw or compost helps retain moisture and suppress weeds, which is vital since asparagus can’t compete well.

Fertilize in early spring as growth begins and again after the final harvest in early summer. Use a balanced organic fertilizer or compost. Keep an eye out for asparagus beetles, especially in western Oregon; hand-pick them off.

The Harvest Timeline in Oregon

Your patience pays off in year three. You can begin a full harvest season, which lasts 6 to 8 weeks. Start cutting spears when they are about 6 to 8 inches tall and still tight at the tip.

Stop harvesting by early to mid-June in most parts of Oregon. This allows the plants to grow their ferny foliage, which photosynthesizes and stores energy for next year’s crop. Let the ferns stand until they turn brown in the fall before cutting them down.

Common Mistakes to Avoid

Planting too deep: Burying crowns too deeply smothers them. Follow the trench method.
Harvesting too soon: This is the biggest error. It weakens the plant for future years.
Poor site selection: Not enough sun or poor drainage leads to failure.
Neglecting weed control: Weeds will easily outcompete young asparagus plants.

Remember, a well-cared-for asparagus bed is a fantastic investment. The initial wait is worth it for decades of fresh, early-spring harvests. With Oregon’s ideal climate for this crop, your efforts are sure to be rewarded.

FAQ: Asparagus Planting in Oregon

Can I grow asparagus from seed in Oregon?
You can, but it adds an extra 2-3 years before harvest. Most gardeners prefer crowns for a head start. If starting from seed, sow indoors in late winter.

What if I miss the spring planting window?
It’s better to wait until next spring. You can sometimes find potted asparagus plants in summer, but they’ll need extra care to establish. Fall planting is to risky with our wet winters.

How do I protect my asparagus over Oregon’s winter?
After cutting back the dead ferns in late fall, apply a thick layer of mulch (like straw or compost) over the bed. This protects the crowns from temperature swings and adds nutrients.

Does asparagus grow well on the Oregon coast?
Yes, but the cooler soil means a slightly later start. Choose a sunny, sheltered spot and be prepared for a slower establishment phase. Good drainage is even more critical with coastal rains.

When should I divide my asparagus plants?
Asparagus rarely needs division. If a bed becomes overcrowded after many years, you can carefully divide crowns in very early spring before growth starts. This is usually not necessary for 10-15 years.