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Fresh green asparagus spears close up
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When to plant asparagus in Cottage Grove, OR

Plant asparagus crowns in Cottage Grove Mar 27 – May 8.

Moderate Plant dormant crowns

Difficulty
Moderate
Sun
Full sun
Spacing
12 to 18 inches apart
Planting depth
In a trench 6 to 8 inches deep, covered gradually as the spears grow
Frost
Hardy perennial; comes back every year
First harvest
Light picking in year two; full harvests from year three

Why these dates

Cottage Grove's typical last spring frost is April 24. As a hardy perennial, this crop can go in about 4 weeks before that.

West-side valleys. The Willamette Valley, Puget Sound and southern Oregon valleys. Long frost-free seasons, but soil stays cold and wet into May, so warm crops wait for warm soil, not just the last frost.

How to grow asparagus in Cottage Grove

  1. Pick a sunny spot with soil that drains well, and mix in an inch or two of compost.
  2. Plant asparagus crowns Mar 27 – May 8, 12 to 18 inches apart. In a trench 6 to 8 inches deep, covered gradually as the spears grow.
  3. Fill the trench in gradually as the shoots grow. Keep the bed weeded, and cut the ferns down only after they turn brown in fall.
  4. Harvest: Snap spears at soil level when they're 6 to 8 inches tall. Stop picking when new spears are pencil-thin, and let the ferns grow.

Key numbers

Growing notes

What makes the difference in Northwest gardens, in plain language.

Start with the right bed

An asparagus bed stays put for a couple of decades, so preparation pays off. Choose full sun and soil that drains well, since crowns rot in waterlogged ground. Asparagus likes a near-neutral pH of about 6.5 to 7.5; many west-side soils are more acidic and benefit from lime worked in before planting. Clear out perennial weeds like quackgrass and bindweed completely first; they're almost impossible to remove once crowns are in.

All-male varieties like Jersey Knight and Millennium produce more spears because they don't spend energy on seeds.

Why the ferns matter

Every spear you pick is food the crown stored the year before. After the harvest window ends, the spears grow into tall ferns that make food through summer and send it down to the roots for next spring. That's why you don't pick the first year, pick only a couple of weeks the second year, and why you leave ferns standing until they turn brown in fall.

Feed with compost or a balanced fertilizer after harvest ends, when the ferns are building next year's crop.

Beetles, east and west

Asparagus beetles, small blue-black and orange insects, chew spears and lay dark eggs on them, and their gray larvae strip the ferns. Hand-pick adults in cool mornings, rub off eggs and cut brown ferns in fall to remove their winter cover.

Asparagus does especially well in eastern Washington and Oregon, where hot summers grow strong ferns and cold winters give a full dormancy. West-side beds produce well too, just a little later, and good drainage matters more there.

Common questions

When is the last frost in Cottage Grove, OR?

Typically April 24. In 9 years out of 10, frost is over by May 10. These are 1991–2020 NOAA climate normals for Cottage Grove.

Is it too late to plant asparagus in Cottage Grove?

The spring planting window runs through May 8. Potted plants can still go in later if you water them faithfully through their first summer. Fall planting also works well here.

How long until I can pick asparagus?

Light picking in year two; full harvests from year three. Snap spears at soil level when they're 6 to 8 inches tall. Stop picking when new spears are pencil-thin, and let the ferns grow.

Why are my asparagus spears so thin?

Thin spears usually mean a young bed, a crown that was over-picked, or weak ferns the previous summer. Stop picking when spears drop to pencil-thickness, feed after harvest and let the ferns grow freely to rebuild the crowns.

When should I cut back asparagus ferns?

Wait until they turn yellow or brown in fall, after the plant has moved its stored food down to the crowns. Cutting them green weakens next year's harvest. Removing old ferns also takes away a winter hiding place for asparagus beetles.

Can I harvest asparagus the first year?

It's best not to. First-year crowns need every spear to grow ferns and build roots. Pick lightly for about two weeks in year two, then harvest fully for six to eight weeks from year three on.

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