Pak choi, tatsoi, mizuna, and komatsuna are the safest picks across Washington. They grow fast, like cool weather, and take light frost without complaint. West of the Cascades they can be harvested for most of the year. East of the mountains they fit a spring window and a fall window. Heat-lovers such as water spinach need more warmth than most of the state offers.
The short answer for Washington
Washington has two gardening climates, and the best greens differ in each. At the Seattle reference station, the last spring freeze (32°F) falls between February 27 and March 18, and the first fall freeze between November 13 and November 30. Those are the dates when the odds of a 32°F freeze sit between 30 and 70 percent. The coldest month there has a mean daily minimum of 37.1°F, which decides whether a plant survives the cold here at all. This is western Washington. Eastern Washington is high desert with a far shorter season, so the Seattle window does not carry over.
A mild frost date also does not mean an early planting date. Cold, wet soil and low winter light hold spring sowings back well past the last freeze. The When to Sow Asian Greens in Washington guide covers the timing in detail. Here the question is which type to choose.
| Type | Examples | West of the Cascades | East of the Cascades |
|---|---|---|---|
| Cold-tolerant leaf greens | Tatsoi, mizuna, komatsuna | Excellent, spring through winter | Good in spring and fall |
| Pak choi and bok choy | Compact and baby types | Very good, best from late summer sowing | Good in cool spells, bolts in summer heat |
| Mustard greens | Red and green mustards | Very good in cool months | Good in spring and fall |
| Napa cabbage and daikon | Fall-grown heads and roots | Good from a late summer sowing | Fair, needs a well-timed fall crop |
| Heat-lovers | Water spinach, amaranth greens | Poor, summers run too cool | Possible in a hot summer with steady water |
Which Asian greens grow best in western Washington?
The cool-season leaf greens do best. Tatsoi and mizuna form tidy rosettes and carry on through a mild winter. Komatsuna grows quickly, tolerates both cold and some shade, and gives repeated cuttings. Mustards add a peppery edge. Pak choi is the one to time carefully, because spring sowings often bolt as days lengthen. A sowing from midsummer into late summer tends to give the cleanest heads.
Which Asian greens suit eastern Washington?
Pick the fastest, most bolt-resistant types and aim for the shoulder seasons. Early spring and early fall suit them. The middle of summer does not. Baby-leaf mizuna, tatsoi, and komatsuna finish before heat arrives, and a fall crop sown as temperatures ease is often the better harvest of the two.
What will not work here
Why does sowing at the last frost date fail west of the Cascades?
Because a late-winter freeze date says nothing about soil. A bed that stays cold and soggy through March leaves seed sitting, then rotting, and seedlings that do emerge in low light stretch thin and pale. A sowing made a few weeks later, once the soil drains and warms, usually overtakes an early one. Spring pak choi is the classic casualty, since lengthening days push it to flower before it forms a proper head.
The wet shoulder seasons also punish tight spacing. A fall bed of baby greens sown thickly holds moisture around the leaves, and slugs thrive in that cover. Leave room between plants so air moves, and thin early rather than late.
Heat-lovers are the other failure. Water spinach, Malabar spinach, and amaranth greens want long, hot nights that a maritime summer rarely delivers. They survive, but they barely grow, and they use bed space that a fall crop of mizuna or komatsuna would fill better.
What fails in eastern Washington summers?
Anyone watering once a week. Asian greens have shallow roots and need even moisture, and a hot dry high-desert summer pulls water out of the top few inches of soil quickly. Irregular watering gives bitter, tough leaves and sends plants to seed. Pak choi, napa cabbage, and most mustards bolt in sustained heat, and no amount of watering fully prevents it. Sowing them for harvest in July and August is the usual mistake.
Winter hardiness is the last thing not to carry across the mountains. The 37.1°F figure describes Seattle. Eastern winters are far colder, so tatsoi left standing in a bed through January is not a safe plan without cover. Treat these greens as spring and fall crops, and use a low tunnel or row cover to stretch either end.
What changes across Washington
The state has no single answer. The Growing Asian Greens in Washington overview covers the basics, but the USDA Plant Hardiness Zone Map (2023, built on 1991-2020 normals) puts Washington anywhere from 4a to 9a. That system rests on one variable, the average annual extreme minimum temperature. It tells you about winter survival, and the extreme cold it measures matters less for annual greens than season length and summer heat do.
Zone still helps in two ways. It shows how cold your winters get, which decides whether a fall planting could overwinter. It also hints at how much your growing season differs from the Puget Sound lowlands, which sit at the mild end. Someone in the northeast, the Okanogan, or high in the Cascade foothills sits toward the cold end and should shift everything.
Those shifts are practical. Sow spring crops later, once soil is workable and no longer frozen at depth. Start fall crops earlier, so heads form before hard freezes arrive. Choose the fastest varieties and lean on row cover for the first and last weeks. At higher elevations, cool nights keep leaf greens sweet, and summers there may suit them better than the hot valley floors east of the mountains.
Look up your own location on the USDA map by ZIP code rather than guessing from a neighbor or a regional label. Gardeners in one county can fall in different zones, and the map shows where yours sits.
Where to check this for your own county
The state’s land-grant university runs the best local source. Washington State University Extension has county offices, Master Gardener programs, and regional guidance written for local conditions. Look there for two things: a planting calendar for your county, and any variety trials run nearby.
The calendar matters because Washington’s frost dates vary widely between counties, and extension staff build their dates from local weather records. Trial results matter because they report which varieties actually held up, bolted late, or resisted disease in your area’s soils and summers.
A county recommendation beats a state one every time. The guidance here is the state version. It sets the broad logic, which is cool-season crops, a mild west and a short, hot east, but a county office knows whether your valley holds frost into May or whether your hillside warms early.
If your county office has a Master Gardener helpline or plant clinic, bring a description of your site: sun exposure, soil type, and what you have grown before. That detail lets them match advice to your spot.
Checking this against your own garden
Your own beds outrank every date in this article. Three observations tell you more than a calendar can.
- Soil warmth by feel. Push a hand into the bed in early spring. If the soil feels cold and clammy and clings to your fingers, seed will sit. If it crumbles and feels cool rather than cold, sow. Compare a sunny bed with a shaded one and you will see how much drainage and exposure matter.
- First true leaves. Seedlings first show seed leaves, then the first leaves with the plant’s real shape. Note how long that takes after sowing. A slow stretch tells you the bed is cold or shaded.
- First flower stalk. Watch the center of pak choi or mustard for a rising stalk. When it appears early, that spot heats up quickly or gets long, bright days. Sow the next round earlier or later to dodge it.
Keep notes for a season. Two or three years of dates from your own garden are worth more than any regional table.
Common questions
What is the easiest Asian green to grow in Washington?
Komatsuna and mizuna are the most forgiving. Both grow quickly, handle cool weather, and tolerate some shade. They can be cut young and regrow, which suits a short eastern season and a wet western one.
Can you grow Asian greens through winter in western Washington?
Often, yes. With a coldest-month mean minimum of 37.1°F at the Seattle reference station, hardy types like tatsoi, mizuna, and komatsuna keep growing slowly. Growth slows in low light, so expect small harvests, and cover plants during a hard cold snap.
Why does my bok choy bolt?
Heat and lengthening days trigger flowering. Spring sowings bolt most often, and summer heat east of the Cascades speeds it. Sowing from midsummer into late summer, and choosing compact or bolt-resistant types, gives better heads.
Do I need to start Asian greens indoors?
Rarely. Most are sown directly in the bed and grow fast. Starting transplants can help when spring soil stays cold, or when you want pak choi planted out at the right moment, but direct sowing is the usual method.