In New York City, the mean last spring frost falls between March 23 and April 3 (NOAA 1991-2020 normals, Central Park), and bok choy and its relatives can go in soon after. The better window opens in late summer, once the worst heat has passed and the first fall frost is still weeks away. Upstate and Adirondack gardens run on a different calendar, so shift every date below to your own county.
When the soil is warm enough in New York
The date most gardeners want is the last spring frost. At Central Park, NOAA’s 1991-2020 U.S. Climate Normals place the 32°F freeze probability in the 30-to-70 percent band from March 23 to April 3. That is a probability, so a freeze after April 3 can still happen in any given year. Central Park is also a dense urban site. It is a New York City figure, and it does not describe the Hudson Valley, the Finger Lakes or the Adirondacks, where spring frost lingers later.
The frost date is a calendar stand-in for what Asian greens actually respond to, which is soil temperature. Soil warms after the frost risk ends, and a cold, wet March can leave beds chilly well into April. These are cool-season crops, so seed will sprout in cool ground, but slowly, and in cold waterlogged soil it often rots before it emerges. A late spring also shortens the useful window, because lengthening days and warming weather push bok choy, tatsoi and napa cabbage toward bolting.
How do you tell the bed is ready for Asian greens?
Pick up a handful of soil. If it crumbles, the bed is workable. If it holds together as a wet ball or leaves water in your palm, wait. A soil thermometer pushed in to seed depth each morning gives a better read than the calendar, and what you want to see is a reading that has been climbing for several days, not one warm afternoon.
Once the bed passes that test, sow quickly. A spring planting is a race against heat. Fast types such as baby-leaf mustards, mizuna and compact bok choy can be harvested young before summer arrives, while large heading types usually fall behind.
Does upstate New York follow the same calendar?
No. The USDA Plant Hardiness Zone Map (2023 edition, built on 1991-2020 normals) runs from zone 3b to 7b across the state. That system rests on one variable, the average annual extreme minimum temperature. The spread tells you that a gardener in the Adirondacks and one on Long Island are working with very different springs. Treat the city dates as a reference point, then move later as you go north or up in elevation.
For dates and varieties that fit your county, the county office of Cornell Cooperative Extension is the best first call. Staff there know which sowing dates have worked locally.
How long the season lasts here
The reference station has a frost-free period between the mean last spring frost (March 23 to April 3) and the mean first fall frost (November 14 to November 27). Which number you land on depends on which ends of the two bands you pair.
That is a long window, and for Asian greens it allows two separate crops. A spring sowing goes in as soon as the soil is workable and comes out before midsummer. After a gap through the hottest weeks, a second sowing starts in late summer and carries into fall. For most of these greens, the fall crop is the better one. Cooling nights and shorter days suit them, and bolting stops being the main worry.
A long window also lets you stagger. Rather than sowing a whole bed on one day, plant a short row every couple of weeks so the harvest arrives in small, steady batches. The general approach is laid out in Growing Asian Greens: Fast, Cold-Hardy, and Prone to Bolting, and it works well in a city garden where bed space is limited.
With this much time, transplanting is a choice rather than a necessity. Direct sowing is simple and avoids root disturbance, which matters because a check at the root can trigger early bolting in this family. Transplants earn their keep where the window is shorter, as in the colder, higher parts of the state, because they buy a few weeks. If you buy or raise transplants, look at the roots before planting. Seedlings that have circled the cell or pushed out the bottom are already stressed and will bolt sooner. Set them in gently with the root ball intact.
The frost-free count is not the whole story for these crops. Most of them keep growing, if slowly, after the first light frosts, and some of the hardier ones stand much longer. The count mostly tells you how much room there is at the front end for a spring planting and how much extra time a fall crop gets.
Heat and water in New York
Asian greens belong to the second half of the year, so the facts that govern them are the first fall frost and the winter low. At the Central Park station, the mean first fall frost comes between November 14 and November 27. Count back from that to see how late a sowing can still finish. Take the days to maturity on the seed packet, which count from sowing for direct-seeded crops, subtract them from the frost date, and add a generous margin. Growth slows well before frost as days shorten, so a late sowing needs more time than the packet suggests. Late plantings are better filled with baby-leaf types that can be cut small.
The winter low decides the next question, which is whether any of them stand through the cold. The mean daily minimum of the coldest month at the New York City reference station is 27.9°F, which is below freezing but not extreme. Under a row cover or low tunnel, the hardiest types, such as tatsoi and mizuna, can hold through much of a New York City winter. Tender types, including bok choy and napa cabbage, end with the first hard freeze unless they are cut first. An average minimum hides colder individual nights, and upstate gardens run colder still, so covers there need to be heavier.
Summer is the awkward season. Hot, humid spells in the New York area can push a midsummer sowing into bolting, and the number of hot days varies with location. The coast and city run warmer than the Adirondacks. Where the heat is milder, as in cooler upstate summers, a damp season brings its own problems: mildew on the leaves, slow growth and leaf spots, along with slugs hiding in the wet. Giving plants room, spacing them for airflow and watering at the base rather than overhead all keep the foliage drier. Watering in the morning lets any splash dry off by evening.
Steady soil moisture keeps these greens growing evenly. Drip lines or a soaker hose at the root, with a layer of mulch to hold moisture and keep the soil cooler, handle both jobs. Uneven watering invites stress, and stress invites bolting.
Flea beetles chew small holes in young leaves and do the most damage early in the season. A floating row cover set over the bed at sowing is the standard practice, and it keeps off other pests too. Row cover also helps with the rotation problem. Asian greens are brassicas, and so are turnips and rutabagas, so they share their pests and diseases with cabbage, kale and mustard. Planting them where one of those grew the year before means no rotation has happened. Move them to a bed that has been free of the whole family for a few seasons.
Gardeners comparing climates may find the contrast useful. A hot-summer state like Arkansas has a very different calendar, covered in Growing Asian Greens in Arkansas, and the dry, high-elevation conditions in Growing Asian Greens in Utah bring their own timing.
Which Asian greens suit New York
Match the type to the season you have. A short season favors the fastest types. Hot spells favor those given airflow and shade at the root. A humid summer makes disease resistance the first thing to look for on a seed packet.
| Type | Where it fits in New York | What to watch |
|---|---|---|
| Baby-leaf mustards and mizuna | Quick spring and late-summer sowings, and the late plantings that need to finish before frost | Flea beetles in spring; bitterness when stressed |
| Tatsoi | Fall crops and cold-season harvests under cover | Bolts if sown into lengthening spring days |
| Compact bok choy | Early spring and the main fall sowing | Bolts in heat and long days; harvest young |
| Napa cabbage | A fall crop with cool nights | Needs the longest time; most exposed to disease in humid weather |
Choose by type, and pick the specific variety locally. Seed catalogs list dozens of named selections, and they change from year to year. A variety that does well on Long Island may disappoint in the North Country, because the sowing dates, soils and disease pressure differ. Only the varieties trialled near you tell you what works, so ask your county Cornell Cooperative Extension office which have been grown in your area.
Disease resistance is worth reading carefully on a seed packet. In a damp year, a resistant type of any of these greens holds up where a susceptible one yellows and spots. If your garden has grown cabbage-family crops recently, resistance matters even more.
Common questions
Can you sow Asian greens in April in New York?
In New York City, yes, once the soil is workable and no longer waterlogged. The mean last spring frost at Central Park falls between March 23 and April 3, so April is usually past the risk. Upstate, wait longer, and sow fast types that can be harvested before the weather turns hot.
What is the latest you can sow for a fall harvest?
Work backward from the first fall frost. At Central Park the mean first frost falls between November 14 and November 27. Subtract the days to maturity on the packet, counted from sowing, then add a margin because growth slows in short days. Upstate, where frost arrives earlier, the last sowing date moves earlier too.
Will Asian greens survive a New York winter?
Some will, with cover. The mean daily minimum of the coldest month at the New York City station is 27.9°F. Under a row cover or low tunnel, the hardiest types can hold through much of that cold, while tender ones such as bok choy and napa cabbage end with the first hard freeze. Colder parts of the state need heavier protection.
How should you check harvested greens before storing them?
Look over every head or bunch, including the base and crown. Leaves that are slimy or yellowing, a soft patch, a weeping spot or a moldy crown mean the plant should not be eaten, however good the rest looks. Keeping times vary too much to promise, so inspect what you have stored each time you reach for it.