Sow Asian greens in Nova Scotia twice: in spring, from mid-April under cover to late May, and again from late July through August for the fall crop. For most types the second sowing does better, because the plants mature in cooling weather instead of lengthening days. The frost dates behind this advice come from Halifax and are averages, so the edges of each window shift with your location and the year.
The short answer for Nova Scotia
The sowing window runs from roughly mid-April, under cover or in soil that has warmed enough to work, to late May for spring crops, and from late July to late August for fall crops. The two anchors are the mean last spring frost, May 7, and the mean first fall frost, October 18. Both come from Environment and Climate Change Canada’s 1981-2010 normals for the Halifax Stanfield station. The reference station has about 164 frost-free days between those two dates.
Each date is a mean, which makes it the midpoint of a spread and not a safe date. In one year out of two, the last spring frost falls after May 7. In one year out of two, the first fall frost arrives before October 18. Asian greens are cool-season brassicas and tolerate light frost, so a late frost rarely ruins a spring sowing. It does matter for tender seedlings that have not yet hardened off, and it matters for the fall crop, where counting back from a frost date that is only the middle of the range can leave you short.
Here is how the window breaks down by type. Days to maturity count from sowing, since these crops are normally seeded directly in the bed.
| Type | Spring sowing | Late summer and fall sowing |
|---|---|---|
| Mizuna, komatsuna, tatsoi (fast, cold-tolerant leaves) | Mid-April to late May | Early August to early September |
| Baby bok choy and pak choi | Late April to mid-May, before long days arrive | Late July to late August |
| Full-size bok choy | Late April to mid-May, with bolt risk | Late July to mid-August |
| Napa and other heading cabbages | Not recommended | Late July to early August |
| Radish-type and root greens such as daikon | Not recommended | Early to mid-August |
Count backward from October 18 to check the fall dates. A bok choy that needs roughly 45 to 50 days from sowing wants to be in the ground by the end of August at the latest, and earlier if you want full-size heads. Plants also grow slowly once days shorten and nights turn cold, so add two weeks to whatever the seed packet promises. For a closer look at which types suit the season, see The Best Asian Greens for Nova Scotia, and for the wider picture, Growing Asian Greens in Nova Scotia.
What will not work here
The slowest heading types fail in spring. Napa cabbage sown in May meets the longest days of the year around the June solstice at Halifax’s latitude. Long days plus warming weather tell the plant to send up a flower stalk before it forms a head. The result is a tall, bitter plant with no harvest. Napa belongs in the late-summer slot only.
A spring sowing of full-size bok choy is a gamble for the same reason. A cold snap after the seedlings emerge can also push them toward bolting. You can improve the odds with a bolt-resistant variety, a sowing date in late April or early May, and row cover over cold nights. If you want a dependable spring crop, grow it as baby leaf, cut young, before the plant has time to decide to flower.
The fall crop fails when it starts too late. A September sowing of a 50-day bok choy has the autumn frost on its heels, and with the first fall frost arriving before October 18 in half of all years, many plants will still be small when cold nights set in. Light frost sweetens these greens and does little harm, but growth nearly stops as the soil cools. Fast leaves such as mizuna and tatsoi can still make a useful early-September sowing. Heading types and daikon cannot.
Winter is the next limit. The mean daily minimum of the coldest month at the reference station is -10.4 °C (13.3 °F). That is an average of the nightly lows, so individual nights fall below it. Tatsoi and mizuna will sit through hard frosts, but plants left uncovered at that temperature are usually lost. A low tunnel or a cold frame stretches the harvest into early winter. Nothing here should be expected to overwinter in an open bed and resume growth in spring.
Crowding is a smaller trap, but a real one. Heavy, damp air and slow-drying foliage invite slugs and fungal leaf spots. Thin bok choy and mizuna so the leaves dry between showers. In spring, flea beetles pepper brassica seedlings with tiny holes. Floating row cover laid at sowing and tucked in at the edges keeps them off until the plants outgrow the damage.
What changes across Nova Scotia
Halifax is one garden among many. Its Canadian hardiness zone is 6b, per Natural Resources Canada’s 1991-2020 data for the reference city. That is the zone of a single city, and the province does not share it. The Canadian map shows a spread of zones from the milder Atlantic and Fundy shores to cooler inland and upland districts, so there is no single answer for the whole province. The Canadian system also uses seven climate variables where USDA uses one, which means a Canadian zone does not convert to a USDA number.
How should a northern or upland gardener shift the dates?
Northern and upland districts run weeks behind Halifax in spring, and the same districts get their first frost earlier in fall. That squeezes both windows. Push the spring sowing later by a week or two, and pull the late-summer sowing earlier, perhaps to the last days of July for bok choy. Choose the quicker types, and think of the fall crop as the main event. Low tunnels pay for themselves faster in these districts than in the milder parts of the province.
What about the coast?
Gardens near the ocean often run cooler in summer, which helps Asian greens resist bolting. They may also hold off frost a little longer in fall. Those are tendencies, not guarantees, and a sheltered south-facing slope a few miles inland can behave differently. Use the Halifax window as a first pass and adjust it by what your own beds do.
To find your own zone, use the plant hardiness map from Natural Resources Canada and look up your municipality. Don’t assume the Halifax figure applies to you.
Where to check this for your own county
Start with the Nova Scotia Department of Agriculture, the province’s main source for growers. Look there for two things: a planting calendar written for your part of the province, and any list of varieties that have been trialled near you. Those two documents answer the questions a provincewide window can only approximate.
A county recommendation beats a provincial one every time. The window above is built from one weather station and covers the whole province, so it is a starting point. A local calendar reflects the frost dates, soil and growing season of the place you live, and trial results show which varieties actually held up there instead of which ones look good in a catalogue.
When you contact the department, or look through its resources, ask specifically about brassica crops and fall sowings, since Asian greens fall into that family. Ask which pests are active in your district in spring and late summer, and what the local advice is for row cover and timing. A few minutes of reading can save a season of guesswork, especially for the heading types that depend on getting the sowing date right.
Keep in mind that Canadian climate normals cover 1981-2010, while the American figures you may see elsewhere cover 1991-2020. The two sets are not drawn from the same decades, so compare them with care.
Checking this against your own garden
Your own beds outrank every date above. Three observations tell you more than a calendar can.
- Soil warmth by feel. Push your bare hand a few inches into the bed in the morning. If it feels cold and wet enough that you want to pull out, wait. Seeds sown into cold, soggy soil germinate slowly and rot. A bed that warms sooner than your neighbor’s, because of slope or shelter, can be sown a week earlier.
- The first true leaves. After the two seed leaves, the first true leaves show how fast the plants are moving. If seedlings reach that stage, conditions suit them. If it takes much longer, the spot is cooler or shadier than the calendar assumes, and the fall sowing should go in earlier.
- Dandelions and bolting stalks. Dandelions flowering along the roadside is a rough sign that the soil is workable for spring sowing. Later, a thickening center stalk on bok choy means that bed runs warm for the type, and next time you should sow earlier or choose a more bolt-resistant variety.
Write down your sowing dates and what happened. One season of notes on soil warmth, seedling speed and first frost in your own garden gives a better guide than any averaged window, and it is the thing you can adjust from year to year.
Common questions
Can I sow Asian greens before the last spring frost?
Yes, for the hardy leafy types. Mizuna, tatsoi and baby bok choy tolerate light frost, and seeds can go in as soon as the soil can be worked, often under row cover. Since the May 7 mean means the last frost comes later than that date in half of all years, cover young seedlings when a hard frost is forecast.
Is fall or spring better for Asian greens?
Fall is the safer sowing for most types. Spring crops face lengthening days and warming weather, which push bok choy and napa toward bolting. Fall crops mature as days shorten and nights cool, which gives sweeter, more tender leaves. Spring works best for baby leaf harvested young.
How late can I sow bok choy in Nova Scotia?
For full-size plants, aim to finish by the end of August, and earlier in northern or upland districts. Baby bok choy can go in a little later because you cut it small. A mean first fall frost of October 18 means half of all years bring frost sooner, so leave a buffer.
Can Asian greens survive winter in Nova Scotia?
Not in an open bed. The coldest month averages a daily low of -10.4 °C (13.3 °F), and hardy types such as tatsoi need a low tunnel or cold frame to keep producing into early winter. Treat them as annuals, and resow each year.