Plant fast, cool-season types: baby bok choy, tatsoi, mizuna, komatsuna and leaf mustards. They finish before Indiana’s summer heat or start after it breaks. Slow heading types like napa cabbage are riskier, and heat-lovers like amaranth and water spinach are summer fillers. The state’s frost dates and cold winters explain this sorting.
The short answer for Indiana
The frost dates set the rhythm. At the Indianapolis reference station, NOAA’s 1991-2020 Climate Normals put the last spring frost at April 9 to April 21. That range is a probability of a 32F freeze, the 30-70% band, not a guarantee. The first fall frost falls at October 21 to October 30, measured the same way. Everything between those windows is the warm season, and most Asian greens do their best work on either side of it.
Match the type to the window
Leafy types that grow quickly suit this calendar best. They can be sown as soon as the soil is workable in spring, harvested young, and sown again in late summer for fall. Heading types need a longer, cooler stretch, which in Indiana means a fall crop.
| Type | Best window | Why it fits |
|---|---|---|
| Baby bok choy, tatsoi, mizuna, komatsuna | Early spring and late summer into fall | Quick to harvest, so they beat both the heat and the freeze |
| Leaf mustards | Spring and fall | Handle cool weather well, turn sharp and bolt in heat |
| Napa cabbage and full-size heading types | Fall main crop | Need a long cool finish, which the late October frost window allows |
| Amaranth greens, water spinach | After frost danger, through summer | Heat-lovers that fill the gap cool-season crops leave |
Why fall wins
Fall is the better season for most of these crops. Seedlings sown in late summer mature as days shorten and nights cool, which holds off bolting. Spring crops race against rising heat. For exact sowing dates, see When to Sow Asian Greens in Indiana. For the broader picture, start with Growing Asian Greens in Indiana.
What will not work here
Three things fail in Indiana, and the numbers explain each.
First, spring planting on the early edge of the range. April 9 is when the freeze probability sits at the low end of the band, not when frost is over. Purdue notes roughly a 10% chance of a 32F event even after the published spring date. Tender seedlings set out early without a row cover handy are a bet, and a cheap one to lose if you have fabric ready, an expensive one if you don’t.
Second, any long-season heading crop started late. The window between sowing and the October 21 to October 30 frost range is finite. A napa cabbage sown in spring will meet summer heat while it is trying to form a head, and it tends to bolt instead. Sowed too late in summer, it runs out of days before the freeze band arrives. Heading types leave the least room for error.
Third, expecting these greens to overwinter outdoors. The mean daily minimum of the coldest month is 20.9F at Indianapolis. That is an average low, not the record, so actual nights dip below it. Most Asian greens stop growing well before January and many will not survive an unprotected winter. Some tolerate light frost and even sweeten with it, but a hard freeze ends the crop. Treat them as annuals with a fall deadline, and consider a low tunnel to stretch the season rather than to carry plants through winter.
Summer is the fourth problem, though this page carries no summer temperature or rainfall figure for Indiana, so it cannot give you a number. What can be said without one: warm, humid stretches punish tight spacing, because leaves stay wet and disease moves quickly through a crowded bed. Spacing leafy crops generously and watering at the soil rather than overhead is a safer default here than packing rows as you might in a dry climate.
What changes across Indiana
Indiana is not one garden. The USDA Plant Hardiness Zone Map (2023, built on 1991-2020 normals) lists the state at 5b to 7a. That is a span of several zones, so there is no single answer for the whole state. The map is built on one variable, the average annual extreme minimum temperature, which tells you about winter survival. It says little about how long your growing season runs for a fast crop.
The frost dates above use Indianapolis as the reference point. Southern Indiana runs earlier in spring and later in autumn than the north by a fortnight or more. A gardener near the Ohio River can start spring sowings sooner and keep fall crops going longer, and may find that a heading type that is a gamble farther north is a reasonable fall crop there.
In northern Indiana, shift the other way. Start spring sowings later than the Indianapolis range suggests, and sow fall crops earlier, since the first fall freeze arrives sooner. Heading types lose the most room. Favor quick leafy types and treat napa as an experiment, with row cover ready on both ends of the season.
Do not take a zone from this page. Look up your own on the USDA Plant Hardiness Zone Map by ZIP code, and remember that a zone describes winter cold, not the frost dates that govern these crops.
Where to check this for your own county
A county recommendation beats a state one, and this page is the state one. Your county’s soil, elevation and nearest weather station can move the dates by days or weeks.
Start with Purdue Extension, the land-grant extension service for Indiana. Contact your county office through the site and look for two things.
- The local planting calendar, with spring and fall dates tied to your county rather than to Indianapolis.
- Varieties trialled nearby, meaning cultivars that have been grown and evaluated in Indiana conditions, ideally with notes on bolting and disease.
Extension offices in other states publish calendars by crop, and the format varies. The information this page has found for lawn care, for example, is organized by species, not by state, so a cool-season calendar and a warm-season one are worked in opposite halves of the year. Apply the same logic here and look for the calendar covering leafy cool-season vegetables, not one for tomatoes or lawns.
This page does not have a county-level Asian greens calendar for Indiana, and it will not pretend to. If the extension office gives you dates that differ from those here, use theirs.
Checking this against your own garden
Your own observations outrank every date on this page. Three are worth watching, none needing equipment.
Soil warmth by feel. In early spring, dig a handful from the bed. If it is workable, crumbles rather than clumps, and no longer feels sharply cold in your palm, cool-season seed will germinate. A bed that stays cold and wet long after a neighbor’s is telling you about drainage and shade, and your first sowing should wait.
The first flush of male flowers. Many gardeners use tree and shrub blooms as a local clock. When early-blooming trees open in your yard, you are seeing the real arrival of spring where you live, which may run ahead of or behind the Indianapolis range. If a patch of ground blooms earlier than the rest, it is warmer, and that is where an early sowing belongs.
The first true leaves. Seedlings first show seed leaves, then the true leaves. If true leaves appear quickly, the bed is warm enough to keep going. If they stall, or if plants bolt almost as soon as they leaf out, the sowing date was off for that spot. Write the date down. Next year’s calendar is built from this year’s notes.
Common questions
What is the single best Asian green for Indiana?
No single type wins, but quick-growing leafy greens like baby bok choy, tatsoi and mizuna are the most forgiving. They tolerate cool weather and can be harvested young, before heat or a hard freeze arrives.
Can I grow napa cabbage in Indiana?
Yes, as a fall crop. It needs a long cool finish, so timing matters. In northern Indiana, where the first fall freeze comes sooner, it is a bigger gamble than in the south.
When is the last spring frost in Indiana?
At the Indianapolis reference station, the range is April 9 to April 21, based on 32F freeze probabilities in the 30-70% band (NOAA 1991-2020). Purdue notes roughly a 10% chance of a 32F event after the published date, and southern Indiana runs earlier than the north.
Will Asian greens survive an Indiana winter?
Generally not unprotected. The mean daily minimum of the coldest month is 20.9F at Indianapolis, and the real lows go lower. Plan on fall harvests, and use covers only to stretch the season.