In Arkansas, indoor seed starting runs from late November for onions and leeks to late February for tomatoes. Every date counts back from a last spring frost of March 12 to March 28 at Little Rock. Peppers and eggplant go in January 8 to January 24, and tomatoes January 29 to February 21. The colder northern part of the state sows later and the milder south a little earlier. The calendar below gives each crop its own window.
The date everything counts back from
Indoor sowing dates are worked backward. Take the last spring frost, subtract the number of weeks a seedling needs to reach transplant size, and you have the sowing date. The frost date for Little Rock comes from the NOAA NCEI 1991-2020 Climate Normals: the 32°F freeze probabilities fall in the 30 to 70 percent band between March 12 and March 28. Inside that stretch, one more freeze goes from likely to unlikely. Nobody can say which day the last one will land on, so a range is the honest number. The First and Last Frost Dates in Arkansas page covers how those dates are built.
The range changes how you plan. Count back from the early end, March 12, and seedlings may sit in their pots for a week or two while a late cold snap holds them indoors. They stretch, crowd their roots and arrive at the garden tired. Count back from the late end, March 28, and a warm spring means you could have been planting weeks sooner. The sowing windows in this calendar cover both ends so you can pick the part that fits your setup. With a bright light and extra pots, lean early. With only a window, lean late.
Which frost date should tender crops use?
Tomatoes, peppers, eggplant, okra and sweet potatoes are damaged well above freezing. At the 36°F light-frost threshold, NWS Little Rock gives April 3 for the last spring date and October 31 for the first fall date. Tender plants need those dates, not the 32°F ones. For these crops, the later half of each sowing window is usually the safer pick, because the plants will not be outdoors until April anyway.
The reference point here is Little Rock, and the rest of the state differs. The USDA Plant Hardiness Zone Map (2023, built on 1991-2020 normals) places Arkansas in zones 7a to 8b. That system rests on one variable, the average annual extreme minimum temperature, so it says little about when the last frost arrives. What matters for timing is direction. The Ozarks and other higher, northern ground see their last frost later, so every sowing date there moves later. The southern and Delta counties are milder and can start earlier. Your county extension office can tell you how far your ZIP code sits from Little Rock, and the Arkansas guides collect more local timing.
Write down March 12 to March 28 as the last-frost range, then count back from it.
The calendar, crop by crop
The weeks below are the usual extension guidance from University of Minnesota Extension, which lists how long each crop typically stays indoors before planting out. They are general horticultural practice and not a law, since a cool room or a weak light adds time. The sowing windows count those weeks back from March 12 to March 28, except sweet potatoes, which are timed from a later planting-out date.
| Crop | Usual weeks indoors | Sow indoors in Arkansas (Little Rock) |
|---|---|---|
| Leeks, onions | 14-15 weeks | November 27 to December 20 |
| Celery | 12-13 weeks | December 11 to January 3 |
| Broccoli, Brussels sprouts, cabbage, cauliflower, head lettuce | 10-11 weeks | December 25 to January 17 |
| Eggplant, okra, peppers | 9 weeks | January 8 to January 24 |
| Tomatoes | 5-6 weeks | January 29 to February 21 |
| Sweet potatoes (grown from slips, not seed) | About 6-8 weeks to grow slips (not from the Minnesota table) | Start slips 6-8 weeks before a planting-out date in April or later |
Read the table as a sequence. Onions and leeks go first, in the weeks around Thanksgiving and early December, and they need the longest wait. The cabbage family and head lettuce follow after the holidays. Peppers and eggplant come in the second half of January, and tomatoes close out winter. Tomatoes need only 5-6 weeks indoors, so starting them too early can produce plants that have outgrown their pots by planting time. The Growing Tomato Seedlings Indoors page covers the pot-up steps, and Starting Lettuce covers head and leaf types.
A few notes on specific rows. Onions and leeks at 14 to 15 weeks are the hardest to manage from seed on a windowsill, and buying transplants is a common shortcut. Peppers and eggplant germinate slowly and want the most warmth, so the nine weeks include a slow start. Okra is listed with them in the extension table, though it can also be sown straight into warm garden soil. Sweet potatoes are not grown from seed: gardeners root slips from a stored tuber, usually 6 to 8 weeks before planting out, and the slips go out only after the soil has warmed well past frost season.
Which crops should not be started indoors?
Root crops such as carrots, beets, radishes, turnips and parsnips resent being moved. Their taproots fork or stunt when disturbed, so they belong in the ground from the start. Beans, peas and sweet corn germinate readily when sown in the garden and gain little from a head start in a pot. Squash, cucumbers and melons are the one group where gardeners sometimes start early, but in most cases they grow so quickly that a seedling kept indoors becomes root-bound before the soil is ready for it. If you do try them, start them late in the window for tender plants and keep the pots large.
Once you have your dates, set them against the Arkansas Planting Calendar so the indoor starts line up with what can go straight into the ground in the same weeks.
Mark peppers and eggplant for January 8 to January 24 and tomatoes for January 29 to February 21.
Light, warmth and hardening off
Winter sun in Arkansas is low, short and often filtered by cloud, and a windowsill collects only a fraction of what a seedling needs. The plant responds by stretching toward the glass. Stems turn long, thin and pale, and the plant leans. These leggy seedlings can recover only partly, and they flop easily once they meet wind outdoors. A basic shop light or full-spectrum fixture hung close to the tops of the seedlings fixes this. Raise it as the plants grow, and run it on a timer so the days are consistent.
Warmth matters just as much, and in a different way. Seeds germinate on steady warmth, and a cold drafty room is a common reason a tray of peppers takes weeks to show. Pepper, eggplant and tomato seeds like a warmer spot than cabbage-family seeds, which sprout in cooler rooms. A heat mat under the tray gives steady bottom warmth. Once seedlings emerge, move them to a brighter and slightly cooler spot. Cooler air after germination keeps growth stocky.
How do you harden off seedlings?
Hardening off is a step that is often skipped. University of Minnesota Extension advises hardening off all plants over the last 1 to 2 weeks before planting out. Indoor seedlings have never felt direct sun, wind or a night chill, so the shock of moving straight to the garden can scorch leaves or stop growth.
Start by setting the trays outdoors in shade, out of the wind, for a couple of hours. Each day, lengthen the time and add some direct sun. By the end of the week or two they should stay out all day and, if nights are mild, overnight. Bring them in whenever the forecast shows a night near frost. Cool-season crops like broccoli and cabbage can go out earlier and take the chill. Tender crops wait for the April 3 light-frost date at 36°F and for warmer nights.
Begin hardening off 1 to 2 weeks before your planting-out date, and treat a cold night as a reason to bring trays back in.
What goes wrong
Starting too early is a common error. Seedlings sown weeks ahead of the window outgrow their cells, with roots circling the bottom, lower leaves yellowing and sometimes flower buds forming on a plant that is only a few inches tall. Once that happens, the plant often sets less fruit after transplanting. The fix is prevention, so follow the windows above. If seedlings get ahead anyway, pot them up into larger containers and keep them cool and bright.
Damping off is a fungal problem that hits young seedlings. The stem pinches at the soil line, turns thin and dark, and the seedling falls over, often in a patch that spreads across a tray. It thrives in soggy, stagnant conditions. Clean containers, fresh seed-starting mix, light and even watering from the bottom, and a small fan for air movement are the usual defenses. A thin dusting of dry material over the surface can help the top layer stay dry. Once a seedling has collapsed it cannot be saved, so remove it and let the tray dry.
Planting out too early is the third trouble. The average last frost of March 12 to March 28 is a 32°F figure, and soil at that time is still cold. A tomato or pepper set out the week after that average often stops growing, and its leaves can turn purple from cold roots. If a late frost comes, it can kill the plant outright. Tender crops can go out around the 36°F light-frost date of April 3 (a 50 percent date, so a later frost is still possible) once nights have warmed, and a row cover on cool nights adds a margin.
Hold tender transplants indoors until after April 3, and cover them on any night the forecast dips near frost.
Common questions
Can I start tomato seeds in January in Arkansas?
Only at the very end of the month: seeds sown before January 29 will usually give plants too big by planting time. The tomato window for Little Rock is January 29 to February 21, based on 5 to 6 weeks indoors. Seeds sown earlier will be tall and root-bound by the time April nights are warm enough.
Does northern Arkansas start seeds later than Little Rock?
Yes. Higher and more northern ground has a later last spring frost, so every sowing date shifts later there. The milder south and Delta areas can start a bit earlier than the Little Rock windows. Your county extension office can tell you how to adjust for your location.
When do I start head lettuce seeds indoors?
The extension guidance of 10 to 11 weeks indoors puts head lettuce at December 25 to January 17 in Arkansas, counted back from the Little Rock frost range. Lettuce is also commonly sown straight into cool garden soil, and the Starting Lettuce page lays out both routes.
What if I miss my sowing window?
Sow as soon as you can and accept a smaller plant at transplant time, or buy transplants for the slowest crops like onions and leeks. A seedling that is a few weeks younger than the guidance usually catches up once it is in warm soil. Check the Arkansas Planting Calendar to see whether a direct sowing fits your timing better.
Sources: ncei.noaa.gov | extension.umn.edu