April is when a cold-zone garden starts to feel real. The snow is mostly gone, the soil is thawing, and on a sunny afternoon a sheltered bed can feel almost warm. It is still too early for tender crops outside — the average last frost is weeks away — but April is the first month when hardy crops can go into the ground, and the last big wave of indoor sowing happens now.
What makes April different from March is the soil.
Zone 1 in April: the frost window
Zone 1 is the coldest USDA zone in this guide, with winter lows below -50°F. The average last spring frost falls around June 15 and the average first autumn frost falls around August 1, which leaves roughly six to seven weeks between the average last spring frost and the average first autumn frost. Everything here runs on the latest timetable in the United States: sow tender crops indoors late, transplant only after mid-June, and harvest fast. Those dates are USDA zone averages from the USDA Plant Hardiness Zone Map and NOAA frost records — they are ranges, not exact dates for any one garden, and they vary by microclimate, elevation and year, so check your local extension service before you plant tender crops outside. Our harvest date calculator gives you the averages for your zone, and the planting calendar hub lists every zone and month.
Your April task list
- Direct-sow peas, spinach, lettuce, radishes, carrots and beets as the soil becomes workable.
- Plant onion sets and seed potatoes.
- Harden off and transplant brassicas, onions and leeks; protect with row cover on frosty nights.
- Start cucumbers, zucchini and corn indoors late in the month.
- Keep indoor tomatoes and peppers under strong light and pot them on before they get root-bound.
- Weed early — small weeds pulled now are far easier than established ones in June.
What to start indoors in April
- Cucumbers and zucchini (late April) — Both germinate in 7–10 days and grow fast, so start them late in the month, only a few weeks before transplanting. Started too early they become root-bound and sulky.
- Sweet corn (late April, under cover) — Corn takes 60–90 days and is tender, so it is started indoors only in the last part of April, for transplanting after frost.
- Basil and other tender herbs — Basil takes 60–70 days and is tender. A late-April indoor sowing gives it time to grow while it waits for warm weather.
- Succession tomatoes and peppers — If your March sowing failed or was thin, April is the last sensible moment for a replacement sowing — any later and plants will be too small for a short season.
Give seedlings strong light close above them, keep the soil moist but not soggy, and label every tray with the crop and sowing date.
What to direct-sow outdoors in April
April is the first direct-sowing month: peas (60–70 days, hardy), spinach (40–50 days, hardy), lettuce (45–60 days, hardy), radishes (25–40 days, hardy — the fastest crop you will grow), carrots (60–80 days, hardy, germinating slowly in 14–21 days), and beets (50–70 days). Sow radishes and lettuce in small batches every couple of weeks so they do not all mature at once. Plant onion sets and seed potatoes once the soil is workable; potatoes take 70–120 days, so April planting is what makes an autumn harvest possible.
What to transplant and harvest in April
Hardy transplants can start going out in April as the soil warms: onion and leek seedlings, and brassicas such as broccoli and cabbage, which are frost-tolerant and prefer cool weather. Harden them off first — a few hours outside in shelter each day, building up over a week — and cover them with row cover if a hard frost is forecast. Tender transplants stay indoors.
The first harvests are still weeks away, but April is when you can start cutting the earliest microgreens and the first indoor herbs. Outdoors, overwintered herbs such as chives and mint (in pots) begin to regrow, and you can snip the first leaves. The real harvest starts in late spring, from the peas and salads sown now.
Frost protection in April
April frost is the frost that matters most: a late freeze can kill a tender transplant and set back hardy seedlings. Row cover, cloches and cold frames are worth using nightly on anything newly planted, and a bucket or fleece over a single plant is better than nothing. Always check the forecast, and remember your frost dates are zone averages — check your local extension service for the dates that apply to your area.
April planting data — Zone 1
| Crop | Germination | Days to maturity | Spacing | Soil pH | Cold tolerance |
|---|---|---|---|---|---|
| Peas | 7–14 days | 60–70 days | 2–3 in | 6.0–7.5 | hardy |
| Spinach | 7–14 days | 40–50 days | 4–6 in | 6.0–7.5 | hardy |
| Radishes | 4–7 days | 25–40 days | 2–3 in | 6.0–7.0 | hardy |
| Carrots | 14–21 days | 60–80 days | 2–3 in | 6.0–6.8 | hardy |
| Potatoes | 14–28 days | 70–120 days | 12 in | 5.0–6.0 | frost-tolerant |
Frequently asked questions
What can I plant outside in April?
Hardy crops: peas, spinach, lettuce, radishes, carrots and beets can be direct-sown once the soil is workable, and onion sets and seed potatoes can go in. Tender crops such as tomatoes, beans and squash must stay indoors until after the average last frost.
When can I transplant broccoli and cabbage outside?
Broccoli and cabbage are frost-tolerant, so they can go out in April once hardened off, with row cover on frosty nights. They prefer cool weather and will bolt if transplanted too late into summer heat.
How do I harden off seedlings?
Put them outside in shelter for a few hours a day, building up over about a week, and bring them in at night. Start in shade and still air, then give them more sun and wind.
When is the last frost in my zone?
In Zone 1, the average last spring frost falls around June 15 and the average first autumn frost falls around August 1. Frost dates here are zone averages, not exact dates for any one place, and they vary by microclimate, elevation and year — check your local extension service before planting tender crops outside.
April is the month the garden moves outside for the first time: hardy seeds in the ground, brassicas hardening off, and potatoes in. Tender crops still wait — but the season has genuinely begun. Browse the planting calendar hub for every month in your zone, see last month, or look ahead to next month, and see how the same month looks in a milder zone in the Zone 7 January guide.