What to plant in March in Iowa
In Iowa (IA), March sits about 6 weeks before the average last frost (April 25). The state averages 166 frost-free days a year (last frost April 25, first frost October 8; USDA zones 4b, 5a, 5b).
65 crops have a sowing or planting window this month, including mache (corn salad), pea, spinach, green onion / scallion, arugula, beet - and 16 of those windows close during March.
Dates here come from Iowa frost dates (last frost Apr 25, first frost Oct 8). For one crop in detail, see when to plant pea, spinach or arugula in Iowa.
Iowa: planting activity through the year
Last chance in March
Bell Pepper (start seeds indoors, by Mar 7) · Chili Pepper (start seeds indoors, by Mar 7) · Ginger (start seeds indoors, by Mar 7) · Green Onion / Scallion (start seeds indoors, by Mar 7) · Mint (start seeds indoors, by Mar 7) · Oregano (start seeds indoors, by Mar 7) · Sage (start seeds indoors, by Mar 7) · Tarragon (start seeds indoors, by Mar 7) · Thyme (start seeds indoors, by Mar 7) · Turmeric (start seeds indoors, by Mar 7) · Ground Cherry (start seeds indoors, by Mar 14) · Lemon Balm (start seeds indoors, by Mar 14) · Shiso (Perilla) (start seeds indoors, by Mar 14) · Sweet Marjoram (start seeds indoors, by Mar 14) · Tomatillo (start seeds indoors, by Mar 14) · Tomato (start seeds indoors, by Mar 14)
Sow or plant outdoors in March (30)
Direct sowing and transplanting windows that fall in March, most urgent first. Windows are one-to-two-week bands around the ideal date.
| Crop | What to do | Window | This month |
|---|---|---|---|
| Mache (Corn Salad) | Direct sow (spring) | Mar 16 – Apr 4 | Opens Mar 16 |
| Pea | Direct sow (spring) | Mar 16 – Apr 4 | Opens Mar 16 |
| Spinach | Direct sow (spring) | Mar 16 – Apr 4 | Opens Mar 16 |
| Green Onion / Scallion | Transplant outdoors | Mar 21 – Apr 7 | Opens Mar 21 |
| Arugula | Direct sow (spring) | Mar 23 – Apr 11 | Opens Mar 23 |
| Beet | Direct sow (spring) | Mar 23 – Apr 11 | Opens Mar 23 |
| Fava Bean (Broad Bean) | Direct sow (spring) | Mar 23 – Apr 11 | Opens Mar 23 |
| Green Onion / Scallion | Direct sow (spring) | Mar 23 – Apr 11 | Opens Mar 23 |
| Mizuna | Direct sow (spring) | Mar 23 – Apr 11 | Opens Mar 23 |
| Onion | Direct sow (spring) | Mar 23 – Apr 11 | Opens Mar 23 |
| Radish | Direct sow (spring) | Mar 23 – Apr 11 | Opens Mar 23 |
| Shallot | Direct sow (spring) | Mar 23 – Apr 11 | Opens Mar 23 |
| Tatsoi | Direct sow (spring) | Mar 23 – Apr 11 | Opens Mar 23 |
| Cabbage | Transplant outdoors | Mar 28 – Apr 14 | Opens Mar 28 |
| Collard Greens | Transplant outdoors | Mar 28 – Apr 14 | Opens Mar 28 |
| Horseradish | Plant crowns / divisions | Mar 28 – Apr 14 | Opens Mar 28 |
| Kale | Transplant outdoors | Mar 28 – Apr 14 | Opens Mar 28 |
| Kohlrabi | Transplant outdoors | Mar 28 – Apr 14 | Opens Mar 28 |
| Onion | Transplant outdoors | Mar 28 – Apr 14 | Opens Mar 28 |
| Rhubarb | Plant crowns / divisions | Mar 28 – Apr 14 | Opens Mar 28 |
| Shallot | Transplant outdoors | Mar 28 – Apr 14 | Opens Mar 28 |
| Carrot | Direct sow (spring) | Mar 30 – Apr 18 | Opens Mar 30 |
| Chervil | Direct sow (spring) | Mar 30 – Apr 18 | Opens Mar 30 |
| Endive & Escarole | Direct sow (spring) | Mar 30 – Apr 18 | Opens Mar 30 |
| Kohlrabi | Direct sow (spring) | Mar 30 – Apr 18 | Opens Mar 30 |
| Lettuce | Direct sow (spring) | Mar 30 – Apr 18 | Opens Mar 30 |
| Mustard Greens | Direct sow (spring) | Mar 30 – Apr 18 | Opens Mar 30 |
| Rapini (Broccoli Raab) | Direct sow (spring) | Mar 30 – Apr 18 | Opens Mar 30 |
| Turnip | Direct sow (spring) | Mar 30 – Apr 18 | Opens Mar 30 |
| Watercress | Direct sow (spring) | Mar 30 – Apr 18 | Opens Mar 30 |
Start seeds indoors in March (47)
Indoor sowings for transplants later. Six to eight weeks under lights is typical for tomatoes and peppers; onions and leeks need longer.
| Crop | What to do | Window | This month |
|---|---|---|---|
| Bell Pepper | Start seeds indoors | Feb 21 – Mar 7 | Last chance - ends Mar 7 |
| Chili Pepper | Start seeds indoors | Feb 21 – Mar 7 | Last chance - ends Mar 7 |
| Ginger | Start seeds indoors | Feb 21 – Mar 7 | Last chance - ends Mar 7 |
| Green Onion / Scallion | Start seeds indoors | Feb 21 – Mar 7 | Last chance - ends Mar 7 |
| Mint | Start seeds indoors | Feb 21 – Mar 7 | Last chance - ends Mar 7 |
| Oregano | Start seeds indoors | Feb 21 – Mar 7 | Last chance - ends Mar 7 |
| Sage | Start seeds indoors | Feb 21 – Mar 7 | Last chance - ends Mar 7 |
| Tarragon | Start seeds indoors | Feb 21 – Mar 7 | Last chance - ends Mar 7 |
| Thyme | Start seeds indoors | Feb 21 – Mar 7 | Last chance - ends Mar 7 |
| Turmeric | Start seeds indoors | Feb 21 – Mar 7 | Last chance - ends Mar 7 |
| Ground Cherry | Start seeds indoors | Feb 28 – Mar 14 | Last chance - ends Mar 14 |
| Lemon Balm | Start seeds indoors | Feb 28 – Mar 14 | Last chance - ends Mar 14 |
| Shiso (Perilla) | Start seeds indoors | Feb 28 – Mar 14 | Last chance - ends Mar 14 |
| Sweet Marjoram | Start seeds indoors | Feb 28 – Mar 14 | Last chance - ends Mar 14 |
| Tomatillo | Start seeds indoors | Feb 28 – Mar 14 | Last chance - ends Mar 14 |
| Tomato | Start seeds indoors | Feb 28 – Mar 14 | Last chance - ends Mar 14 |
| Broccoli | Start seeds indoors | Mar 7 – Mar 21 | Mar 7 – Mar 21 |
| Brussels Sprouts | Start seeds indoors | Mar 7 – Mar 21 | Mar 7 – Mar 21 |
| Cabbage | Start seeds indoors | Mar 7 – Mar 21 | Mar 7 – Mar 21 |
| Cauliflower | Start seeds indoors | Mar 7 – Mar 21 | Mar 7 – Mar 21 |
| Kale | Start seeds indoors | Mar 7 – Mar 21 | Mar 7 – Mar 21 |
| Basil | Start seeds indoors | Mar 14 – Mar 28 | Mar 14 – Mar 28 |
| Collard Greens | Start seeds indoors | Mar 14 – Mar 28 | Mar 14 – Mar 28 |
| Endive & Escarole | Start seeds indoors | Mar 14 – Mar 28 | Mar 14 – Mar 28 |
| Kohlrabi | Start seeds indoors | Mar 14 – Mar 28 | Mar 14 – Mar 28 |
| Malabar Spinach | Start seeds indoors | Mar 14 – Mar 28 | Mar 14 – Mar 28 |
| Okra | Start seeds indoors | Mar 14 – Mar 28 | Mar 14 – Mar 28 |
| Radicchio | Start seeds indoors | Mar 14 – Mar 28 | Mar 14 – Mar 28 |
| Summer Savory | Start seeds indoors | Mar 14 – Mar 28 | Mar 14 – Mar 28 |
| Bitter Melon | Start seeds indoors | Mar 21 – Apr 4 | Opens Mar 21 |
| Bok Choy / Pak Choi | Start seeds indoors | Mar 21 – Apr 4 | Opens Mar 21 |
| Cucamelon | Start seeds indoors | Mar 21 – Apr 4 | Opens Mar 21 |
| Fennel (Bulb) | Start seeds indoors | Mar 21 – Apr 4 | Opens Mar 21 |
| Lettuce | Start seeds indoors | Mar 21 – Apr 4 | Opens Mar 21 |
| Luffa (Loofah Gourd) | Start seeds indoors | Mar 21 – Apr 4 | Opens Mar 21 |
| Napa Cabbage | Start seeds indoors | Mar 21 – Apr 4 | Opens Mar 21 |
| New Zealand Spinach | Start seeds indoors | Mar 21 – Apr 4 | Opens Mar 21 |
| Peanut | Start seeds indoors | Mar 21 – Apr 4 | Opens Mar 21 |
| Swiss Chard | Start seeds indoors | Mar 21 – Apr 4 | Opens Mar 21 |
| Watercress | Start seeds indoors | Mar 21 – Apr 4 | Opens Mar 21 |
| Cantaloupe / Muskmelon | Start seeds indoors | Mar 28 – Apr 11 | Opens Mar 28 |
| Cucumber | Start seeds indoors | Mar 28 – Apr 11 | Opens Mar 28 |
| Pumpkin | Start seeds indoors | Mar 28 – Apr 11 | Opens Mar 28 |
| Sunflower | Start seeds indoors | Mar 28 – Apr 11 | Opens Mar 28 |
| Watermelon | Start seeds indoors | Mar 28 – Apr 11 | Opens Mar 28 |
| Winter Squash | Start seeds indoors | Mar 28 – Apr 11 | Opens Mar 28 |
| Zucchini / Summer Squash | Start seeds indoors | Mar 28 – Apr 11 | Opens Mar 28 |
Planting dates for popular crops in Iowa
Every crop has its own full-year dates for Iowa: indoor start, transplant or direct sowing, and harvest.
Seed-starting season: March garden jobs in Iowa
- Start 47 crops indoors this month, including bell pepper, chili pepper, ginger, green onion / scallion. Use a sterile mix and good light - see starting seeds indoors.
- 6 weeks until the average last frost (April 25). The seed-starting calculator works out each crop's exact sowing date from it.
- Keep seedlings from stretching: lights 2-3 inches above the leaves for 14-16 hours a day, and a fan or a daily brush of the hand across the tops.
- Prepare beds as soon as the soil crumbles instead of smearing when squeezed - working wet soil ruins its structure for the season.
USDA zone chart for Iowa
Iowa spans USDA zones 4b, 5a, 5b. Colder zones, usually higher or further inland, have a later last spring frost and an earlier first fall frost than the state average.
Questions gardeners ask
What vegetables can I plant in Iowa in March?
65 crops have a window in March: mache (corn salad), pea, spinach, green onion / scallion, arugula, beet, fava bean (broad bean), mizuna, onion, radish and more. The tables above give the exact dates for each.
Is it too late to plant tomatoes in Iowa in March?
No - start seeds indoors runs Feb 28 – Mar 14 in Iowa, so do it before March 14.
Is it too late to plant lettuce in Iowa in March?
No - start seeds indoors runs Mar 21 – Apr 4 in Iowa.
When is the first frost in Iowa?
The statewide average first fall frost is around October 8 and the last spring frost around April 25. Your town can be a week or two either side - look yours up by ZIP code.
What should I start indoors in March in Iowa?
Bell Pepper (Feb 21 – Mar 7), Chili Pepper (Feb 21 – Mar 7), Ginger (Feb 21 – Mar 7), Green Onion / Scallion (Feb 21 – Mar 7), Mint (Feb 21 – Mar 7), Oregano (Feb 21 – Mar 7), Sage (Feb 21 – Mar 7), Tarragon (Feb 21 – Mar 7), Thyme (Feb 21 – Mar 7), Turmeric (Feb 21 – Mar 7), Ground Cherry (Feb 28 – Mar 14), Lemon Balm (Feb 28 – Mar 14), Shiso (Perilla) (Feb 28 – Mar 14), Sweet Marjoram (Feb 28 – Mar 14), Tomatillo (Feb 28 – Mar 14), Tomato (Feb 28 – Mar 14), Broccoli (Mar 7 – Mar 21), Brussels Sprouts (Mar 7 – Mar 21), Cabbage (Mar 7 – Mar 21), Cauliflower (Mar 7 – Mar 21), Kale (Mar 7 – Mar 21), Basil (Mar 14 – Mar 28), Collard Greens (Mar 14 – Mar 28), Endive & Escarole (Mar 14 – Mar 28), Kohlrabi (Mar 14 – Mar 28), Malabar Spinach (Mar 14 – Mar 28), Okra (Mar 14 – Mar 28), Radicchio (Mar 14 – Mar 28), Summer Savory (Mar 14 – Mar 28), Bitter Melon (Mar 21 – Apr 4), Bok Choy / Pak Choi (Mar 21 – Apr 4), Cucamelon (Mar 21 – Apr 4), Fennel (Bulb) (Mar 21 – Apr 4), Lettuce (Mar 21 – Apr 4), Luffa (Loofah Gourd) (Mar 21 – Apr 4), Napa Cabbage (Mar 21 – Apr 4), New Zealand Spinach (Mar 21 – Apr 4), Peanut (Mar 21 – Apr 4), Swiss Chard (Mar 21 – Apr 4), Watercress (Mar 21 – Apr 4), Cantaloupe / Muskmelon (Mar 28 – Apr 11), Cucumber (Mar 28 – Apr 11), Pumpkin (Mar 28 – Apr 11), Sunflower (Mar 28 – Apr 11), Watermelon (Mar 28 – Apr 11), Winter Squash (Mar 28 – Apr 11), Zucchini / Summer Squash (Mar 28 – Apr 11).
What to plant in March in other states
Dates are computed from Iowa’s statewide average frost dates (from NOAA/NCEI climate normals) and each crop’s timing in our crop database. Your garden may be a week or two either side - for dates tuned to your ZIP code, use the planting calendar.