February garden tasks: Midwest

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Indoor seed starting by zone

February is when the seed-starting calendar from January goes into action. Following the zone dates in the March guide:

• Zone 6 (St. Louis, Kansas City, Indianapolis, Columbus; last frost around April 7–15): onions and leeks in early February if not started in January, then peppers and eggplant in mid-to-late February. Tomatoes go in from late February to early March.
• Zone 5 (Chicago, Milwaukee, Des Moines, Detroit; last frost late April to early May): onions and leeks in early-to-mid February. Peppers and eggplant February 20–28. Tomatoes wait until March 7–14.
• Zone 4 (Minneapolis–St. Paul, northern WI and MI; last frost around May 7): onions and leeks in late February. Peppers and eggplant wait until early March.

Iowa State Extension places indoor onion sowing for Iowa in February. Sow thickly in flats and trim the tops back to about 3 inches whenever they flop over, which gives stockier transplants. Per Illinois Extension, check each seed packet for its weeks-to-transplant and count back from your frost date rather than sowing everything at once.

Setup reminders: germinate peppers and eggplant warm (70–80°F soil) and grow seedlings under lights 2–3 inches above the leaves for 14–16 hours a day. Once seedlings emerge, keep the room cooler, around 60–65°F, so they stay stocky. See starting seeds indoors.

Cool-season transplants and spring orders

Broccoli, cabbage, cauliflower, kohlrabi and lettuce for transplanting need about 4–6 weeks indoors. They go outside a few weeks before the last frost, because light frost does not hurt them.

• Zone 6: sow them indoors in mid-to-late February for transplanting in late March or early April, when the March guide's cool-season window opens.
• Zones 4–5: sow them in March for April or early-May planting.
• Order seed potatoes, onion sets and plants, asparagus crowns and bare-root fruit now if you have not already. Plant potatoes once the soil reaches about 45°F.
• Harden off every transplant over 7–10 days before it goes outside. See hardening off seedlings.

Late-winter pruning: trees and shrubs

Purdue Consumer Horticulture recommends late winter for most pruning. Branch structure is easy to see, the hardest cold is usually over, and wounds start to close as soon as growth begins. Zone 6 gardeners can start in February. In zones 4–5, February thaws are a head start on work that continues through March.

Prune now:

• Deciduous shade trees: remove dead, crossing and rubbing branches and competing leaders. Maples, birches and walnuts bleed sap from late-winter cuts. Per Iowa State Extension, the bleeding is not harmful.
• Summer-blooming shrubs on new wood: panicle and smooth hydrangeas, potentilla, summer spirea and Japanese spirea. See pruning hydrangeas by type.
• Oaks: finish before April. Per UMN Extension, oaks should not be pruned from April through July because of oak wilt.

Do not prune: lilac, forsythia, spring-blooming spirea, azalea or bigleaf hydrangea. Per Iowa State Extension, these bloom on last year's wood and should be pruned right after flowering.

Fruit trees, grapes and raspberries

Per UMN Extension, apples should be pruned in late winter while dormant, before bud swell. In zones 4–5 that is mostly March, as the March guide notes. In zone 6, late February works on mild days.

• Apples and pears: remove dead and diseased wood first, then water sprouts, crossing branches and branches growing into the center, to open the canopy for light and airflow. That airflow is important for limiting fire blight and scab. Start with the largest, oldest trees.
• Stone fruit: prune plums and cherries after apples. Cut out black knot galls well below the swelling.
• Grapes: per Iowa State Extension, prune grapes in late winter while dormant. Most of last year's growth is removed, leaving a limited number of buds on renewal spurs or canes. Bleeding from grape cuts is normal.
• Raspberries: remove the canes that fruited last summer if you did not cut them in fall. Thin summer-bearing types to the strongest canes. Fall-bearing raspberries grown for one fall crop can be mowed or cut to the ground.

See how to prune fruit trees for the cuts in detail.

Dormant oil: prepare now, spray later

Dormant horticultural oil smothers overwintering scale insects and the eggs of mites and aphids on fruit trees and ornamentals. Per Iowa State Extension, apply it in early spring before the buds open, on a day when the temperature is above 40°F and will not fall below freezing for at least 24 hours.

• Zones 4–5: early-to-mid March is typical, as the March guide notes. February is usually too cold.
• Zone 6: a mild spell in late February can work if the forecast cooperates.
• Spray only where there is a known problem, such as scale on euonymus, magnolia or fruit trees, or a history of mites. Dormant oil is not a routine treatment.
• Read the label for sensitive plants. Blue spruce loses its blue color after an oil spray.

Purdue Landscape Report covers which pests dormant oil controls and why it is gentle on beneficial insects.

Soil, lawn and early-season prep

• Stay out of wet soil. Midwest clay soils stay saturated after a February thaw. Use the squeeze test from the March guide: if a handful holds a ball and does not crumble when poked, keep off it. Working wet soil damages its structure for the whole season.
• Spread compost on beds when the ground is frozen firm enough to walk on. Work it in later.
• Lawn: no fertilizer or crabgrass preventer yet. The March guide puts pre-emergent timing at mid-April in zone 6 and late April in zone 5. Stay off frozen turf.
• Cold frames and row cover: zone 6 gardeners can set up cold frames now to warm the soil for early lettuce and spinach in March. See building a cold frame.
• Forced branches: cut forsythia, pussy willow or flowering quince stems on a mild day, recut them under water, and bring them indoors to bloom. Take them from stems you would thin out anyway.

Winter damage checks

• Rabbits and voles: late winter is often when gnawing damage peaks. As snow settles, check trunk guards and look for chewed bark at the base of young trees and shrubs.
• Salt: keep shoveling salty snow away from beds. Once the soil thaws in March, deep watering helps flush salt from root zones.
• Snow and ice: brush heavy snow off evergreens from below, and let ice melt.
• Heaving: after thaws, press heaved perennials back into the soil and add mulch. Leave winter mulch in place until new growth starts.
• Stored bulbs: check dahlias and cannas one more time. Pot up cannas and tuberous begonias indoors in March for an early start.

Common mistakes

Frequently asked

When should I start onion seeds in the Midwest?

Onions need roughly 10–12 weeks indoors before transplanting. That puts sowing in early-to-mid February in zone 5, late February in zone 4, and late January to early February in zone 6. Iowa State Extension places onion sowing for Iowa in February.

Is February too early to prune fruit trees in the Midwest?

In zone 6 it is fine on mild days in late February. In zones 4–5, UMN Extension favors late winter before bud swell, which is mostly March. Early-winter pruning can lead to cold injury around the cuts. Late winter avoids that and still finishes before growth starts.

My maple is dripping sap where I pruned it. Is that a problem?

No. Iowa State Extension notes that sap bleeding from late-winter cuts on maples, birches and walnuts does not harm the tree. If it bothers you, prune those species in early summer instead.

Can I uncover my perennials during a February warm spell?

No. Leave winter mulch in place through February and March. Thaws are usually followed by hard freezes, and the mulch is what prevents heaving. Pull it back gradually once steady spring growth begins.

Sources

1. I would like to start some onion plants indoors. When should I sow the seeds?, Iowa State University Extension
2. When Should I Start My Seeds?, University of Illinois Extension
3. Late Winter Recommended for Pruning Chores, Purdue Consumer Horticulture
4. Proper Time to Prune Trees and Shrubs, Iowa State University Extension
5. Pruning and Training Apple Trees, University of Minnesota Extension
6. Late Winter/Early Spring Pruning of Small Fruits, Iowa State University Extension
7. When should I apply a dormant oil spray to my fruit trees?, Iowa State University Extension
8. Oak Wilt in Minnesota, University of Minnesota Extension

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