March in the Midwest is fundamentally different north to south. Minneapolis (zone 4b) averages its last frost on May 7; Kansas City (zone 6a) averages April 13; Chicago (zone 5b/6a border) averages April 22. These differences translate to completely different March priorities. What a Missouri gardener is transplanting to the garden, a Minnesota gardener is still starting under lights.
Per UMN Extension, working with your local last frost date rather than general "Midwest" advice is essential.
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Indoor seed starting by zone
Per UMN Extension and University of Illinois Extension:
Zone 4 (Minneapolis, St. Paul, zone 4 MN/WI):
- Last frost ~May 7
- Start peppers: March 1—7
- Start tomatoes: March 15—22
- Start eggplant: March 1—7
Zone 5 (Chicago, Milwaukee, Des Moines):
- Last frost ~April 22—May 3 depending on location
- Start peppers: February 20—28 (if not done)
- Start tomatoes: March 7—14
- Start eggplant: February 20—28
Zone 6 (St. Louis, Columbus, Indianapolis):
- Last frost ~April 7—15
- Start peppers: late February (if not done)
- Start tomatoes: late February—early March
- Most warm-season crops already started
Per UMN Extension, growing conditions for indoor starts: soil temperature 70—80°F for germination (use seedling heat mat); light must be artificial and positioned 2—3 inches from seedlings for 14—16 hours daily; room temperature dropped to 60—65°F after germination for stocky growth.
Pruning in March (Midwest)
Per UMN Extension:
Prune now (late winter, before bud break):
- Roses: cut back Knock Out and shrub roses by one-third to one-half; prune hybrid teas to healthy outward-facing buds
- Fruit trees (apple, pear, plum): dormant pruning is the correct timing — before any bud swell; remove crossing branches, water sprouts, dead wood
- Summer-blooming shrubs (hydrangea paniculata, spirea, potentilla): cut back before growth begins; these bloom on new wood
- Ornamental grasses: cut back to 3—5 inches before new growth emerges; zone 4 grasses are typically cut in March or early April when new shoots begin
Do not prune:
- Lilac, forsythia, spring-blooming spirea: wait until after bloom (May in most zones)
- Oaks: per UMN Extension, do not prune oaks from April through July, when the sap beetles that carry the oak wilt fungus are active; prune them in winter while they are dormant. If an oak is wounded during that window, cover the wound right away with latex paint
Soil preparation
Per University of Illinois Extension, March soil work in the Midwest depends heavily on winter precipitation patterns:
- In a dry winter/early spring: soil may be workable in zone 6 by late February—early March
- In a wet year or clay-heavy soil: soil may not be workable until mid-April in zone 5
The squeeze test applies here as for the Northeast: squeeze a handful; if it holds its shape without crumbling when poked, wait. Per University of Illinois Extension, working wet soil destroys aggregates and creates compaction that persists through the season.
March soil tasks (when dry enough):
- Apply compost (2—3 inches) to beds; work in lightly
- Apply lime per soil test results (test soil every 3 years)
- In zone 6: install floating row cover frames for early cool-season planting in the second half of March
Cool-season crops (zone 6 Midwest)
Per University of Illinois Extension, zone 6 Midwest gardeners can direct sow:
- Peas: sow when soil is workable and 45°F+, typically March 20—April 1 in zone 6
- Spinach: sow when soil is workable; tolerates light frost
- Radishes: sow March 20+ in zone 6
- Lettuce: sow late March with floating row cover protection
Zone 5 (Chicago, Milwaukee): cool-season direct sowing typically starts April 1—15. March outdoor planting is premature in most years.
Lawn care in the Midwest
Per UMN Extension:
- Don't apply fertilizer in early spring to cool-season lawns (Kentucky bluegrass, fescue, ryegrass): per UMN, early spring N produces excessive shoot growth and weakens root development; the primary fertilization window for cool-season lawns is fall (September—October)
- Timing for pre-emergent crabgrass preventer control: apply when soil temperature at 2 inches reaches 55°F for 3 consecutive days; in zone 5, this typically falls in late April; in zone 6, mid-April; NOT in March in the Midwest
- Wait to begin mowing: don't mow until grass is actively growing and soil has dried; mowing saturated soil creates ruts
Fruit tree care
March is the best month for dormant pruning of fruit trees in the Midwest. Per UMN Extension, goals of dormant pruning:
- Establish an open center or central leader structure (depending on species)
- Remove crossing or rubbing branches
- Remove water sprouts (vertical upright branches growing from main scaffold branches)
- Thin the canopy to improve light penetration and air circulation — key to reducing fire blight in apples and pears
Per UMN Extension, apply dormant oil spray to control scale insects and mite eggs while trees are dormant and before bud swell — typically early—mid March in zones 4—5. Apply when temperatures are above 40°F and below 90°F, with no rain expected for 24 hours.
Common mistakes
| Mistake | Consequence | Correct approach |
|---|---|---|
| Starting tomatoes in early February (zone 5) | Overgrown, rootbound transplants that don't thrive | Start 6—8 weeks before last frost; March 7—14 for Chicago |
| Pruning oaks in spring | Oak wilt infection risk | Prune oaks in winter; never April through July |
| Tilling wet clay soil | Destroys soil structure | Wait for proper soil moisture |
| Applying fertilizer to cool-season lawn in March | Excessive shoot growth, poor root development | Fertilize cool-season lawns in fall |
Frequently asked questions
When can I plant trees and shrubs in the Midwest? Per UMN Extension, bareroot trees and shrubs can be planted as soon as the soil is workable — often mid-March to early April in zone 5—6. Container-grown plants can be planted any time from April through fall, but spring and fall are preferred over summer. Bareroot planting in early spring before bud break gives roots a head start before leaves emerge and increase water demand.
Should I remove tree wrap from young trees in March? Per UMN Extension, yes. Remove paper tree wrap in March — leaving it on into spring traps moisture and can harbor disease and insects. Tree wrap is intended only for the first winter after planting for thin-barked species (maple, apple, crabapple) in zone 4—5.
When is the right time to apply dormant oil to fruit trees? Per UMN Extension, apply dormant oil in early spring before buds break and when temperatures are above 40°F during application and won't drop below 32°F within 24 hours. Applying during active bud swell or bloom causes damage.
Recommended gear: Best Floating Row Covers for Pest Exclusion (2026) — our buying guide, with picks weighed against university Extension guidance and product labels.
Sources
- UMN Extension — Vegetable Garden Planting Schedule
- University of Illinois Extension — Vegetable Garden
- UMN Extension — Pruning Trees and Shrubs
- UMN Extension — Lawn Care