The milkweed year
What is in flower, where the monarchs are, and what to do about it. Twelve months, written for the middle of the country, with notes on shifting the timings north or south.
January
Overwintering, and the quietest month to plan
4 in flower
February
The first movement north
4 in flower
March
The first generation, and the year turns on it
9 in flower
April
Pushing north
28 in flower
May
Milkweed comes up, monarchs arrive
53 in flower
June
Peak growth, first big bloom
69 in flower
July
The heart of the breeding season
61 in flower
August
The last generation, and the first pods
44 in flower
September
The migration, and the best month for seed
24 in flower
October
Sowing month
6 in flower
November
Clustering begins
4 in flower
December
Counting, and starting again
4 in flower
Bloom chart: all 72 species
Bloom periods across the species' whole range. A species flowering in June in Texas may not flower until August in Minnesota, so read this as the outer envelope rather than a local prediction.
| Species | J | F | M | A | M | J | J | A | S | O | N | D |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Antelope Horns | Not in bloom in January | Not in bloom in February | In bloom in March | Peak bloom in April | Peak bloom in May | In bloom in June | In bloom in July | Not in bloom in August | Not in bloom in September | Not in bloom in October | Not in bloom in November | Not in bloom in December |
| Aquatic Milkweed | Not in bloom in January | Not in bloom in February | Not in bloom in March | Not in bloom in April | In bloom in May | Peak bloom in June | Peak bloom in July | Peak bloom in August | In bloom in September | Not in bloom in October | Not in bloom in November | Not in bloom in December |
| Balloon Plant introduced | Not in bloom in January | Not in bloom in February | Not in bloom in March | Not in bloom in April | In bloom in May | In bloom in June | Peak bloom in July | Peak bloom in August | In bloom in September | In bloom in October | Not in bloom in November | Not in bloom in December |
| Bract Milkweed | Not in bloom in January | Not in bloom in February | Not in bloom in March | In bloom in April | Peak bloom in May | Peak bloom in June | In bloom in July | In bloom in August | Not in bloom in September | Not in bloom in October | Not in bloom in November | Not in bloom in December |
| Broadleaf Milkweed | Not in bloom in January | Not in bloom in February | Not in bloom in March | Not in bloom in April | In bloom in May | Peak bloom in June | Peak bloom in July | In bloom in August | Not in bloom in September | Not in bloom in October | Not in bloom in November | Not in bloom in December |
| Butterfly Weed | Not in bloom in January | Not in bloom in February | Not in bloom in March | Not in bloom in April | In bloom in May | Peak bloom in June | Peak bloom in July | In bloom in August | In bloom in September | Not in bloom in October | Not in bloom in November | Not in bloom in December |
| California Milkweed | Not in bloom in January | Not in bloom in February | Not in bloom in March | In bloom in April | Peak bloom in May | Peak bloom in June | In bloom in July | Not in bloom in August | Not in bloom in September | Not in bloom in October | Not in bloom in November | Not in bloom in December |
| Carolina Milkweed | Not in bloom in January | Not in bloom in February | Not in bloom in March | Not in bloom in April | In bloom in May | Peak bloom in June | In bloom in July | In bloom in August | Not in bloom in September | Not in bloom in October | Not in bloom in November | Not in bloom in December |
| Clasping Milkweed | Not in bloom in January | Not in bloom in February | Not in bloom in March | Not in bloom in April | Peak bloom in May | Peak bloom in June | In bloom in July | Not in bloom in August | Not in bloom in September | Not in bloom in October | Not in bloom in November | Not in bloom in December |
| Common Milkweed | Not in bloom in January | Not in bloom in February | Not in bloom in March | Not in bloom in April | Not in bloom in May | Peak bloom in June | Peak bloom in July | In bloom in August | Not in bloom in September | Not in bloom in October | Not in bloom in November | Not in bloom in December |
| Curtiss’ Milkweed | Not in bloom in January | Not in bloom in February | Not in bloom in March | In bloom in April | Peak bloom in May | Peak bloom in June | In bloom in July | In bloom in August | In bloom in September | Not in bloom in October | Not in bloom in November | Not in bloom in December |
| Desert Milkweed | Not in bloom in January | Not in bloom in February | Not in bloom in March | In bloom in April | Peak bloom in May | Peak bloom in June | In bloom in July | In bloom in August | In bloom in September | Not in bloom in October | Not in bloom in November | Not in bloom in December |
| Dwarf Milkweed | Not in bloom in January | Not in bloom in February | Not in bloom in March | In bloom in April | Peak bloom in May | In bloom in June | Not in bloom in July | Not in bloom in August | Not in bloom in September | Not in bloom in October | Not in bloom in November | Not in bloom in December |
| Eastwood’s Milkweed | Not in bloom in January | Not in bloom in February | Not in bloom in March | Not in bloom in April | Peak bloom in May | Peak bloom in June | Not in bloom in July | Not in bloom in August | Not in bloom in September | Not in bloom in October | Not in bloom in November | Not in bloom in December |
| Emory’s Milkweed | Not in bloom in January | Not in bloom in February | Not in bloom in March | In bloom in April | Peak bloom in May | In bloom in June | In bloom in July | In bloom in August | Peak bloom in September | Not in bloom in October | Not in bloom in November | Not in bloom in December |
| Engelmann’s Milkweed | Not in bloom in January | Not in bloom in February | Not in bloom in March | Not in bloom in April | Not in bloom in May | In bloom in June | Peak bloom in July | In bloom in August | Not in bloom in September | Not in bloom in October | Not in bloom in November | Not in bloom in December |
| Feay’s Milkweed | Not in bloom in January | Not in bloom in February | Not in bloom in March | In bloom in April | Peak bloom in May | Peak bloom in June | In bloom in July | In bloom in August | In bloom in September | Not in bloom in October | Not in bloom in November | Not in bloom in December |
| Fewflower Milkweed | Not in bloom in January | Not in bloom in February | Not in bloom in March | Not in bloom in April | In bloom in May | Peak bloom in June | Peak bloom in July | In bloom in August | Not in bloom in September | Not in bloom in October | Not in bloom in November | Not in bloom in December |
| Fourleaf Milkweed | Not in bloom in January | Not in bloom in February | Not in bloom in March | Not in bloom in April | Peak bloom in May | In bloom in June | Not in bloom in July | Not in bloom in August | Not in bloom in September | Not in bloom in October | Not in bloom in November | Not in bloom in December |
| Giant Milkweed introduced | In bloom in January | In bloom in February | Peak bloom in March | Peak bloom in April | In bloom in May | In bloom in June | In bloom in July | In bloom in August | In bloom in September | Peak bloom in October | In bloom in November | In bloom in December |
| Green Antelopehorn | Not in bloom in January | Not in bloom in February | Not in bloom in March | In bloom in April | Peak bloom in May | Peak bloom in June | In bloom in July | Not in bloom in August | Not in bloom in September | Not in bloom in October | Not in bloom in November | Not in bloom in December |
| Green Comet Milkweed | Not in bloom in January | Not in bloom in February | Not in bloom in March | Not in bloom in April | In bloom in May | Peak bloom in June | Peak bloom in July | In bloom in August | Not in bloom in September | Not in bloom in October | Not in bloom in November | Not in bloom in December |
| Hall’s Milkweed | Not in bloom in January | Not in bloom in February | Not in bloom in March | Not in bloom in April | Not in bloom in May | In bloom in June | Peak bloom in July | In bloom in August | Not in bloom in September | Not in bloom in October | Not in bloom in November | Not in bloom in December |
| Heartleaf Milkweed | Not in bloom in January | Not in bloom in February | Not in bloom in March | Not in bloom in April | Peak bloom in May | Peak bloom in June | In bloom in July | Not in bloom in August | Not in bloom in September | Not in bloom in October | Not in bloom in November | Not in bloom in December |
| Largeflower Milkweed | Not in bloom in January | Not in bloom in February | Not in bloom in March | Not in bloom in April | In bloom in May | Peak bloom in June | Peak bloom in July | In bloom in August | Not in bloom in September | Not in bloom in October | Not in bloom in November | Not in bloom in December |
| Lemmon’s Milkweed | Not in bloom in January | Not in bloom in February | Not in bloom in March | Not in bloom in April | Not in bloom in May | Not in bloom in June | In bloom in July | Peak bloom in August | In bloom in September | Not in bloom in October | Not in bloom in November | Not in bloom in December |
| Longhood Milkweed | Not in bloom in January | Not in bloom in February | Not in bloom in March | In bloom in April | Peak bloom in May | Peak bloom in June | In bloom in July | In bloom in August | Not in bloom in September | Not in bloom in October | Not in bloom in November | Not in bloom in December |
| Longleaf Milkweed | Not in bloom in January | Not in bloom in February | Not in bloom in March | In bloom in April | Peak bloom in May | Peak bloom in June | In bloom in July | Not in bloom in August | Not in bloom in September | Not in bloom in October | Not in bloom in November | Not in bloom in December |
| Mahogany Milkweed | Not in bloom in January | Not in bloom in February | Not in bloom in March | Not in bloom in April | Not in bloom in May | In bloom in June | Peak bloom in July | Peak bloom in August | In bloom in September | Not in bloom in October | Not in bloom in November | Not in bloom in December |
| Mead’s Milkweed | Not in bloom in January | Not in bloom in February | Not in bloom in March | Not in bloom in April | Peak bloom in May | Peak bloom in June | Not in bloom in July | Not in bloom in August | Not in bloom in September | Not in bloom in October | Not in bloom in November | Not in bloom in December |
| Michaux’s Milkweed | Not in bloom in January | Not in bloom in February | Not in bloom in March | In bloom in April | Peak bloom in May | In bloom in June | In bloom in July | Not in bloom in August | Not in bloom in September | Not in bloom in October | Not in bloom in November | Not in bloom in December |
| Mojave Milkweed | Not in bloom in January | Not in bloom in February | Not in bloom in March | In bloom in April | Peak bloom in May | In bloom in June | Not in bloom in July | Not in bloom in August | Not in bloom in September | Not in bloom in October | Not in bloom in November | Not in bloom in December |
| Narrowleaf Milkweed | Not in bloom in January | Not in bloom in February | Not in bloom in March | Not in bloom in April | In bloom in May | Peak bloom in June | Peak bloom in July | Peak bloom in August | In bloom in September | Not in bloom in October | Not in bloom in November | Not in bloom in December |
| Nodding Milkweed | Not in bloom in January | Not in bloom in February | Not in bloom in March | Not in bloom in April | Not in bloom in May | In bloom in June | Peak bloom in July | Peak bloom in August | In bloom in September | Not in bloom in October | Not in bloom in November | Not in bloom in December |
| Oval-leaf Milkweed | Not in bloom in January | Not in bloom in February | Not in bloom in March | Not in bloom in April | Not in bloom in May | Peak bloom in June | In bloom in July | Not in bloom in August | Not in bloom in September | Not in bloom in October | Not in bloom in November | Not in bloom in December |
| Pallid Milkweed | Not in bloom in January | Not in bloom in February | Not in bloom in March | In bloom in April | Peak bloom in May | In bloom in June | Not in bloom in July | Not in bloom in August | Not in bloom in September | Not in bloom in October | Not in bloom in November | Not in bloom in December |
| Pineland Milkweed | Not in bloom in January | Not in bloom in February | Not in bloom in March | Not in bloom in April | Not in bloom in May | In bloom in June | Peak bloom in July | In bloom in August | Not in bloom in September | Not in bloom in October | Not in bloom in November | Not in bloom in December |
| Pineneedle Milkweed | Not in bloom in January | Not in bloom in February | In bloom in March | Peak bloom in April | Peak bloom in May | In bloom in June | In bloom in July | In bloom in August | Peak bloom in September | In bloom in October | Not in bloom in November | Not in bloom in December |
| Pinewoods Milkweed | Not in bloom in January | Not in bloom in February | In bloom in March | Peak bloom in April | Peak bloom in May | In bloom in June | Not in bloom in July | Not in bloom in August | Not in bloom in September | Not in bloom in October | Not in bloom in November | Not in bloom in December |
| Plains Milkweed | Not in bloom in January | Not in bloom in February | Not in bloom in March | Not in bloom in April | Not in bloom in May | In bloom in June | Peak bloom in July | Peak bloom in August | In bloom in September | Not in bloom in October | Not in bloom in November | Not in bloom in December |
| Poison Milkweed | Not in bloom in January | Not in bloom in February | Not in bloom in March | Not in bloom in April | Not in bloom in May | In bloom in June | Peak bloom in July | Peak bloom in August | In bloom in September | Not in bloom in October | Not in bloom in November | Not in bloom in December |
| Poke Milkweed | Not in bloom in January | Not in bloom in February | Not in bloom in March | Not in bloom in April | Not in bloom in May | Peak bloom in June | In bloom in July | Not in bloom in August | Not in bloom in September | Not in bloom in October | Not in bloom in November | Not in bloom in December |
| Prairie Milkweed | Not in bloom in January | Not in bloom in February | Not in bloom in March | Not in bloom in April | Not in bloom in May | Peak bloom in June | Peak bloom in July | Not in bloom in August | Not in bloom in September | Not in bloom in October | Not in bloom in November | Not in bloom in December |
| Prostrate Milkweed | Not in bloom in January | Not in bloom in February | In bloom in March | Peak bloom in April | Peak bloom in May | In bloom in June | In bloom in July | In bloom in August | In bloom in September | Not in bloom in October | Not in bloom in November | Not in bloom in December |
| Purple Milkweed | Not in bloom in January | Not in bloom in February | Not in bloom in March | Not in bloom in April | In bloom in May | Peak bloom in June | In bloom in July | Not in bloom in August | Not in bloom in September | Not in bloom in October | Not in bloom in November | Not in bloom in December |
| Red Milkweed | Not in bloom in January | Not in bloom in February | Not in bloom in March | Not in bloom in April | Not in bloom in May | Peak bloom in June | Peak bloom in July | Not in bloom in August | Not in bloom in September | Not in bloom in October | Not in bloom in November | Not in bloom in December |
| Rusby’s Milkweed | Not in bloom in January | Not in bloom in February | Not in bloom in March | Not in bloom in April | In bloom in May | Peak bloom in June | Peak bloom in July | In bloom in August | Not in bloom in September | Not in bloom in October | Not in bloom in November | Not in bloom in December |
| Rush Milkweed | In bloom in January | In bloom in February | In bloom in March | Peak bloom in April | Peak bloom in May | In bloom in June | In bloom in July | In bloom in August | Peak bloom in September | Peak bloom in October | In bloom in November | In bloom in December |
| Ruth’s Milkweed | Not in bloom in January | Not in bloom in February | Not in bloom in March | In bloom in April | Peak bloom in May | In bloom in June | Not in bloom in July | Not in bloom in August | Not in bloom in September | Not in bloom in October | Not in bloom in November | Not in bloom in December |
| Sand Milkweed | Not in bloom in January | Not in bloom in February | Not in bloom in March | Not in bloom in April | Not in bloom in May | In bloom in June | Peak bloom in July | In bloom in August | Not in bloom in September | Not in bloom in October | Not in bloom in November | Not in bloom in December |
| Savannah Milkweed | Not in bloom in January | Not in bloom in February | Not in bloom in March | In bloom in April | Peak bloom in May | Peak bloom in June | In bloom in July | In bloom in August | In bloom in September | Not in bloom in October | Not in bloom in November | Not in bloom in December |
| Serpentine Milkweed | Not in bloom in January | Not in bloom in February | Not in bloom in March | Not in bloom in April | In bloom in May | Peak bloom in June | In bloom in July | Not in bloom in August | Not in bloom in September | Not in bloom in October | Not in bloom in November | Not in bloom in December |
| Showy Milkweed | Not in bloom in January | Not in bloom in February | Not in bloom in March | Not in bloom in April | In bloom in May | Peak bloom in June | Peak bloom in July | In bloom in August | Not in bloom in September | Not in bloom in October | Not in bloom in November | Not in bloom in December |
| Slimleaf Milkweed | Not in bloom in January | Not in bloom in February | Not in bloom in March | Not in bloom in April | Not in bloom in May | In bloom in June | Peak bloom in July | In bloom in August | Not in bloom in September | Not in bloom in October | Not in bloom in November | Not in bloom in December |
| Slimpod Milkweed | Not in bloom in January | Not in bloom in February | Not in bloom in March | Not in bloom in April | Not in bloom in May | Not in bloom in June | In bloom in July | Peak bloom in August | In bloom in September | Not in bloom in October | Not in bloom in November | Not in bloom in December |
| Southern Milkweed | Not in bloom in January | Not in bloom in February | Not in bloom in March | Not in bloom in April | In bloom in May | Peak bloom in June | Peak bloom in July | In bloom in August | Not in bloom in September | Not in bloom in October | Not in bloom in November | Not in bloom in December |
| Sperry’s Milkweed | Not in bloom in January | Not in bloom in February | Not in bloom in March | Not in bloom in April | In bloom in May | Peak bloom in June | In bloom in July | In bloom in August | Not in bloom in September | Not in bloom in October | Not in bloom in November | Not in bloom in December |
| Swamp Milkweed | Not in bloom in January | Not in bloom in February | Not in bloom in March | Not in bloom in April | Not in bloom in May | In bloom in June | Peak bloom in July | Peak bloom in August | In bloom in September | Not in bloom in October | Not in bloom in November | Not in bloom in December |
| Tall Green Milkweed | Not in bloom in January | Not in bloom in February | Not in bloom in March | Not in bloom in April | Not in bloom in May | In bloom in June | Peak bloom in July | In bloom in August | Not in bloom in September | Not in bloom in October | Not in bloom in November | Not in bloom in December |
| Texas Milkweed | Not in bloom in January | Not in bloom in February | Not in bloom in March | Not in bloom in April | In bloom in May | Peak bloom in June | Peak bloom in July | In bloom in August | In bloom in September | Not in bloom in October | Not in bloom in November | Not in bloom in December |
| Tropical Milkweed introduced | In bloom in January | In bloom in February | In bloom in March | In bloom in April | In bloom in May | Peak bloom in June | Peak bloom in July | Peak bloom in August | Peak bloom in September | In bloom in October | In bloom in November | In bloom in December |
| Tufted Milkweed | Not in bloom in January | Not in bloom in February | Not in bloom in March | In bloom in April | Peak bloom in May | In bloom in June | In bloom in July | In bloom in August | Not in bloom in September | Not in bloom in October | Not in bloom in November | Not in bloom in December |
| Velvetleaf Milkweed | Not in bloom in January | Not in bloom in February | Not in bloom in March | In bloom in April | Peak bloom in May | Peak bloom in June | In bloom in July | Not in bloom in August | Not in bloom in September | Not in bloom in October | Not in bloom in November | Not in bloom in December |
| Welsh’s Milkweed | Not in bloom in January | Not in bloom in February | Not in bloom in March | Not in bloom in April | In bloom in May | Peak bloom in June | In bloom in July | Not in bloom in August | Not in bloom in September | Not in bloom in October | Not in bloom in November | Not in bloom in December |
| Wheel Milkweed | Not in bloom in January | Not in bloom in February | Not in bloom in March | In bloom in April | Peak bloom in May | In bloom in June | Not in bloom in July | Not in bloom in August | Not in bloom in September | Not in bloom in October | Not in bloom in November | Not in bloom in December |
| White Milkweed | Not in bloom in January | Not in bloom in February | Not in bloom in March | Not in bloom in April | In bloom in May | Peak bloom in June | In bloom in July | Not in bloom in August | Not in bloom in September | Not in bloom in October | Not in bloom in November | Not in bloom in December |
| Whitestem Milkweed | In bloom in January | Peak bloom in February | Peak bloom in March | Peak bloom in April | In bloom in May | Not in bloom in June | Not in bloom in July | Not in bloom in August | Not in bloom in September | Not in bloom in October | In bloom in November | In bloom in December |
| Whorled Milkweed | Not in bloom in January | Not in bloom in February | Not in bloom in March | Not in bloom in April | Not in bloom in May | In bloom in June | Peak bloom in July | Peak bloom in August | In bloom in September | Not in bloom in October | Not in bloom in November | Not in bloom in December |
| Woolly Milkweed | Not in bloom in January | Not in bloom in February | Not in bloom in March | Not in bloom in April | In bloom in May | Peak bloom in June | Not in bloom in July | Not in bloom in August | Not in bloom in September | Not in bloom in October | Not in bloom in November | Not in bloom in December |
| Woolly Milkweed | Not in bloom in January | Not in bloom in February | Not in bloom in March | In bloom in April | Peak bloom in May | Peak bloom in June | In bloom in July | Not in bloom in August | Not in bloom in September | Not in bloom in October | Not in bloom in November | Not in bloom in December |
| Woollypod Milkweed | Not in bloom in January | Not in bloom in February | Not in bloom in March | Not in bloom in April | In bloom in May | Peak bloom in June | Peak bloom in July | In bloom in August | Not in bloom in September | Not in bloom in October | Not in bloom in November | Not in bloom in December |
| Zizotes Milkweed | Not in bloom in January | Not in bloom in February | In bloom in March | Peak bloom in April | Peak bloom in May | In bloom in June | In bloom in July | In bloom in August | Peak bloom in September | In bloom in October | Not in bloom in November | Not in bloom in December |
in bloom peak bloom
The three moments that matter most
March and April in the south-central states. Monarchs arriving from Mexico are old and running out of time, and the first generation of the year depends on antelope horns and green antelopehorn being up and in good condition. Nothing else in the calendar has this much leverage.
July and August in the North. The generation that will fly to Mexico is being built now, out of the leaves of common, showy and swamp milkweed.
September and October, everywhere. The migratory generation needs nectar, not host plants, and enormous quantities of it. Goldenrod and asters carry the migration south.