Season shown in 10 of Ohio's 88 counties. Explore Ohio
No result yet (12)
Recorded, too few records for a result (52)
Recorded, season not shown (14)
Season shown (10)
Boundaries: U.S. Census Bureau, 2025 Cartographic Boundary Files, 1:500,000. Show as a table
Counties as a table
swamp milkweed by Ohio county: records and mapped range
County
Records
Adams County
Recorded, too few records for a result
Allen County
Recorded, too few records for a result
Ashland County
Recorded, too few records for a result
Ashtabula County
Recorded, too few records for a result
Athens County
20 · Recorded, season not shown
Auglaize County
No qualifying records yet
Belmont County
Recorded, too few records for a result
Brown County
Recorded, too few records for a result
Butler County
21 · Season shown
Carroll County
No qualifying records yet
Champaign County
27 · Recorded, season not shown
Clark County
Recorded, too few records for a result
Clermont County
36 · Recorded, season not shown
Clinton County
Recorded, too few records for a result
Columbiana County
Recorded, too few records for a result
Coshocton County
Recorded, too few records for a result
Crawford County
Recorded, too few records for a result
Cuyahoga County
163 · Season shown
Darke County
Recorded, too few records for a result
Defiance County
No qualifying records yet
Delaware County
36 · Recorded, season not shown
Erie County
23 · Recorded, season not shown
Fairfield County
Recorded, too few records for a result
Fayette County
Recorded, too few records for a result
Franklin County
145 · Season shown
Fulton County
Recorded, too few records for a result
Gallia County
No qualifying records yet
Geauga County
42 · Season shown
Greene County
30 · Recorded, season not shown
Guernsey County
No qualifying records yet
Hamilton County
101 · Season shown
Hancock County
Recorded, too few records for a result
Hardin County
Recorded, too few records for a result
Harrison County
No qualifying records yet
Henry County
Recorded, too few records for a result
Highland County
Recorded, too few records for a result
Hocking County
Recorded, too few records for a result
Holmes County
Recorded, too few records for a result
Huron County
Recorded, too few records for a result
Jackson County
No qualifying records yet
Jefferson County
Recorded, too few records for a result
Knox County
Recorded, too few records for a result
Lake County
36 · Recorded, season not shown
Lawrence County
Recorded, too few records for a result
Licking County
34 · Recorded, season not shown
Logan County
Recorded, too few records for a result
Lorain County
50 · Season shown
Lucas County
86 · Recorded, season not shown
Madison County
Recorded, too few records for a result
Mahoning County
Recorded, too few records for a result
Marion County
Recorded, too few records for a result
Medina County
43 · Season shown
Meigs County
Recorded, too few records for a result
Mercer County
Recorded, too few records for a result
Miami County
Recorded, too few records for a result
Monroe County
Recorded, too few records for a result
Montgomery County
Recorded, too few records for a result
Morgan County
Recorded, too few records for a result
Morrow County
Recorded, too few records for a result
Muskingum County
Recorded, too few records for a result
Noble County
No qualifying records yet
Ottawa County
23 · Season shown
Paulding County
No qualifying records yet
Perry County
Recorded, too few records for a result
Pickaway County
Recorded, too few records for a result
Pike County
Recorded, too few records for a result
Portage County
31 · Recorded, season not shown
Preble County
Recorded, too few records for a result
Putnam County
No qualifying records yet
Richland County
21 · Recorded, season not shown
Ross County
No qualifying records yet
Sandusky County
Recorded, too few records for a result
Scioto County
Recorded, too few records for a result
Seneca County
Recorded, too few records for a result
Shelby County
Recorded, too few records for a result
Stark County
38 · Recorded, season not shown
Summit County
122 · Season shown
Trumbull County
Recorded, too few records for a result
Tuscarawas County
Recorded, too few records for a result
Union County
Recorded, too few records for a result
Van Wert County
No qualifying records yet
Vinton County
Recorded, too few records for a result
Warren County
40 · Recorded, season not shown
Washington County
Recorded, too few records for a result
Wayne County
27 · Recorded, season not shown
Williams County
Recorded, too few records for a result
Wood County
55 · Season shown
Wyandot County
Recorded, too few records for a result
No mapped range from the range source used, the USGS Gap Analysis Project, which maps land vertebrates only.
Season
When it is recorded
In Hamilton County
Late May to mid-September, middle week Aug 2–8
Middle week · Aug 2–8
This week · Nov 8–14
JanFebMarAprMayJunJulAugSepOctNovDec
Show over the bars
Recording in Hamilton County · records of all species each week, 87,019 in all
Records per week from 101 records in 9 of the 10 years from 2016 to 2025. Shows when people recorded it, not how common it is. The grey bars show how many records of all species were made here each week, so you can see when recording itself was high or low; the season is not adjusted by them.
Recorded on 85 dates. Latest record: August 2025.
Show as a table
Records of swamp milkweed in Hamilton County each week, and records of all species
Week
Records of swamp milkweed
Years recorded
Records of all species
Jan 4–10
0
0
392
Jan 11–17
0
0
344
Jan 18–24
0
0
312
Jan 25–31
0
0
206
Feb 1–7
0
0
357
Feb 8–14
0
0
383
Feb 15–21
0
0
366
Feb 22–28
0
0
391
Mar 1–7
0
0
551
Mar 8–14
0
0
523
Mar 15–21
0
0
750
Mar 22–28
0
0
1,012
Mar 29 – Apr 4
0
0
1,535
Apr 5–11
0
0
1,960
Apr 12–18
0
0
2,492
Apr 19–25
0
0
2,403
Apr 26 – May 2
0
0
3,783
May 3–9
0
0
3,307
May 10–16
0
0
2,059
May 17–23
1
1
2,153
May 24–30
4
3
2,390
May 31 – Jun 6
1
1
2,648
Jun 7–13
0
0
2,715
Jun 14–20
4
3
2,695
Jun 21–27
3
3
2,714
Jun 28 – Jul 4
6
4
3,220
Jul 5–11
4
3
2,980
Jul 12–18
10
5
3,031
Jul 19–25
10
4
2,961
Jul 26 – Aug 1
7
4
2,795
Aug 2–8
16
5
2,884
Aug 9–15
10
7
2,696
Aug 16–22
12
6
2,535
Aug 23–29
6
4
2,536
Aug 30 – Sep 5
1
1
2,606
Sep 6–12
0
0
2,980
Sep 13–19
3
3
2,959
Sep 20–26
2
2
2,313
Sep 27 – Oct 3
1
1
2,122
Oct 4–10
0
0
1,828
Oct 11–17
0
0
1,793
Oct 18–24
0
0
1,338
Oct 25–31
0
0
1,023
Nov 1–7
0
0
676
Nov 8–14
0
0
593
Nov 15–21
0
0
384
Nov 22–28
0
0
496
Nov 29 – Dec 5
0
0
356
Dec 6–12
0
0
478
Dec 13–19
0
0
285
Dec 20–26
0
0
322
Dec 27 – Jan 2
0
0
388
Reported in flower
Only 12 records here show flowers, too few to show a flowering season. One needs at least 20 records from 5 different years.
Reported in fruit
No records here show fruit yet, so there is no fruiting season to show. One needs at least 20 records from 5 different years.
In Ohio
Mid-June to mid-September, middle week Jul 26 – Aug 1
Middle week · Jul 26 – Aug 1
This week · Nov 8–14
JanFebMarAprMayJunJulAugSepOctNovDec
Show over the bars
Recording in Ohio · records of all species each week, 1,691,199 in all
Records per week from 2,111 records in 10 of the 10 years from 2016 to 2025. Shows when people recorded it, not how common it is. The grey bars show how many records of all species were made here each week, so you can see when recording itself was high or low; the season is not adjusted by them.
Recorded on 723 dates. Latest record: October 2025.
Show as a table
Records of swamp milkweed in Ohio each week, and records of all species
Week
Records of swamp milkweed
Years recorded
Records of all species
Jan 4–10
0
0
6,211
Jan 11–17
0
0
5,146
Jan 18–24
0
0
4,645
Jan 25–31
0
0
4,698
Feb 1–7
0
0
6,023
Feb 8–14
1
1
5,888
Feb 15–21
1
1
5,436
Feb 22–28
0
0
6,846
Mar 1–7
0
0
8,321
Mar 8–14
0
0
10,384
Mar 15–21
0
0
12,620
Mar 22–28
1
1
13,949
Mar 29 – Apr 4
0
0
19,661
Apr 5–11
0
0
26,860
Apr 12–18
1
1
39,925
Apr 19–25
0
0
41,623
Apr 26 – May 2
1
1
56,391
May 3–9
0
0
52,952
May 10–16
1
1
53,785
May 17–23
6
4
57,698
May 24–30
9
5
54,651
May 31 – Jun 6
14
6
53,099
Jun 7–13
33
9
53,700
Jun 14–20
47
9
56,625
Jun 21–27
57
9
55,361
Jun 28 – Jul 4
113
10
58,477
Jul 5–11
170
10
61,336
Jul 12–18
204
10
64,722
Jul 19–25
272
10
69,753
Jul 26 – Aug 1
248
10
59,416
Aug 2–8
260
10
59,712
Aug 9–15
226
10
55,994
Aug 16–22
149
9
54,328
Aug 23–29
81
10
51,772
Aug 30 – Sep 5
34
7
57,167
Sep 6–12
42
7
59,075
Sep 13–19
25
7
54,543
Sep 20–26
33
10
45,860
Sep 27 – Oct 3
32
8
43,180
Oct 4–10
24
6
37,841
Oct 11–17
14
6
30,824
Oct 18–24
4
3
21,156
Oct 25–31
4
4
19,021
Nov 1–7
2
2
14,172
Nov 8–14
1
1
12,621
Nov 15–21
0
0
7,965
Nov 22–28
1
1
8,136
Nov 29 – Dec 5
0
0
6,083
Dec 6–12
0
0
6,004
Dec 13–19
0
0
5,423
Dec 20–26
0
0
5,661
Dec 27 – Jan 2
0
0
8,459
Reported in flower
Usually reported in flower late June to late August, middle week Jul 26 – Aug 1.
From 172 records that show flowers. Not every photo of a plant in flower is marked as flowering, so this shows when people reported it in flower, not when it flowers.
Reported in fruit
No fruiting season shown here. Most records come from a single year, so a season is not shown yet.
What these results show
These results show when people recorded a species, not when or where it occurs. Missing weeks and low counts do not mean absence or scarcity, and counts are not abundance. Contributed records reflect where, when and what people chose to observe.
common milkweedAsclepias syriacaOften confused in Ohio: 16 identifications in Ohio named one where the other was meant
butterfly milkweedAsclepias tuberosa162 identifications worldwide named one where the other was meant
spotted Joe-Pye weedEutrochium maculatum129 identifications worldwide named one where the other was meant
purple milkweedAsclepias purpurascens88 identifications worldwide named one where the other was meant
hemp dogbaneApocynum cannabinum76 identifications worldwide named one where the other was meant
From iNaturalist’s similar-species counts, refreshed monthly: confusions in Ohio first, then worldwide. Only species with an Ohio result are listed.
Months not reported
Jan: no record
Feb: recorded
Mar: recorded
Apr: recorded
May: recorded
Jun: recorded
Jul: recorded
Aug: recorded
Sep: recorded
Oct: recorded
Nov: recorded
Dec: no record
Not reported in Ohio in December to January, 2016 to 2025.
Land cover where it is recorded
Land cover
Its recordsAll Ohio records
Developed
51%49%
Farmland
20%11%
Forest
13%31%
Wetland
10%5%
Open water
3%3%
Grassland and shrub
2%0.9%
Barren
1%0.6%
From 1,237 records placed within 100 m, beside all Ohio records placed the same way. People record where they go, so this shows where records come from, not where the species lives. Land cover: USGS Annual NLCD, 2025 (opens in a new tab)
Finer identifications
Some Ohio records of this species were identified to a subspecies:
Every one of these records counts toward swamp milkweed's season above.
Why some records go further than species
Many plants vary from place to place. Botanists name these groups at three levels below species: subspecies, variety and form, from the broadest difference to the smallest. Observers and experts only identify a record that far when it shows enough detail to tell them apart. Records without that detail count at the species level.
Names: Catalogue of Life.
Sources
Where these results come from
Records from iNaturalist research-grade observations and expert-identified GBIF datasets, CC0, CC BY and CC BY-NC. Sources
Seasons use the published method and its evidence thresholds. Methods
A spreadsheet (CSV) with a link to each record, on iNaturalist or GBIF. Records whose location was hidden by the observer or the source are counted but not linked.
