Season shown in 10 of Ohio's 88 counties. Explore Ohio
No result yet (12)
Recorded, too few records for a result (60)
Recorded, season not shown (6)
Season shown (10)
Boundaries: U.S. Census Bureau, 2025 Cartographic Boundary Files, 1:500,000. Show as a table
Counties as a table
common ragweed 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
174 · Recorded, season not shown
Auglaize County
Recorded, too few records for a result
Belmont County
Recorded, too few records for a result
Brown County
Recorded, too few records for a result
Butler County
76 · Season shown
Carroll County
Recorded, too few records for a result
Champaign County
No qualifying records yet
Clark County
Recorded, too few records for a result
Clermont County
34 · Season 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
No qualifying records yet
Cuyahoga County
46 · Season shown
Darke County
Recorded, too few records for a result
Defiance County
Recorded, too few records for a result
Delaware County
37 · Recorded, season not shown
Erie County
Recorded, too few records for a result
Fairfield County
Recorded, too few records for a result
Fayette County
Recorded, too few records for a result
Franklin County
123 · Season shown
Fulton County
No qualifying records yet
Gallia County
Recorded, too few records for a result
Geauga County
Recorded, too few records for a result
Greene County
37 · Season shown
Guernsey County
Recorded, too few records for a result
Hamilton County
116 · 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
No qualifying records yet
Highland County
Recorded, too few records for a result
Hocking County
Recorded, too few records for a result
Holmes County
No qualifying records yet
Huron County
No qualifying records yet
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
Recorded, too few records for a result
Lawrence County
No qualifying records yet
Licking County
20 · Season shown
Logan County
Recorded, too few records for a result
Lorain County
Recorded, too few records for a result
Lucas County
45 · 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
Recorded, too few records for a result
Meigs County
Recorded, too few records for a result
Mercer County
No qualifying records yet
Miami County
Recorded, too few records for a result
Monroe County
Recorded, too few records for a result
Montgomery County
27 · Recorded, season not shown
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
Recorded, too few records for a result
Ottawa County
Recorded, too few records for a result
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
Recorded, too few records for a result
Preble County
Recorded, too few records for a result
Putnam County
Recorded, too few records for a result
Richland County
Recorded, too few records for a result
Ross County
Recorded, too few records for a result
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
26 · Season shown
Summit County
49 · 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
34 · Season shown
Washington County
Recorded, too few records for a result
Wayne County
21 · Recorded, season not shown
Williams County
Recorded, too few records for a result
Wood County
29 · Recorded, season not 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 Wayne County
Not enough evidence
Most records come from a single year, so a season is not shown yet. Based on 21 records in 6 of the 10 years from 2016 to 2025, above the minimum of 20 records from 5 different years.
JanFebMarAprMayJunJulAugSepOctNovDec
Show over the bars
Recording in Wayne County · records of all species each week, 15,874 in all
Records per week from 21 records in 6 of the 10 years from 2016 to 2025. Shows when people recorded it, not a season or how common it is.
Show as a table
Records of common ragweed in Wayne County each week, and records of all species
Week
Records of common ragweed
Years recorded
Records of all species
Jan 4–10
0
0
52
Jan 11–17
0
0
27
Jan 18–24
0
0
13
Jan 25–31
0
0
35
Feb 1–7
0
0
52
Feb 8–14
0
0
52
Feb 15–21
0
0
35
Feb 22–28
0
0
67
Mar 1–7
0
0
83
Mar 8–14
0
0
89
Mar 15–21
0
0
127
Mar 22–28
0
0
138
Mar 29 – Apr 4
0
0
190
Apr 5–11
0
0
265
Apr 12–18
0
0
352
Apr 19–25
0
0
307
Apr 26 – May 2
0
0
350
May 3–9
0
0
301
May 10–16
0
0
449
May 17–23
0
0
365
May 24–30
0
0
468
May 31 – Jun 6
1
1
455
Jun 7–13
0
0
274
Jun 14–20
1
1
366
Jun 21–27
1
1
441
Jun 28 – Jul 4
0
0
569
Jul 5–11
1
1
639
Jul 12–18
0
0
649
Jul 19–25
0
0
722
Jul 26 – Aug 1
1
1
603
Aug 2–8
0
0
582
Aug 9–15
2
2
786
Aug 16–22
0
0
406
Aug 23–29
1
1
741
Aug 30 – Sep 5
3
3
772
Sep 6–12
1
1
588
Sep 13–19
3
1
696
Sep 20–26
1
1
409
Sep 27 – Oct 3
5
1
520
Oct 4–10
0
0
441
Oct 11–17
0
0
287
Oct 18–24
0
0
218
Oct 25–31
0
0
165
Nov 1–7
0
0
190
Nov 8–14
0
0
134
Nov 15–21
0
0
68
Nov 22–28
0
0
58
Nov 29 – Dec 5
0
0
44
Dec 6–12
0
0
20
Dec 13–19
0
0
31
Dec 20–26
0
0
29
Dec 27 – Jan 2
0
0
154
Reported in flower
No records here show flowers yet, so there is no flowering season to show. One needs at least 20 records from 5 different years.
Reported in fruit
Only 1 records here show fruit, too few to show a fruiting season. One needs at least 20 records from 5 different years.
In Ohio
Early June to early October, middle week Aug 16–22
Middle week · Aug 16–22
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 1,468 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 703 dates. Latest record: November 2025.
Show as a table
Records of common ragweed in Ohio each week, and records of all species
Week
Records of common ragweed
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
0
0
5,888
Feb 15–21
0
0
5,436
Feb 22–28
0
0
6,846
Mar 1–7
1
1
8,321
Mar 8–14
0
0
10,384
Mar 15–21
0
0
12,620
Mar 22–28
0
0
13,949
Mar 29 – Apr 4
0
0
19,661
Apr 5–11
0
0
26,860
Apr 12–18
0
0
39,925
Apr 19–25
1
1
41,623
Apr 26 – May 2
3
3
56,391
May 3–9
3
3
52,952
May 10–16
4
3
53,785
May 17–23
10
7
57,698
May 24–30
14
6
54,651
May 31 – Jun 6
36
8
53,099
Jun 7–13
31
7
53,700
Jun 14–20
53
8
56,625
Jun 21–27
39
7
55,361
Jun 28 – Jul 4
38
7
58,477
Jul 5–11
51
8
61,336
Jul 12–18
52
8
64,722
Jul 19–25
63
7
69,753
Jul 26 – Aug 1
61
8
59,416
Aug 2–8
91
9
59,712
Aug 9–15
111
9
55,994
Aug 16–22
97
10
54,328
Aug 23–29
105
8
51,772
Aug 30 – Sep 5
138
9
57,167
Sep 6–12
132
8
59,075
Sep 13–19
129
8
54,543
Sep 20–26
44
9
45,860
Sep 27 – Oct 3
67
9
43,180
Oct 4–10
61
7
37,841
Oct 11–17
18
6
30,824
Oct 18–24
7
3
21,156
Oct 25–31
1
1
19,021
Nov 1–7
4
3
14,172
Nov 8–14
2
2
12,621
Nov 15–21
0
0
7,965
Nov 22–28
0
0
8,136
Nov 29 – Dec 5
1
1
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
No flowering season shown here. Most records come from a single year, so a season is not shown yet.
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.
giant ragweedAmbrosia trifidaOften confused in Ohio: 17 identifications in Ohio named one where the other was meant
common mugwortArtemisia vulgaris303 identifications worldwide named one where the other was meant
sweet annieArtemisia annua119 identifications worldwide named one where the other was meant
Spanish needlesBidens bipinnata63 identifications worldwide named one where the other was meant
wild carrotDaucus carota49 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: no record
Apr: recorded
May: recorded
Jun: recorded
Jul: recorded
Aug: recorded
Sep: recorded
Oct: recorded
Nov: recorded
Dec: no record
Not reported in Ohio in March and December to January, 2016 to 2025.
Land cover where it is recorded
Land cover
Its recordsAll Ohio records
Developed
64%49%
Farmland
16%11%
Forest
16%31%
Wetland
1%5%
Grassland and shrub
0.9%0.9%
Open water
0.6%3%
Barren
0.4%0.6%
From 1,047 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)
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.
