Season shown in 6 of Ohio's 88 counties. Explore Ohio
No result yet (10)
Recorded, too few records for a result (65)
Recorded, season not shown (7)
Season shown (6)
Boundaries: U.S. Census Bureau, 2025 Cartographic Boundary Files, 1:500,000. Show as a table
Counties as a table
giant 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
82 · Season shown
Auglaize County
No qualifying records yet
Belmont County
Recorded, too few records for a result
Brown County
No qualifying records yet
Butler County
45 · Season shown
Carroll County
Recorded, too few records for a result
Champaign County
Recorded, too few records for a result
Clark County
Recorded, too few records for a result
Clermont County
Recorded, too few records for a result
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
21 · Season shown
Darke County
Recorded, too few records for a result
Defiance County
Recorded, too few records for a result
Delaware County
27 · 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
111 · Season shown
Fulton County
Recorded, too few records for a result
Gallia County
Recorded, too few records for a result
Geauga County
Recorded, too few records for a result
Greene County
37 · Recorded, season not shown
Guernsey County
Recorded, too few records for a result
Hamilton County
120 · Recorded, season not shown
Hancock County
Recorded, too few records for a result
Hardin County
Recorded, too few records for a result
Harrison County
Recorded, too few records for a result
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
Recorded, too few records for a result
Jefferson County
Recorded, too few records for a result
Knox County
Recorded, too few records for a result
Lake County
No qualifying records yet
Lawrence County
Recorded, too few records for a result
Licking County
Recorded, too few records for a result
Logan County
Recorded, too few records for a result
Lorain County
Recorded, too few records for a result
Lucas County
20 · 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
No qualifying records yet
Mercer County
No qualifying records yet
Miami County
Recorded, too few records for a result
Monroe County
No qualifying records yet
Montgomery County
45 · 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
Recorded, too few records for a result
Perry County
No qualifying records yet
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
No qualifying records yet
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
No qualifying records yet
Stark County
Recorded, too few records for a result
Summit County
51 · 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
33 · Season shown
Washington County
Recorded, too few records for a result
Wayne County
23 · Recorded, season not shown
Williams County
Recorded, too few records for a result
Wood County
27 · 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 Summit County
Early June to mid-September, middle week Aug 9–15
Middle week · Aug 9–15
This week · Nov 8–14
JanFebMarAprMayJunJulAugSepOctNovDec
Show over the bars
Recording in Summit County · records of all species each week, 106,876 in all
Records per week from 51 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 47 dates. Latest record: October 2025.
Show as a table
Records of giant ragweed in Summit County each week, and records of all species
Week
Records of giant ragweed
Years recorded
Records of all species
Jan 4–10
0
0
711
Jan 11–17
0
0
665
Jan 18–24
0
0
601
Jan 25–31
0
0
526
Feb 1–7
0
0
608
Feb 8–14
0
0
619
Feb 15–21
0
0
629
Feb 22–28
0
0
748
Mar 1–7
0
0
728
Mar 8–14
0
0
852
Mar 15–21
0
0
1,055
Mar 22–28
0
0
1,007
Mar 29 – Apr 4
0
0
1,005
Apr 5–11
0
0
1,654
Apr 12–18
0
0
2,454
Apr 19–25
0
0
2,699
Apr 26 – May 2
0
0
3,970
May 3–9
0
0
3,569
May 10–16
0
0
4,053
May 17–23
0
0
3,509
May 24–30
0
0
4,045
May 31 – Jun 6
3
3
2,874
Jun 7–13
1
1
3,158
Jun 14–20
3
2
3,796
Jun 21–27
1
1
3,501
Jun 28 – Jul 4
3
3
3,968
Jul 5–11
1
1
3,632
Jul 12–18
0
0
4,051
Jul 19–25
3
2
3,855
Jul 26 – Aug 1
5
4
2,908
Aug 2–8
3
3
3,828
Aug 9–15
7
2
3,583
Aug 16–22
4
3
3,535
Aug 23–29
3
2
2,939
Aug 30 – Sep 5
2
1
2,840
Sep 6–12
2
2
2,758
Sep 13–19
7
4
2,761
Sep 20–26
0
0
2,646
Sep 27 – Oct 3
1
1
2,089
Oct 4–10
0
0
2,317
Oct 11–17
1
1
1,944
Oct 18–24
0
0
1,314
Oct 25–31
1
1
1,272
Nov 1–7
0
0
786
Nov 8–14
0
0
761
Nov 15–21
0
0
654
Nov 22–28
0
0
703
Nov 29 – Dec 5
0
0
503
Dec 6–12
0
0
447
Dec 13–19
0
0
496
Dec 20–26
0
0
522
Dec 27 – Jan 2
0
0
728
Reported in flower
Only 1 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
Late May to late September, 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 1,271 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 635 dates. Latest record: October 2025.
Show as a table
Records of giant ragweed in Ohio each week, and records of all species
Week
Records of giant 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
0
0
8,321
Mar 8–14
1
1
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
1
1
39,925
Apr 19–25
0
0
41,623
Apr 26 – May 2
9
4
56,391
May 3–9
11
6
52,952
May 10–16
11
4
53,785
May 17–23
26
6
57,698
May 24–30
29
7
54,651
May 31 – Jun 6
29
8
53,099
Jun 7–13
32
8
53,700
Jun 14–20
41
8
56,625
Jun 21–27
42
8
55,361
Jun 28 – Jul 4
33
8
58,477
Jul 5–11
42
7
61,336
Jul 12–18
38
9
64,722
Jul 19–25
43
8
69,753
Jul 26 – Aug 1
46
9
59,416
Aug 2–8
55
9
59,712
Aug 9–15
99
8
55,994
Aug 16–22
92
9
54,328
Aug 23–29
104
10
51,772
Aug 30 – Sep 5
141
9
57,167
Sep 6–12
124
9
59,075
Sep 13–19
115
8
54,543
Sep 20–26
38
7
45,860
Sep 27 – Oct 3
27
7
43,180
Oct 4–10
20
6
37,841
Oct 11–17
12
6
30,824
Oct 18–24
5
3
21,156
Oct 25–31
4
4
19,021
Nov 1–7
0
0
14,172
Nov 8–14
0
0
12,621
Nov 15–21
0
0
7,965
Nov 22–28
0
0
8,136
Nov 29 – Dec 5
0
0
6,083
Dec 6–12
0
0
6,004
Dec 13–19
1
1
5,423
Dec 20–26
0
0
5,661
Dec 27 – Jan 2
0
0
8,459
Reported in flower
Usually reported in flower early August to mid-September, middle week Aug 30 – Sep 5.
From 49 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
Only 15 records here show fruit, too few to show a fruiting season. One needs at least 20 records from 5 different years.
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.
brown-eyed SusanRudbeckia trilobaOften confused in Ohio: 21 identifications in Ohio named one where the other was meant
common ragweedAmbrosia artemisiifoliaOften confused in Ohio: 17 identifications in Ohio named one where the other was meant
cutleaf coneflowerRudbeckia laciniataOften confused in Ohio: 14 identifications in Ohio named one where the other was meant
sassafrasSassafras albidum76 identifications worldwide named one where the other was meant
purple passionflowerPassiflora incarnata74 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: no record
Mar: recorded
Apr: recorded
May: recorded
Jun: recorded
Jul: recorded
Aug: recorded
Sep: recorded
Oct: recorded
Nov: no record
Dec: recorded
Not reported in Ohio in January to February and November, 2016 to 2025.
Land cover where it is recorded
Land cover
Its recordsAll Ohio records
Developed
53%49%
Farmland
24%11%
Forest
19%31%
Wetland
3%5%
Open water
0.7%3%
Grassland and shrub
0.2%0.9%
From 837 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.
