John's wife applied for a widow's pension on 25 Feb 1895, so presumably John died shortly before that date (which pension would have ceased when she remarried).

1.  LDS.  Family Search: Internet Genealogy Service:  IGI - International Genealogical Index (online at FamilySearch.org).

J. G. F. CELLAR Spouse: Naomi LUKE Marriage: 1 Mar 1876, Delaware, Ohio Source: Marriage Records, 1835-1951. Ohio. Probate Court (Delaware County).

2.  1880 Census (indexed at FamilySearch.org; page image online at Ancestry.com, Image #12 of 31):  Liberty Twp., Delaware Co., OH, p. 309D, PN 12, SD 5, ED 104, enumerated 10 Jun 1880, official enumeration date 1 Jun 1880 (extracted by Diana Gale Matthiesen):¤•

1880:  for an explanation of the column headings, please see What the Numbers in the Federal Census Mean (missing columns contained no data).

1

2

3

4

5

6

7

8

9

10

13

24

25

26

110

112

Cellar John ? ?

W

M

49

/

Farmer

Ohio

______ Noma M

W

F

25

Wife

/

Keeping House

Ohio

Ohio

O

______ Mary W

W

F

3

Dau

/

Ohio

O

O

______ John E

W

M

7/12

Oct

Son

/

Ohio

O

O

3.  1890 Census:  the 1890 Census Population Schedules were destroyed.

4.  1900 Census Index/Microfilm (online at Genealogy.com, Image #6 of 28):  Liberty Twp., Delaware Co., OH, p. 189B, SD 7, ED 38, SN 3, enumerated 6 Jun 1900 (extracted by Diana Gale Matthiesen):¤•

1900:  for an explanation of the column headings, please see What the Numbers in the Federal Census Mean (missing columns contained no data).
1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	19	20	22	23	24	25	26	27	28
69	69	Howard Isaac N	Head	W	M	Dec 1847	52	M	4			OH	VA	MD	Farmer	0	Y	Y	Y	O	F	F	65
		______ Naoma	Wife	W	F	Feb 1856	44	M	4	3	3	OH	OH	OH			Y	Y	Y
		Cellars Marry W	Step Daughter	W	F	Sep 1876	23	M	3	0	0	OH	OH	OH			Y	Y	Y
		Cellars John E	Step Son	W	M	O C 1879	20	S				OH	OH	OH	Farm Labor	0	Y	Y	Y

Listed two households from Naomi's sisters-in-law, spinster Sarah W. CELLAR and widow Lucy (CELLAR) KNAPP. 

5.  Anon.  1880.  History of Delaware County and Ohio.  O.L. Baskin, Chicago (online at Heritage Pursuit):

p. 656

LIBERTY TOWNSHIP... JOHN G. F. CELLAR, farming; P.O. Powell; John was born in this township Dec. 15 1837; son of John T. and Lucy (Wilson) Cellar.  John was born on the homestead now occupied by his sister, where he lived until the year previou to his marriage, when he built him a house just south of the homestead, and made preparations for the reception of his prospective wife, and, March 1, 1875, was joined by matrimony to Naomi Luke born in this county Feb. 22, 1856; she is a daughter of John Luke, who married Lucy Karns.  Mr. and Mrs. Cellar have one child Mary W. born Nov. 15, 1876.  He has 124 acres of land.  They are both members of the Presbyterian Church.  He was in the 100-days service in Co. K, 145th O.N.G., and returned home in August, 1864, and since has been engaged in farming pursuits.

Primary records support a birth year of 1835 for John, and his father was John Flanigan CELLAR, not "John T. CELLAR."  County marriage records have our subjects married in 1876, not 1875.  Our subjects had three children, not one, but it's obvious this bio was written before the second and third children were born.  The 1900 Census indicates daughter, Mary, was born in September, not November.  "O.N.G." = Ohio National Guard, more commonly known as the "O.V.I.," Ohio Volunteer Infantry.

6.  American Civil War Soldiers (online at Ancestry.com; missing columns contained no data):

Name	Age	Rank	Unit	Enlist Date	Date/Place Mustered Out
John G. F. Cellar	28	Pvt	Co. K, 145th Ohio Infantry	12 May 1864	24 Aug 1864, Camp Chase, OH

Note that if one is age 28 in 1864, you were born in 1835 or 1836.  John G.F.'s first cousin, John CELLAR, also enlisted and mustered out on the same dates and in the same unit, with the rank of Captain. 

7.  Civil War Pension Index (index and images online at Ancestry.com):

Name of Soldier	Cellar, John G. F.
Name of Dependent	Widow	Cellar, Naomi
	Minor
Service	K 145 Ohio Inf.
Date of Filing	Claim	Application No.	Certificate No.	State from which Filed
188* Nov 15	Invalid	628884	452203	Ohio
1895 Feby 25	Widow	609145	434654	Ohio
	Minor

*1881, 1887, or 1889, I can't tell.  The whole image is blurry and hard to read.