When to Plant Tomatoes

When is it safe to transplant tomatoes outdoors?

The common advice for when to plant tomatoes is after the last frost date. The problem with this advice is that 50% of the time the last frost falls after this date! Tomatoes will not tolerate frost and you'll have to use frost protection measures if freezing temperatures threaten.

Better advice is to wait until two weeks past your average safe date before planting. The safe date is the day on which in meteorological records the last frost date had already occurred 90% of the time. See the table below for many U.S. cities. If you're conservative and wait a little longer until the weather is warmer you'll be rewarded. Your plants will invariably bear more and longer than plants set out very early.

At SeaTac Airport in Seattle, for example, the average last frost date is March 10th and the average 90% safe date is about four weeks later -- April 4th.

To learn all the secrets of easily growing juicy tasty tomatoes at home from a world renowned plant disease and nutritionist who advises professional growers Click Here!

Wait for these temperatures

Not only should you wait till after the safe date, it's best to wait until the soil and air temperatures are no lower than 45˚F (7˚C) at night unless you're prepared to cover your plants. The daytime temperature of the soil should be at least 55 to 60˚F (13 to 16˚C) before transplanting outdoors.

For peace of mind, why not consult your nursery or your local newspaper's garden columnist for when to plant tomatoes? Here in Seattle that would be a colorful character by the name of Ciscoe who authored an excellent gardening book, Ask Ciscoe: Oh, la, la! Your Gardening Questions Answered. Ciscoe recommends setting out tomato plants around Mother's Day (second Sunday in May) in Seattle unless you're planning to use cold frames or some other early-tomato tricks.

When you can ignore this advice

You've read advice on when to plant tomatoes but if you want to have the first ripe tomatoes in the neighborhood you can gamble by setting your plants out early. You'll want to be ready with some frost protection strategies if a late frost looms. Two passive techniques to keep tomatoes warm and protected are to use covers and heat-storing water containers. Some common frost protection methods and devices:

• Garden cloches
• Floating fabric row covers
• HotKaps, a commercially available paper covering
• Cold frames
• Raised beds with PVC hoops covered with plastic
• Plastic jugs or 2-liter pop bottles with bottoms removed
• Water-filled inner tubes
• Wall-O-Water, Season Starter, and Kozy Coat plant protectors
• Fiberglass panels arched over plants and held by stakes
• Burpee's Tomato Automators (red  or black plastic trays)

Buying tomato seeds

The local expert at your favorite garden center will know what varieties grow best in your vicinity. If you like to shop online my favorite source is Burpee Tomato Seeds because they have the largest selection of hybrid tomatoes and other plants including heirloom tomatoes and other garden vegetables.

90% Probability of Last Spring Frost - U.S. Cities

City	State	Avg Last Frost (90%)
Birmingham	Alabama	Apr 19
Mobile	Alabama	Mar 21
Anchorage	Alaska	May 19
Juneau	Alaska	May 24
Flagstaff	Arizona	Jun 23
Phoenix	Arizona	Feb. 9
Tucson	Arizona	Feb. 24
Fayetteville	Arkansas	Apr 25
Little Rock	Arkansas	Apr 9
Pine Bluff	Arkansas	Apr 3
Los Angeles	California	*
Sacramento	California	Mar 20
San Francisco	California	Jan 23
San Diego	California	*
Colorado Springs	Colorado	May 15
Denver	Colorado	May 13
Grand Junction	Colorado	May 9
Hartford	Connecticut	May 10
Wilmington	Delaware	Apr 21
Miami	Florida	Jan 16
Orlando	Florida	Mar 5
Jacksonville	Florida	Mar 21
Tampa	Florida	Feb 22
Atlanta	Georgia	Apr 14
Columbus	Georgia	Mar. 28
Dalton	Georgia	Apr 15
Honolulu	Hawaii	*
Boise	Idaho	May 8
Coeur d'Alene	Idaho	May 22
Kellog	Idaho	May 27
Carbondale	Illinois	Apr 29
Chicago	Illinois	May 6
Springfield	Illinois	Apr 25
Indianapolis	Indiana	May 4
South Bend	Indiana	May 11
Des Moines	Iowa	May 2
Mason City	Iowa	May 15
Kansas City	Kansas	Apr 21
Topeka	Kansas	Apr 21
Wichita	Kansas	Apr 21
Bowling Green	Kentucky	Apr 26
Louisville	Kentucky	Apr 21
Baton Rouge	Louisiana	Mar 19
Ruston	Louisiana	Apr 8
Bangor	Maine	May 23
Portland	Maine	May 15
Baltimore	Maryland	Apr 22
National Arboretum	Maryland	Apr 20
Boston	Massachusetts	Apr 21
New Bedford	Massachusetts	Apr 26
Dearborn	Michigan	May 17
Detroit	Michigan	May 10
Marquette	Michigan	May 26
Duluth	Minnesota	Jun 8
International Falls	Minnesota	Jun 8
Minneapolis	Minnesota	May 12
Gulfport	Mississippi	Mar 16
Jackson	Mississippi	Apr 8
Tupelo	Mississippi	Apr 22
Columbia	Missouri	Apr 21
Kansas City	Missouri	Apr 21
St. Louis	Missouri	Apr 19
Springfield	Missouri	Apr 29
Billings	Montana	May 17
Butte	Montana	Jul 7
Helena	Montana	Jun 4
Missoula	Montana	Jun 15
Lincoln	Nebraska	May 12
North Platte	Nebraska	May 23
Omaha	Nebraska	May 9
Las Vegas	Nevada	Mar 19
Reno	Nevada	Jun 13
Concord	New Hampshire	Jun 6
Nashua	New Hampshire	May 20
Atlantic City	New Jersey	May 10
Alamogordo	New Mexico	Apr 14
Albuquerque	New Mexico	May 3
Buffalo	New York	May 6
New York	New York	Apr 13
Fayetteville	North Carolina	Apr 13
Raleigh	North Carolina	Apr 25

City	State	Avg Last Frost (90%)
Bismarck	North Dakota	May 28
Fargo	North Dakota	May 21
Minot	North Dakota	May 22
Cincinnati	Ohio	Apr 27
Cleveland	Ohio	May 16
Columbus	Ohio	May 9
Dayton	Ohio	May 6
Lawton	Oklahoma	Apr 11
Oklahoma City	Oklahoma	Apr 13
Tulsa	Oklahoma	Apr 8
Bend	Oregon	Jul 14
Eugene	Oregon	May 24
Medford	Oregon	May 17
Ontario	Oregon	May 13
Portland	Oregon	Apr 15
Altoona	Pennsylvania	May 17
Philadelphia	Pennsylvania	Apr 19
Pittsburgh	Pennsylvania	May 10
Williamsport	Pennsylvania	May 13
Providence	Rhode Island	Apr 29
Charleston	South Carolina	Mar 8
Columbia	South Carolina	Apr 20
Aberdeen	South Dakota	May 20
Rapid City	South Dakota	May 25
Sioux Falls	South Dakota	May 19
Memphis	Tennessee	Apr 9
Nashville	Tennessee	Apr 21
Amarillo	Texas	May 1
Austin	Texas	Mar 15
Brownsville	Texas	Feb 13
Dallas	Texas	Mar 28
Houston	Texas	Mar 18
San Antonio	Texas	Mar 21
Logan	Utah	May 20
Salt Lake City	Utah	May 8
St. George	Utah	Apr 11
Burlington	Vermont	May 20
Rutland	Vermont	May 26
Richmond	Virginia	Apr 21
Roanoke	Virginia	Apr 27
Norfolk	Virginia	Apr 7
Chelan	Washington	Apr 25
Richland	Washington	Apr 21
Seattle	Washington	Apr 4
Spokane	Washington	May 18
Wenatchee	Washington	Apr 24
Green Bay	Wisconsin	May 12
Madison	Wisconsin	May 27
Milwaukee	Wisconsin	May 10
Charleston	West Virginia	May 8
Casper	Wyoming	May 22

* Frosts do not occur every year.

For even more U.S. cities visit the National Climatic Data Center or click here for average last frost dates in Canadian cities.

Planting your tomatoes outside no earlier than two weeks after the dates in the above table while being mindful of the best temperature conditions described above will set you up for an excellent start to the growing season!

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