SCHEDULING SWEET CORN PLANTINGS
THE EASY WAY
by using plant maturity

Developed by Hank Bissell of Lewis Creek Farm in Starksboro Vermont
With a grant from the Vermont Vegetable and Berry Growers' Association

Lewis Creek Farm

Sustainable Agriculture at Lewis Creek Farm

Farm Employment
at Lewis Creek
Farm

YOU KNOW THE PROBLEM
If you grow sweet corn commercially, you know that one of the biggest problems with sweet corn growing and marketing is when several plantings "Bunch up" and are all ready at the same time. At times like this you have too much corn for your regular markets and you drop your price to try to move more volume, most often to no avail. You probably didnít sell all your corn, and you probably took a rotten price for it. Talk about adding insult to injury.

Avoid having your sweet
corn "all ripen at once".
Let the maturity of the
corn you've already planted
tell you when to make your
next planting.

Vermont Vegetable and Berry Growers' Association YOUíVE HEARD OF THE SOLUTION
If youíve been growing sweet corn for very long, youíve
probably heard about scheduling sweet corn plantings using
growing degree days, and that itís alleged to solve the problem
of plantings bunching up.

BUT YOUíRE NOT USING IT
You may even have heard a presentation or read an article
about how to apply this method on your own farm. But for
some reasonÖ youíre not using itÖand I would guess that is
because it sounds a bit like you need a team of NASA scientist
to collect data and execute the daily calculations of transpired
growing degree days since your last planting of corn
smallfield

HEREíS AN EASIER METHOD
Well, it doesnít have to be that hard. I have developed a method of measuring transpired growing degree days that is very easy to use. It is based on the premise that the corn plants themselves develope in proportion to the number of transpired growing degree day. So, if you know how many transpired growing degree days you are waiting for until you plant your next planting, and you know what a corn plant looks like when that number of growing degree days has passed, then, by looking at the corn plants, you can tell when to make your next planting.

STEP ONE
How many varieties or you using in a planting group?
Some growers only plant one variety over and over again. Many growers, however, use variety groups to help schedule their plantings. For instance I use Mystique - 75 days, then Precious Gem -78 days, then Delectable - 82 days and I repeat this group of varieties over and over through out the planting season. So, Iím using 3 varieties in my planting group.

STEP TWO
How many "days to harvest" are there between the first and last variety in you planting group?
If you are growing only one variety the answer is zero, and if you are growing the three varieties that I use the answer is seven (82-75=7).

STEP THREE
Look up the plant maturity on the table below.
On the right side of the table, look up the differnce in days to harvest from step two, then go across until you come to the column that corresponds to the number of varieties in your planting group. You will find an answer in Growing degree days (GDD).Remember the number and click on the link. This will take you to a photograph of a sweet corn plant that has accumulated that number of growing degree days. This is the growth stage you will wait for before making your next planting.


The chart below will link you to a series of photographs which make up a "Plant Maturity Scale". You can use this scale to determine when you should seed your next planting of sweet corn. By using this method you will avoid having several plantings all ripen at once. See steps one, two and three above to use this chart correctly.

Difference
in days
to harvest
1 Variety
per planting group
2 Varieties
per planting group
3 varieties
per planting group
4 varieties
per planting group
0
Not Possible
Not Possible
Not Possible
1
Not Possible
The 2 varieties you have chosen
are too close together just use 1 variety
The 3 varieties you have chosen
are too close together just use 1 variety
The 4 varieties you have chosen
are too close together just use 1 variety
2
Not Possible
The 2 varieties you have chosen
are too close together just use 1 variety
The 3 varieties you have chosen
are too close together just use 1 variety
The 4 varieties you have chosen
are too close together just use 1 variety
3
Not Possible
The 2 varieties you have chosen
are too close together just use 1 variety
The 3 varieties you have chosen
are too close together just use 1 variety
The 4 varieties you have chosen
are too close together just use 1 variety
4
1 variety replanted so there
are 4 harvest days beween
plantings

108 GDD
The 3 varieties you have chosen
are too close together just use 2 varieties
The 4 varieties you have chosen
are too close together just use 2 variety
5
1 variety replanted so there
are 5 harvest days beween
plantings 80GDD

121 GDD

The 3 varieties you have chosen
are too close together just use 2 varieties
The 4 varieties you have chosen
are too close together just use 2 variety
6
1 variety replanted so there
are 6 harvest days beween
plantings 108 GDD

147 GDD

136 GDD
The 4 varieties you have chosen
are too close together just use 3 variety
7
1 variety replanted so there
are 7 harvest days beween
plantings 121 GDD

172 GDD

161 GDD
The 4 varieties you have chosen
are too close together just use 3 variety
8
1 variety replanted so there
are 8 harvest days beween
plantings 136 GDD

199 GDD

172 GDD

190 GDD
9
1 variety replanted so there
are 9 harvest days beween
plantings 147 GDD

215 GDD

240 GDD
no photo available

199GDD
10
1 variety replanted so there
are 10 harvest days beween
plantings 172 GDD

255 GDD
No photo available

227 GDD
No photo available

215 GDD


BASIC PROCEDURE:
1) You plant your first planting of the variety group.
2) Watch the plants in that planting. You're looking for the "early majority" of the plants in that planting to reach the specified growth stage.
3) When your first planting has reached the specified growth stage, itís time for you next planting.
4) Continue with the same procedure for subsequent plantings.

BE PATIENT IN MAY
You will find that early plantings in May (cool weather) are exasperatingly far apart and that plantings in June (Hot weather) are alarmingly close together. Relax, thatís the way itís supposed to be.

NOTE 1
Once you've found the photo showing the stage of maturity that will tell you it's time to make your next planting, take a good look at the photos and descriptions of the stages that come before it. This will help you reccognize the subtile differences in maturity, and help you anticipate the stage that you're waiting for. Those of us who have used the system much have come to realize that it's hard to find out that today is the day to make your next planting of corn, and to actually get it done today as well.

NOTE 2
Plantings after June 25
Plantings seeded after June 25 most likely ripen after Labor Day. In a very cool year they might not even beat the first frost in September. Proceed with caution.

NOTE 3
Growing degree days after September 1 accumulate more slowly.
Plantings seeded after June 25 can be harvested over a longer period of time, because the GDD in September accumulate increasingly slowly. in addition, in most situations demand is lower as well after Labor Day, so plan accordingly.

NOTE 4
Plantings seeded after July 4th will not ripen before the first frost.

NOTE 5
All this talk about dates and fall frosts is for Starksboro Vermont where the last spring frost is about May 20 and the first fall frost is about September 27.