UNIVERSITY OF FLORIDA
Agricultural Experiment Station
IRISH POTATOES IN FLORIDA
A. P. SPENCER
Fig. 33-Spaulding's Rose 4.
The Station Bulletins will be sent free upon application to the Experiment
Station, Gainesville, Fla.
THa E. 0. PAINTER PRINTING Co., Da LAND, FL*ORmA
CO-OPERATIVE DEMONSTRATION WORK
A. A. MURPHREE, President State University
P. H. ROLFS, Director Extension Department
H. E. SAVELY, Agriculturist and Field Agent
C. K. MCQUARRIE. State Agent
A. P. SPENCER, District Agent for Central and South Florida
W. L. WATSON, District Agent for North and West Florida
BESSIE V. GLOVER, Secretary
J. M. SCOTT, Lecturer on Farm and Animal Industry
B. F. FLOYD, Lecturer on Citrus
J. R. WATSON, Lecturer on Insects
JOHN BELLING, Editor
1. A large area of Florida is suited to the growing of Irish potatoes.
2. The potato-growing sections of Florida are chiefly on flat-woods soil.
3. Soils intended for Irish potato growing require deep and thorough preparation.
4. Where the soil has a large supply of humus and is in good physical con-
dition, 15oo to 2000 pounds of fertilizer per acre may be economically applied.
5. Winter-planted potatoes require about 80 days to mature the tubers to a
6. Spaulding's Rose 4 is the favorite variety on flat-woods land.
7. In level artesian areas of Florida, surface irrigation from artesian wells can
be practiced economically.
Soils ------.. ---..--
Preparation of the Soil ----------
Planting --___- ___------------_-
Winter Planting ------
Fall Planting _------___----
Seed Potatoes ----------._------
Varieties ------_ ---.
Causes of Imperfect Stands ---
Irrigation --- ---------
. .-----------.-----------.---..------.-- 8
.---------------------- ----------- ----_ 86
----------------.--------. ----..-__ ..- 86
........ .._..... ..-__.. __. ._ 90
-------------- ---..--------------..____ 91
.----------------.____--------. __.___._ 9g
-...... .... ....-- ---- .- ...----. ____. 92
---------- _------------------ _____ 92
IRISH POTATOES IN FLORIDA
BY A. P. SPENCER
The Irish potato is sometimes called the white potato to dis-
tinguish it from the sweet potato. It has been grown in Florida for
nearly forty years in some sections. Until recently it has not been
considered a profitable crop for Florida except in very limited areas,
and then only on soils that were peculiarly suited to it. Unques-
tionably some soils are better adapted to this crop than others, nev-
ertheless it is certain that a large area of Florida, much of which
until recently was considered unsuitable, is in fact suited to the
growing of Irish potatoes. Irish potatoes grow best in soils well
filled with humus, where there is ample moisture, and where the
surface water can be controlled.
The Irish potato growing sections of Florida are chiefly on flat-
woods soils. Most of these soils are underlaid with hardpan,
which in places lies close to the surface, and in other places is at a
varying depth. Where this hardpan lies close to the surface it
is advisable to break it up by subsoiling, or by the use of dynamite;
but when it lies from three and a half to five feet below the sur-
face, it is a decided advantage by holding close to the plant much
irrigation water that would otherwise drain away.
Many of these soils have little humus when first broken, but
by the system of rotation usually practiced, large amounts of veg-
etable matter are turned under each year. This rapidly increases
the humus content of the soil, until a first-class potato-growing
soil results. It is important that flat-woods soils should have good
Low hammock land also makes a good soil for Irish potatoes,
because of the amount of humus and its capacity to hold water.
The drainage in such lands does not usually interfere with the
crop, but in times of continued drouth irrigation may be neces-
High pine lands are less suitable for Irish potatoes than the
flat-woods or hammock, because of the lack of humus, and fre-
Florida Agricultural Experiment Station
quently the lack of moisture when the crop.is growing. Where
high pine lands can be supplied with humus and irrigated, they can
be made to produce profitable crops of Irish potatoes; especially if
underlaid with clay.
Scrub oak lands are not suitable for growing Irish potatoes.
Their dry sandy character, and lack of humus make them unprof-
itable for this.
PREPARATION OF THE SOIL
All soils intended for Irish potato growing require deep and
thorough preparation. Depth of soil is most important because of
the moisture requirements of the crop. The soil must be thor-
oughly pulverized, and made open and loamy. Frequent cultiva-
tion before the crop is planted is necessary to secure a full stand and
an abundant setting of tubers. Soils of a close and compact nature
should be improved by turning under a green crop and allowing it
to decay before the land is planted. While the Irish potato does
best on a moist soil, it is not possible to get an even stand or a
good crop where the water stands for a week or ten days after
heavy rains. New lands that have not been cultivated or planted
before, will be improved by planting with sweet potatoes the first
year, with velvet beans or cow peas plowed under the second year.
and with Irish potatoes the third year. These two crops should
prepare the soil well for the Irish potatoes, providing it is naturally
The Irish potato requires a complete fertilizer on most Florida
soils. In the flat-woods section growers get good results from a
formula analyzing approximately 4 per cent. of ammonia, 7 per
cent. of phosphoric acid, and 8 per cent. of potash. The material
necessary for a ton may be made as follows:
o155 pounds cottonseed meal,
655 pounds 16 per cent. acid phosphate.
290 pounds sulphate of potash,
800 pounds blood and bone,
900 pounds 16 per cent. acid phosphate,
300 pounds sulphate of potash.
This mixture would be suitable for hammock lands, but for high
pine lands where the humus is deficient the ammonia should be in-
creased to five or six per cent. The amount to be applied will de-
pend upon the conditions of the soil. Where the soil has a large
supply of humus and is in good physical condition, 1500 to 2000
pounds to the acre may be economically applied; but on newer
lands, where the depth of the soil is less than eight inches, from
iooo to 1200 pounds will be about the maximum amount that can
be profitably used. The most successful potato growers in Florida
have made it a regular practice to turn under large quantities of
crab grass, beggarweed, and other vegetable growth. This supplies
the soil with humus and improves its physical condition, and so
ensures a heavier yield. Stable manure is not generally used as a
fertilizer for Irish potatoes, but when applied at the rate of five
to ten tons per acre it will give good results. All vegetable growth
Pin.-- 4,4- !
Fig. 34-Showing high ridges and beds, with water furrows
between the beds.
Florida Agricultural Experiment Station
or stable manure should be plowed under one month or more be-
fore the date of planting. Commercial fertilizer may be applied
immediately before the seed potatoes are placed in the ground.
Most growers prefer to apply this broadcast. Just before planting
the soil should be thoroughly pulverized with a disc harrow, and
the fertilizer applied and mixed thoroughly with the soil. Then
the beds in which to plant the seed are made
On flat-woods land, when the seed-bed is prepared, the land
should be ridged 15 or 18 inches high, or sufficiently to
give drainage to the beds. On high hammock or high pine land
the cultivation may be almost flat, although most growers prefer to
plant the seed potatoes on a low ridge about eight inches high.
The rows may be set 3 feet apart, and one seed dropped every 15 or
18 inches. If the land is not in the best state of cultivation it will be
better to have the rows 4 feet apart. The seed should be covered
4 to six inches deep.
The greatest acreage of Irish potatoes in Florida is winter
planted. From Tampa southward, planting should be done be-
tween December 15 and January 15; between Gainesville and
Tampa, from January 15 to February 20; and in sections north
and west of Gainesville from February I to March o1. The Irish
potato plant will withstand a light frost but not a freezing tem-
perature, so that it is well to avoid too early planting for the spring
crop in the northern parts of Florida because of the freezing tem-
perature that may occur up to March I. It requires about 80 days
from planting to mature the tuber to a marketable size. If the vines
are well grown, a freeze will destroy the crop; but if they are just
putting out their first leaves and getting most of their nourishment
from the tuber, they will sprout up again in case they are frozen
off, and the injury will be slight.
The fall-planted Irish-potato crop is not so important from a
commercial standpoint as the winter plantings. The produce of
nearly all fall-planted Irish potatoes is consumed locally, hardly any
being shipped to northern markets. There is, however, usually a good
local demand at a fair price in southern markets; so that if one has a
soil suitable for a fall crop of Irish potatoes it is advisable to grow
them to supply the local trade.
In central and west Florida, planting should be done not later
than September I, and in southern Florida by September 15. This
will permit the crop to come off by Christmas, when the land may be
planted to winter vegetables.
There is hardly any difference in the method of preparation and
fertilization of the soil, except that the rows should be not less than
four feet apart, and the seed potatoes dropped eighteen to twenty
inches in the rows. The probability of less moisture in the soil dur-
ing the fall because of the higher average temperature during Sep-
tember and October than during the growing season of the winter
crop, makes it necessary to give fall plantings more distance in the
rows: furthermore, soils that are naturally drier are less suitable
for fall planting than for winter planting.
Florida Agricultural Experiment Station
In extreme South Florida a considerable acreage is planted in
the fall to produce "new potatoes" for midwinter markets. The
plantings are generally treated about like those intended for a
Growers should exercise special care in the excellence and purity
of strain of their seed potatoes. Aside from the possibility of intro-
ducing diseases, the nature of the seed potatoes determines to a
large extent the productiveness of the crop. Seed potatoes should
be secured from responsible growers or seedsmen. Seed from an in-
ferior crop is most likely to give a low yield and produce tubers of
a second grade. Florida-grown seed potatoes are not generally used
for winter planting. Most of the seed is purchased from Maine.
For fall planting when the seed is taken from the spring-grown crop
it should be kept over summer spread out in a dry place. By plant-
ing only sprouted tubers a fair stand is usually obtained.
The most successful growers select their best potatoes for seed,
and cut them to two well-matured eyes in each piece. Where the
tubers are large, and to be planted in three and one-half foot rows,
about twelve bushels per acre will be required for seeding. Where
the seed potatoes are of moderate size, ten bushels per acre is con-
sidered good seeding. When the seed is to be cut, it is best to have
it done a few days before planting. Mix a little lime through the
pile. The lime has a preserving effect on the cut surfaces.
The varieties that have given best results in Florida are:
Spaulding's Rose 4, Bliss Triumph, Lookout Mountain and
Irish Cobbler. Spaulding's Rose 4 has been the favorite on
flat-woods land. It grows rapidly, is a good shipper, is well estab-
lished in the markets, and is most generally recommended.
CAUSES OF IMPERFECT STAND
Where a stand is imperfect it is impossible to get the maximum
yield even though all other conditions may be the best. There is
always a heavy cost in preparing the land for planting, and purchas-
ing the seed and fertilizer; so that the cost up to harvesting is nearly
the same for a poor stand as for a full stand. An imperfect stand
Fig. 36-Bliss Triumph.
may be due to planting immature or diseased seed, too deep plant-
ing on soils with poor drainage, too shallow planting where there
is insufficient moisture, or planting the seed in land that has not been
thoroughly prepared. One must avoid these unfavorable condi-
tions in order to make Irish potato growing profitable under the
expensive cultural methods usually practiced in Florida.
Irish potatoes require frequent cultivation. If the weather is
unusually dry frequent cultivation is most important to conserve
the moisture. When the rainfall is plentiful, especially on soils that
have a tendency to become compact, frequent cultivation is necessary
to keep the soil in a loose condition and to hasten the growth. Grass
or weeds growing in the rows take both moisture and fertilizer,
and must be kept down. When the crop is planted in high ridges
a V-shaped cultivator that will stir the bottom of the furrow and
the sides of the banks does the best work. Where the ridges are
not so high, an ordinary cultivator will serve the purpose; and in
Florida Agricultural Experiment Station
the event of heavy rains the dirt may be thrown back to the banks
with a plow.
Many potato-growers prefer to use the disk cultivator. This
helps to keep the rows ridged up. The inner disks are set higher
than the outer ones, very much as is done for making the ridges.
For marketing, it is not necessary that the Irish potato should
be thoroughly ripened. When the crop has reached a marketable
size, and the skin slips on pressure of the thumb, the potatoes are
ready to dig; but where the tubers are to be used for seed, they
should be allowed to remain until about mature. If the crop has
had no setbacks, it should be ready to dig at from seventy to
eighty days after planting. The tops usually die down in from
ninety to ninety-five days, and the growth of the tuber nearly stops.
Where several acres are planted, it will pay to use a potato-digger.
In small areas it may be best to dig with hand tools.
There is usually a good market for the spring crop of Florida-
grown Irish potatoes because of the shortage of new potatoes on
the markets during April and May. To reach this market economi-
cally, the potatoes must be properly barreled and graded, and
shipped in carload lots. Seventy-five barrels per acre is considered
a heavy yield.
An average yield should be about forty barrels per acre.
In all sections of Florida, Irish potatoes can be used in a rotation
of crops. In the potato-growing sections it is a common practice to
plant during January, and the potatoes are ready to dig about April.
Immediately after the last cultivation corn is planted, and the dig-
ging of the potatoes is the first cultivation the corn gets. The corn
is mature about July 20, when cowpeas are planted between the rows,
giving a third crop off the land. Where cowpeas are not grown, the
land usually grows up in crabgrass, which is cut off for hay or turned
under to form humus. Such a rotation gives a variety of crops and
keeps the land in a good physical condition. This same land is
again set in Irish potatoes the following winter, but it would be
better if Irish potatoes were followed with a different crop the fol-
As Irish potatoes grow best in a cool soil holding plenty of
moisture, irrigation will go a long way toward ensuring a profitable
yield when the rainfall is only average or below. When rains are
frequent and the soil is deeply prepared and in a good physical con-
dition, irrigation will not be necessary on low hammock or flat-
woods land. On high hammock, rolling pine lands, or even in
drained-out muck ponds or lake bottoms an irrigation system will
be a great help to ensure a satisfactory yield almost every year.
In unusually dry seasons there is a great possibility of failure in
nearly all Florida soils without some artificial system to supply water
to the crop, as the tubers will stop growing unless they have suffi-
In the artesian areas of Florida where the land is level, surface
irrigation from artesian wells can be practiced economically; but
when the water must be pumped into a reservoir and then piped
into the field, the cost of installing is greater, and the cost of ap-
plying the water is so increased that the advisability of installing
such a system for Irish potato growing alone is questionable.