Overview:
We compared four techniques for growing melons in order to
determine the best yield in terms of numbers, quantity and quality of the
fruit. As an adjunct, one of the methods included a trellis configuration in
order to determine the feasibility of vertical growth for Santa Clara residents
who do not have access to space required to grow melons in the traditional
manner. The four methods were:
- Heat sink
- The idea behind this method was to surround the plant with a medium
that would absorb heat in the day and release heat to the soil during the
night. In this case the medium were ordinary fireplace bricks.
- Black
plastic - Consisted of a strip of black plastic covering the row of melons.
The strip was approximately 24 feet long and 3 feet wide. Purpose was to trap
solar energy to heat the soil.
- Control
plot - Melon plants were planted directly into the soil.
- Trellis
plot - Trellis was constructed out of 5-foot high concrete reinforced
mesh wire and secured with rebar or stakes.
Melon plot, from left to right: trellis, control, black plastic, heat sink
Close-up of heat sink brick arrangement
Team members:
Mary Collins, Suna Herder, Dan Johnston, Joan Kendig, Karen
Schaffer
Soil preparation:
On May 12th a 24-foot square plot at Nine Palms was spread
with approximately 6 inches of Garrod's horse compost and rototilled.
Four
rows, 4 feet wide were raised and separated by 3-foot paths. Each row was 24
feet long and 3 feet wide. The rows were oriented approximately northwest to
southeast.
Seeding/planting:
Seeding was started approximately May 1 in four-inch pots
and consisted of two melon varieties: Ambrosia cantaloupe and French Orange, a
Charentais hybrid. Seeds for both were from Park Seeds.
Four seeds of each variety were planted in 40 pots (20
Ambrosia, 20 French Orange Charentais) and thinned to strongest three at
planting. Each row was started with a French Orange and alternated with an
Ambrosia. Each row had four French Orange and four Ambrosia consisting of three
plants per hill. 48 Ambrosia and 48 French Orange were planted
in the four rows. Planting was conducted on June 4th with each three plants
receiving a handful of alfalfa pellets in the bottom of each hole.
Watering:
Watering was conducted Mondays, Thursdays and Sundays on an
automatic drip system for 45 minutes each day.
Fertilization and
pesticides:
Other than mentioned above, no other fertilizers were
applied after planting. No pesticides were applied.
Harvesting:
Harvesting was started Tuesday the 8th of August and
continued every Tuesday and Thursday until the 29th of September.
Harvesting
was discontinued when plant growth declined and melon quantity and quality also
declined significantly. Harvesting totaled 16 days during the 8-week growing
period.
On the left is an Ambrosia melon, on the right is a French Orange Charentais melon.
The Ambrosia is a particularly large example, but the Charentais is average.
Observations:
Table 1 show the total production for each method and
variety. The black plastic method yielded the most melons. The heat sink and
control had similar results. The trellis method produced the least, yet still
quite respectably, and the melons were the largest on average.
|
Heat sink |
Black Plastic |
Control |
Trellis |
|
Ambr. |
French Orange |
Ambr. |
French Orange |
Ambr.
| French Orange |
Ambr. |
French Orange |
Total weight |
74.54 |
53.9 |
113.3 |
53.17 |
79.4 |
45.23 |
70.01 |
46.1 |
Total melons harvested |
30 |
41 |
41 |
35 |
31 |
34 |
23 |
26 |
Average melon weight |
2.48 |
1.31 |
2.76 |
1.51 |
2.56 |
1.33 |
3.04 |
1.77 |
Table 1: Grand Totals, from 8/8/06 to 9/29/06
Chart A shows the weekly production for Ambrosias and chart
B the weekly production for French Orange Charentais. Notice that the black
plastic method produced most of its melons in the first three weeks.
The
trellis method produced more modestly, but at a more even rate throughout the
season.
Chart A
Chart B
Black plastic achieved 50% (84 lbs) of total productivity
approximately August 18th or two weeks into the growing period.
The heat sink
plot achieved 50% (66 lbs.) of total of total productivity approximately August
25th or 3 weeks into the growing period. Control plot reached 52% (62 lbs.) of
total productivity in the same time as the heat sink. Trellis reached 50% (57
lbs.) of total productivity approximately September 1st or 4 weeks into the
growing period.
Comments:
It is surmised that soil temperature is the single-most
factor responsible for total yield, growth, and maturity rates.
Soil
temperatures were taken through the month of July, 5 measurements each bed.
Temperatures were measured between 9 and 10 a.m.
Average July soil temperatures
were as follows:
- Heat sink: 79 degrees.
- Black plastic: 81 (85-90) degrees*
- Control: 79 degrees
- Trellis: 79 degrees
*Black plastic temperatures were measured several inches
from the plants in uncovered soil. However, temperatures under the plastic were
consistently four to nine degrees higher.
Pests and Disease:
A small percentage of melons were lost due to rats or
gophers. No diseases were observed that affected the growth or maturity of any
melon plants.
Summary:
The most productive technique in this project was the black
plastic method. Clearly, the black plastic provided the necessary medium to
raise soil temperatures, trap and retain heat during night-time cooling.
Additionally, although it cannot be independently confirmed, black plastic may
have contributed significantly to moisture retention affecting overall yield.
On a slightly negative the black plastic matured at a rapid rate (2 weeks) and
did not provide a consistent flow of fruit throughout the 8-week growing
period. This is indicated in the attached charts.
The second best method as far as production was the control
plot. In all aspects it was equal to the heat-sink method in terms of average
total yield and maturity rates. It is recommended for those gardeners who have
the space and prefer a no-fuss melon patch.
The third recommended method is the trellis.
Although it was
not the most productive in terms of gross yield, it was the most consistent in
providing fruits on a regular basis without a drop in production unlike the
black plastic method. It is highly recommended for gardeners with limited
gardening space who desire a consistent supply of fruit during the growing
period.
The fourth method (the heat sink) is not recommended due to
the work involved, brick expense, labor and preparation of the plot.
In
retrospect and in consultation with a mason expert, it was recommended that a
better medium would have been concrete cinder blocks as they heat faster and
release heat faster due to the fact that they are less dense. Bricks on the
other hand are denser requiring a higher temperature heat and are slower to
release heat into the soil. This method may warrant a second trial but then
again the black plastic for now is "king."
Dan with melons
Revised: 05-Jan-2007
