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W* i Woodchip Sewage Sludge Compost as an Ingredient. .
qo- of Potting Mixtures for Foliage Plants I-,
R.T. Poole and C.A. Conover 1i
University of Florida, IFAS /
Central Florida Research and Education Center Apopka 7
CFREC-Apopka Research Report RH-90-4 of ...
Some foliage plants have specific potting medium requirements, but
most grow well in a variety of potting mixtures, and thus, there is no
single best growing medium for foliage plants. High quality potting
media produce quality plants, in the shortest time, with the lowest
total production costs. Potting medium components should be readily
available to growers, inexpensive, uniform, and sterile.
Most potting mixtures are blends of two or more materials. Good
quality sphagnum peat moss or sedge peat moss, vermiculite, builders'
sand, and pine bark are four popular ingredients used today.
Unfortunately, these, and other popular potting medium amendments are
becoming more costly and less readily available to the foliage plant
industry. Growers are looking for less expensive potting medium
amendments to replace, in part, the more expensive ingredients in their
mixes. They want more information on new potting medium amendments
because any amendment added to a potting medium will affect its physical
characteristics and plant growth.
Compro, a woodchip sewage sludge compost, manufactured by Maryland
Environmental Service, 60 West Street, Annapolis, Maryland, was shown to
be a satisfactory ingredient of potting media in a preliminary
experiment. Compro is produced by mixing sewage sludge with woodchips,
then composting this mixture at temperatures well into the
pasteurization range, up to 1800F. The compost-woodchip mixture is then
screened to eliminate large woodchips. Compro has a pH of 6.8-7.4. The
composted sludge is dense, with a dry weight of 40 lb/ft and has a
water-holding capacity of 225% by weight. Two experiments were
conducted to determine growth of 4 foliage plants in various potting
media with different levels of Compro incorporated. The physical
characteristics of these media were also determined. These media
physical characteristics have already been published (Proc. Fla. State
Hort. Soc. 98:92-94, 1985) and will not be mentioned here.
Experiment 1, initiated June 24 utilized 3 base potting media which
were (1) 3 Florida peat:l builders' sand; (2) 2 Florida peat:l pine
bark:l cypress shavings; and (3) 1 Florida peat:l pine bark. Five
levels of woodchip sludge compost were added to make up 0, 10, 20, 30,
or 40% of the above media. The resulting 15 potting mixes were amended
with 1.5 lb/yd3 Micromax and 7 lbs/yd dolomite. Micromax is a
micronutrient blend manufactured by Sierra Chemical Co., Milpitas, CA.
These mixes were then used to grow rooted cuttings of Dieffenbachia
maculata dieffenbachiaa) and Peperomia obtusifolia (oval-leaved
peperomia) in 6 inch standard pots.
S1IProfessor, Plant Physiology and Center Director and Professor,
respectively, Central Florida Research and Education Center, 2807
Binion Road, Apopka, Florida 32703.
Osmocote 19-6-12, manufactured by Sierra Chemical Co., Milpitas, CA, was
surface applied at 2 grams per pot for Peperomia and 3.3 grams per pot
for Dieffenbachia, on June 24 and Sept 26. Plants were grown in a
greenhouse receiving 1500 ft-c maximum light and temperatures ranging
from 65 to 95F. Plants were irrigated 2 or 3 times weekly. On Oct
24, experiment 1 was terminated and the following data were determined:
plant height, plant quality, rated on a 1 (poor, not salable) to 5
(excellent quality) scale; and root grade rated on a 1 (0-20% root ball
coverage) to 5 (81-100% root ball coverage) scale.
Experiment 2 soil treatments were the same as those in experiment 1.
Brassaia actinophylla (schefflera) and Chrysalidocarpus lutescens
(areca palm) were placed in 8 inch pots on July 9 and fertilized with
9.5 grams and 7.0 grams respectively, of 19-6-12 Osmocote on July 9 and
Oct 14. Plants were grown in a shadehouse receiving 6,000 ft-c maximum
light with temperatures ranging from 50 to 980F. Growth data for
Brassaia were taken on Dec 8; for Chrysalidocarpus on Feb 8. Plant
height and quality were determined as well as foliar color grade rated
on a 1 (light green) to 5 (dark green) scale.
Dieffenbachia and Peperomia grown in 3 Florida peat:1 builders' sand
(base medium) were slightly taller and of higher quality than plants
grown in the 2 other base media, but root grade was reduced (Table 1).
Brassaia and Chrysalidocarpus grew equally in the 3 base media (data
not shown). Additions of Compro to these 3 base potting media had no
influence on the height or quality of plants grown. Allplants grown
were of good salable quality. These experiments demonstrate that media
composed of 10 to 40% Compro can be used without reducing quality of
the plants tested.
1. Chase, A. R. and R. T. Poole. 1985. Root Rot. Greenhouse Manager
4(2):142, 145, 146, 149.
2. Conover, C. A. and R. T. Poole. 1978. Influence of Florida humate
on foliage plant growth. Proc. Soil and Crop Sci. Soc. Fla. 38:5-7.
3. Fonteno, W. C., D. K. Cassel, and R. A. Larson. 1981. Physical
properties of 3 container media and their effect on poinsettia
growth. J. Amer. Soc. Hort. Sci. 106:736-741.
4. Joiner, J. N. and C. A. Conover. 1965. Characteristics affecting
desirability of various media components for production of
container-grown plants. Proc. Soil and Crop. Sci. Soc. Fla.
5. Poole, R. T. and C. A. Conover. 1977. Influence of medium,
container size and water regime on growth of Pellionia pulchra N. E.
Br. and Pilea involucrata (SIMS) URB. Proc. Fla. State Hort. Soc.
6. Poole, R. T., C. A. Conover, and J. N. Joiner. 1981. Soils and
potting mixtures, p. 179-202. In: J. N. Joiner (ed.). Foliage plant
production. Prentice-Hall, Inc., Englewood Cliffs, N.J.
Table 1. Response of foliage plants grown in various potting media,
June 24 to Oct 27.
Dieffenbachia 'Camille' Peperomia obtusifolia
Plant Plant Root Plant Plant Root
Potting media ht (in) grade gradeY ht (in) grade gradey
3.1x 16 5.0 4.4 11 4.4 4.0
2:1:1 15 4.7 4.3 9 3.9 4.2
1:1 14 4.6 4.6 10 4.1 4.3
zi = poor, not salable, 5 = excellent quality.
Yl = 0-20% root ball coverage, 5 = 81-100% coverage.
x3 Florida peat:l builders' sand; 2 Florida peat:l cypress shavings:1 pine
bark; 1 Florida peat:l pine bark.