Potting soil for Delphinums

Officers – Plant Care – Potting
How to plant

Potting Compost

additional potting information is located on the left

John Innes Potting Compost

Seed compost:

2 parts sterilised loam
1 part moss peat
1 part sharp sand

The loam and peat is put through in 3/8
in (9mm) sieve.

To each bushel (8gal/36l) is added:

1.5 oz (42gm) superphosphate
3/5 oz (21gm) ground limestone

Potting Compost:

7 parts sterilised loam
3 parts moss peat
2 parts sharp sand

The loam and peat is put through a 3/8
in (9mm) sieve.
To each bushel (8gal/36l) is added

3/4oz (21gm) ground limestone
4oz (110gm) 14-14-14 Osmocote

This makes John Innes Potting Compost
No. 1.
For a richer mix simply double the quantity of
John Innes Base to make No. 2 or treble it to
make No.3


From Hobby Greenhouses in Alberta

Agdex 731-5

The Cornell peat-Lite Mix* is formulated
for growing topical plants. The Foliage Plant Mix **
and the Epiphytic Mix** formulas are adapted specifically
for their respective plant types and are modifications
of the original peat-lite mix.

Cornell has used Osmocote 14-14-14 and
Peters 14-7-7 fertilizers with the tropical plant mixes
with good results. Other fertilizers are omitted with
the exception of dolomitic limestone and 20 per cent
superphosphate which are added to adjust the pH and
to maintain adequate phosphorus levels. A trace element
mix is added to assure a balance of minor elements.
Trace element mixes can be purchased from specialty
gardening centers.

* “Cornell Tropical Plant Mixes”
by Russel C. Mott

**L.H. Bailey Hortorium, Cornell University,
Ithaca, New York

Cornell Peat-lite Mix

Mix 1/2 cubic meter each of sphagnum peat
moss and perlite or vermiculite. Add 6kg dolomitic limestone,
2.4 kg ammonium nitrate, 1.5 kg superphoshate, and 0.3
kg potassium chloride (omit if using vermiculite).

Cornell Foliage Plant Mix

The Cornell Foliage Plant Mix was developed
for those plant that need a growing medium with high
moisture-retention characteristics. Plants having a
fine root system or possessing many fine root hairs
are included in this group.

Material 1 cubic meter
Sphagnum peat moss (screened 1/2 inch
Horticultural vermiculite (No. 2) 0.25
Perlite (medium grade) 0.25
Ground dolomitic limestone 4.9 kg
Superphosphate 20% (powdered) 1.2 kg
Fertilizer (10-10-10) 1.6 kg
Iron sulfate 0.4 kg
Potassium nitrate (14-0-44) 0.6 kg
Granular wetting agent 0.9 kg

Cornell Epiphytic Mix

The Cornell Epiphytic Mix was developed
for plants that require good drainage, aeration and
have the ability to withstand drying between warterings.
Plants having coarse, tuberous, or rhizomatous roots
are in this category.

Material 1 cubic meter
Sphagnum peat moss (screened 1/2 inch
Douglas, red or white fir bark* (about
0.5 cm size)
Perlite (medium grade) 0.25
Ground dolomitic limestone 4.2 kg
Superphosphate 20% (powdered) 2.7 kg
Fertilizer (10-10-10) 1.5 kg
Iron sulfate 0.3 kg
Potassium nitrate (14-0-44) 0.5 kg
Granular wetting agent 0.9 kg

* Fir bark comes from Douglas fir, white
or red fir, or redwood, ground and screened to a definite
size. Finally ground bark (about 0.5 cm) has a dry weight
of about 200 g per liter cube. Fresh bark has a pH of
about 5.0. Upon weathering, it becomes slightly more
alkaline. The bark contains some nutrients, but these
will not meet the requirements of growing plants.


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