Horticulture Principles and Practices

TABLE 4–11
Selected Standard Mixes
1. Cornell Peat-Lite Mix A Quantity
Materials Per Cubic Yard Per Cubic Meter
Sphagnum peat moss 0.5 yd 3 0.5 m 3
Vermiculite 0.5 yd 3 0.5 m 3
Ground dolomitic limestone 5 lb 3 kg
Single superphosphate 1–2 lb 0.6–1.2 kg
Calcium of potassium nitrate 1 lb 0.6 kg
Fritted trace elements 2 oz 74 g
Wetting agent 3 oz 111 g
2. Cornell Peat-Lite Mix B
Substitute horticultural perlite for vermiculite
3. The University of California Mix
Quantity
Materials Per Cubic Yard (lb) Per Cubic Meter
(kg)
Hoof and horn or blood meal (13%) 2.5 1.47
Potassium nitrate 0.25 0.15
Potassium sulfate 0.25 0.15
Single superphosphate 2.5 1.47
Dolomitic lime 7.5 4.42
Calcium carbonate 2.5 1.47
The University of California Mix, as constituted above, should be used fresh; if storage is needed, the mix should exclude
the hoof and horn or blood meal.
2. Good drainage and aeration. The mix should be well drained to reduce the
danger of overwatering, which can cause a perched water table. Most plant roots
are intolerant of anaerobic conditions. Materials such as perlite and sand are
used for good aeration. Good soil drainage guards against the buildup of harmful
salts.
3. Proper pH. Improper soil reaction interferes with nutrient availability for
plants. Certain organic materials used in mixes produce acidity or alkalinity in
the medium. The use of lime is necessary to correct soil acidity.
4. Fertility. Most soil mix ingredients do not contribute appreciably to the fertility of
the growing medium. Additional materials such as fertilizers are needed to provide
the required nutrition for proper plant growth and development.
Advantages of Soilless Mixes
The major advantages of soilless mixes include the following:
1. Uniformity of mix. The physical and chemical properties of a mix are uniform
throughout the mix, a condition not found in field soil. The homogeneity of the
medium makes it possible for plants to grow and develop uniformly, provided
other growth factors are also consistent.
2. Ease of handling. Mixes are lightweight and easy to transport. Ingredients are
easy to scoop and move around during manual preparation.
3. Versatility. Mixes can be made to order (custom mixed) for specific needs; can
be used to amend soils in the field by mixing into flower beds, lawns, or garden
soil; and are convenient to use in container plants.
4.10 Potting Media 147