Properties
- Improves aeration
- Increases moisture retention
- Excellent cation exchange properties
- Minimizes fertilizer leaching
- Has a near-neutral pH
- Inorganic and Sterile
Advantages of Vermiculite in plants
- Promotes early germination
- Plants survive longer in seasons of dry spells due to increase moisture retention
- For crops under irrigation, it means less water required per hectare, thereby saving on energy costs, machine wear and tear, and labor costs
- Improves oxygen supply to roots
- Excellent cation exchange properties result in high nutrient retention
- Improves yields
- Excellent for pest and disease control
How to use Vermiculite in Horticultural and Hydroponic Industry
Exfoliated vermiculite is an excellent growing medium and can be mixed with peat and/or pine bark. When used on its own it is necessary to add nutrients. Vermiculite has different grades and is packed in different quantities. It is important not to squash the vermiculite as the material is friable/easily crumbled. The air trapped between the laminae is important to the life of the plant. The word Hydroponics is derived from Greek meaning water and work. In hydroponic propagation, plants are grown in sterile growing media such as vermiculite.
CUTTINGS- Simply place cuttings (preferably treated with a growth hormone) into wet Vermiculite (exfoliated vermiculite). A mixture of Vermiculite/peat may also be used in the proportion 50.50 by volume. Place cuttings in semi-shade and mist over light each morning till the cuttings take.
SOIL CONDITIONER- Mix Vermiculite in roughly equal proportions with clay soil (by volume) in order to absorb the excess water. Similarly, equal parts of Vermiculite mixed with sandy soil will help to aerate the soil, stop compaction and it will improve both its water-holding capacities and its surface tension.
TYPICAL VERMICULITE GROWING MEDIA MIXES
Grain size (mm) Peat (%) Vermiculite (%) Application
1-3 0 100 Quick germination of fine seed
2-5 0 100 Quick germination of large seed
1-3 50 50 Slow germination of fine seed
2-5 25 75 Slow germination of large seed
2-5 50 50 Soft wood cuttings: on open bench
2-5 25 75 Soft wood cuttings: under plastic
2-5 75 25 Potting mix for house plants
0-5 60 40 Potting mix for vegetable plants
2-5 75 25 Potting mix for bedding plants
LAWN CONDITIONING- Fork/Spike the area well and then sprinkle vermiculite over the surface. Brush or water the vermiculite into the open areas. Alternatively, mix exfoliated vermiculite with lawn food before watering. Ideal for golf courses.
SEED SOWING- Sow seeds into pure Vermiculite or mix with peat/pine bark in seedling trays. Press seeds down firmly and cover with a layer of Vermiculite and mist (spray) with water daily. Seeds will germinate within a few days. It will however be necessary to add nutrients after a few days as Vermiculite is sterile.
Transfer of the seedlings into the growing beds will be easily accomplished as the roots will be protected with Vermiculite which will also act as an insulating and moisture-retaining medium.
POINTS TO REMEMBER
- Vermiculite is sterile so avoid contamination with dirty tools, infected soil, etc.
- Plastic and Polystyrene seedling trays should be cleaned by steam or with a mixture of bleach and water to kill bacteria from the previous growing season.
- Vermiculite is sterile and will therefore need to have nutrients added to the growing mixture.
- It is difficult to cover the requirements for all vegetables as well as flowers/seedlings but a mixture of 50:50 Vermiculite/peat is a good foundation once the seedling has germinated and grown to about 4 leaves in the seedling “plugs” (or the pure Vermiculite starting medium). The pH may be corrected to suit individual requirements.
