Hey, hoping you are having a good time with your family this festive season even as you look forward to the new year. I received a complaint from one of my clients concerning the performance of his ornamental plants. On closer inspection, it came to my attention that the main cause of the problem arose from the planting media.
I therefore thought it wise to highlight to you what makes a planting media good or what could be the characteristics of a good planting media.
Apart from light,temperatures and moisture,the performance of an ornamental plant is also determined by the type of the planting media it is growing in. There are a number of type of substrates through which ornamental plants can grow among them heavy clay soil ,sand ,peat. It should not be forgotten that the substrate should be free from toxins and pests and should be given the proper balance of water and fertiliser. The ornamental industry in Kenya has changed over the years such that many growers of ornamental indoor plants have resorted to soilless media including cocopit (coir), pumice (tuff), rice hulls, wheat straws, saw-dust, coconut husks and barks. Initially, many growers used compost field soil as the preferred media for ornamental plants.
Soilless media is popular with large commercial ornamental plant propagators because of its excellent capacity to retain irrigation water.
The core functions of a planting media a grower should check include:
-Supplying nutrients to the ornamental plant.
– Providing support to the ornamental plants.
When checking for the characteristics of a good planting media ensure that
1. It has good aeration.
2.Good water holding capacity favourable to the ornamental plant.
3.Clean from diseases and pests.
4. Good particle size to allow free flow of water during irrigation.
5. Easy to transport and not to bulky.
6.Easy to handle – should not be too sticky.
7. The planting media should also be composed of readily available components.
Components of a good planting media for ornamental plants should have a mixture of:
a) Clay, sandy or loam soil, though loam is the best.
b)Decomposed plant matter such as peat moss,muck(decomposed plant leaves) to improve water holding capacity.
c)Coarse matter such as sand, charcoal or vermiculite to improve water percolation.
When it comes to mixing a good potting media, the ratios depend on the crop species and root system of the individual ornamental plant. The root system could be tap or fibrous. Another point of concern is that when filling containers to plant ornamentals, one should always work with moist or damp media to avoid media flowing freely through the container drainage holes.
Sterilizing Plant Media
Growers planting high value disease susceptible ornamentals might find it necessary to sterilize planting media for ornamentals. This ensures the media is free from insect pests and disease pathogens. There are several methods used in sterilizing planting media such as
a) Steam Sterilization
In this method water is heated and steam passed through a planting media via steam pipes for a given time duration. Insects and some pathogens are destroyed during this process.
This involves moistening and covering the planting media with clear polythene papers and leaving this in the open sun for a period ranging from 3-6 months. High temperatures attained at the hot part of the day destroys insect pests and a large percentage of other disease causing pathogens.
Though solarization is not as effective as steam or chemical sterilization.
c) Chemical sterilization
In this method, Basamid is the chemical used to sterilize soils and other growing media. Methyl bromide was the chemical used formerly to sterilize planting media but it was banned in the year 2004 because of its residual properties in the food chain.
In the use of fertilizers with planting media, the fertilizer to be used for planting should be added to the sterilized media just before planting.
At planting time ,DAP (Diammonium phosphate)fertilizer maybe used or slow release NPK fertilizers which are available from special supplies shops. An example of a slow release fertilizer used for indoor ornamental plant container is the osmocote.
Mistakes to Avoid.
–Compaction of the media when handling media for ornamentals. This excludes air from the root zone.
-Extreme pH, always check on the pH to ensure it is favourable to the ornamental you are growing.
-Many ornamentals are moved to indoor environments where they are restricted into shallow or deep containers that contain media which may not be well balanced.
This also means they won’t receive direct natural rainfall to clean up the foliage and leach away excessive nutrients from the root zone
-Plant containers lacking drainage holes are likely to have rotten roots due to excess water logging conditions.
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