Can Pure Soil Support the Growth of Orchids?
Orchids are被誉为 the gentlemen of flowers, admired for their elegant posture by gardening enthusiasts. However, to ensure the healthy growth of these noble flowers, the choice of substrate is crucial. Many新手 gardeners often struggle with whether they can use pure soil directly, but in fact, this needs to be judged comprehensively based on the characteristics of the orchid variety and the scientific proportion of the substrate.
I. Analysis of Orchid Root Growth Characteristics
1.1 Difference Between Terrestrial and Epiphytic Orchids
Chinese orchids belong to terrestrial orchids, thriving in humid mountainous areas rich in humus, with roots adapted to the soil environment. Tropical orchids are mostly epiphytic, with aerial roots needing to climb tree bark for growth. The former can be cultivated using improved soil, while the latter requires a granular substrate.
1.2 Feasibility of Cultivating in Pure Soil
While terrestrial orchids can use pure soil, three elements must be met: humus content >40%, adding 30% perlite to enhance aeration, and a stable pH of 5.5-6.5. Using ordinary garden soil directly can lead to compaction, and it is recommended to mix it with pine needle soil for improvement.
II. Golden Ratio for High-Quality Orchid Substrate
2.1 Basic Material Selection
Recommended formula: 3 parts fermented pine bark for attachment points, 2 parts volcanic rock for aeration, and 1 part moss for moisture retention. This ratio simulates the natural growth environment of orchid plants, with an air porosity of over 35%.
2.2 Functional Additives
Incorporating 5% bamboo charcoal granules can adjust the pH, and adding vermiculite can improve fertilizer retention. Supplementing 10% decomposed sheep manure annually can continuously release nitrogen, phosphorus, and potassium elements.
III. Key Indicators for Substrate Maintenance
3.1 Control of Aeration and Drainage
The ideal substrate should drain clean water within 15 seconds after watering, which can be achieved by adding a 3cm layer of ceramic stones at the bottom. Regularly use a bamboo skewer to check the moisture of the potting soil, maintaining an internal air porosity of over 25%.
3.2 Sustained Fertility (G-Y)
Use a combination of slow-release fertilizer and foliar fertilizer: pre-bury Ogreen 318s in the substrate and supplement with potassium dihydrogen phosphate foliar fertilizer monthly. Avoid using urea-based fast-acting fertilizers to prevent root burning.
Mastering these essential principles of substrate configuration, whether it's terrestrial varieties like Cymbidium and Eulophia, or epiphytic categories like Phalaenopsis and Dendrobium, can establish an ideal growth environment. Regularly observing the root status and replacing the substrate every 2 years can keep orchids vibrant and healthy.