In-depth Reflection and Comprehensive Analysis of Sand Materials

Particles with a diameter of less than 3 mm are sand, and those larger than 3 mm are gravel. Sand materials are further divided into coarse and fine grades; their water retention depends on particle size - the smaller the particles, the more water they retain, and the larger the particles, the less water they retain. For growing orchids, pure river sand should be chosen as the sand material; sand containing salt or lime should be avoided. Sand material with too much lime tends to be alkaline, which can fix elements such as inorganic iron. Pure sand is generally used as a medium for cuttings and seedling beds. It can also be used as a medium fororchidsfor temporary planting. Because river sand contains no nutrients, has no micropores, and is very poor at absorbing fertilizer and retaining moisture and fertilizer, using it alone for long-term orchid growing gives very unsatisfactory results. However, river sand is still an excellentcultivationmedium. Its advantages are: 1) good aeration; 2) it can promote rooting; 3) stable physical and chemical properties; 4) good drainage. Therefore, river sand is often widely used as one of the base materials in various mixed media. Some people advocate using all-sand orchid cultivation to induce variegation. The author has tried it for many years and has not seen any case in which variegation was produced for this reason and could remain stable, nor have I seen any reports of success in this regard. The cause of sudden variegation in orchid plants remains a mystery that has not yet been fully solved, baffling and leaving people hesitant and confused. The causes of variegation mentioned in media reports are mostly speculation and fail to explain the real reason, and discussions on this subject still lack sufficient scientific basis. This is just a narrow personal view; I dare not regard it as authoritative. Please forgive my presumptuous words, gentlemen, do not laugh, and I look forward to your corrections! Author: Zhang Bingfu, Zheng Qiuxiang Address: Shengyuan Cuo, Dongxiao Xilian, Longyan City, Fujian Province Home phone: (0597)2790583 (0597)2238080 Postcode: 364012