How should fertilizer and water management be done when orchids are grown in hard potting media?

OrchidsCultivation：OrchidsHard Potting Media and Fertilizer and Water Management

I. Watering
Hard potting mediaGrowing orchidsrequires frequent watering. Every winter, when orchids are dormant, water once every two to three days. From April onward, when orchids wake up and begin growing, water once a day. In the dry seasons of summer and autumn, water twice a day. There are three watering methods: pouring, spraying and soaking. Pouring means using a ladle to pour water into the pot; its advantages are saving effort and time, while its disadvantage is water going everywhere. Because hard potting media do not absorb water easily, the spots you pour on get water while the spots you miss stay dry, so you must pour thoroughly several times over the whole surface; do not assume it is fine just because water runs out of the bottom of the pot. Spraying means using a sprayer to spray water onto the potting medium; it takes more time, but uses less water and will not make a terrible watery mess. Soaking means the soak-the-pot method; the potting medium absorbs water evenly, but it is troublesome to do. Which method to use depends on the weather (temperature and humidity). When the temperature is high and the air is dry, use pouring or soaking; when the temperature is low and the air humidity is high, you can use spraying. Under normal circumstances, you can use pouring or soaking on the first day, and spraying on the second day. In short, suit measures to the time and do not be rigid.

II. Moisture Retention
The moisture retention of hard potting media is related to particle size: large particles mean large gaps and more evaporation; small particles mean small gaps and less evaporation. Mixing large and small particles can improve moisture retention. But moisture retention is still limited, far inferior to soft potting media. Even a moment of neglect can cause problems. For this reason, I did a comparative experiment on moisture retention: using identical flower pots, pot A was filled with pure "xiantu" (orchid soil), and pot B was filled with a 3:1 mix of xiantu and sawdust. The soak-the-pot method was used to make the potting media fully absorb water. After 4 days, the pots were turned out to check the potting media: pot A's potting medium was completely dry, while pot B's potting medium was still moist except for the surface layer. Pot B's moisture retention was much stronger than pot A's. However, for types between terrestrial orchids and epiphytic orchids (such as Golden Little Prodigy), it is not advisable to add sawdust.

III. Fertilizing
Hard potting media do not absorb fertilizer solution the way soil does, "drinking" it up fully; only the surface of the potting medium becomes slightly moist, and when you water the next day, this fertilizer is carried out of the pot again, so you must fertilize frequently. Generally, during the growing season, orchids are given a 0.1%-0.2% chemical fertilizer solution once every 10-15 days. Fertilizing can use the circulating fertilization method. Before fertilizing, prepare several washbasins, place the flower pot in a basin, repeatedly pour the fertilizer solution through the potting medium, then move it to another empty basin to drain. In this way, the fertilizer solution that flows out is used again in circulation. Before September each year, apply mainly nitrogen fertilizer; after September, apply mainly phosphorus and potassium fertilizer.

Dry cake-fertilizer blocks have an automatic fertilizing effect and are especially suitable for growing orchids in hard potting media. The method for making dry cake-fertilizer blocks is as follows: put cake fertilizer in a basin or jar, add an appropriate amount of water, seal it with plastic film, and let it rot. After half a year to a year, sun-dry it until it becomes a dry block that does not dissolve when it meets water. Break off one or two small dry blocks and place them on the surface of the pot; when you spray or water, the dry blocks become damp and a tiny amount seeps into the potting medium to provide nutrients. After some days, move their position so that the fertilizer solution does not seep into a fixed spot. Doing this once every spring is enough, and it saves effort once and for all.