The correct method for repotting orchids and changing the soil in spring

The whole year's work depends on a good start in spring, and before we know it, spring has returned to the earth again. Spring is the golden season for an orchid's annual growth, and it is also the crucial moment for repotting, dividing and sprouting. At the same time, it is also the time for orchid growers to check and summarise the results of the previous year's orchid cultivation.

The optimal temperature for dividing and replanting orchids is 5-15 degrees. 10 degrees is the threshold temperature for orchid dormancy. Therefore, repotting at around 10 degrees has the least impact on the orchid, so repotting can be done in both spring and autumn.

As the saying goes, "Repot in spring and you get leaves, repot in autumn and you get flowers; repot often and you get leaves, repot rarely and you get flowers." This is the repotting principle that orchid growers keep firmly in mind.

Generally, repotting should be carried out in the two seasons of spring and autumn, with the period around Qingming in spring and around the Autumn Equinox in autumn being suitable. Judging from how well the plants establish, when repotting in autumn, the orchid then enters its winter dormancy period, so the time to re-establish is short.

When repotting in spring, the orchid will quickly enter a vigorous growth period, so spring repotting is better than autumn repotting. Summer is hot and winter is cold, and both are dormancy periods for orchids. Repotting in these seasons is not conducive to the orchid re-establishing.

I have exchanged views with many orchid friends online. Regarding the interval between repottings, most believe that repotting orchids and changing the soil should not be done too frequently, and that once every two to three years is best. This is because orchids do not like to be "moved around", and repotting less often can still produce strong plants.

Repotting orchids and changing the soil is inextricably linked to a person's cultivation habits, potting medium and management. I tend to repot once a year and replace the medium with new material.

Orchid cultivation developed relatively early in Sichuan, and the cultivation techniques for Chinese orchids there can be considered second to none nationwide. I am in the north, which is a non-orchid-producing area. Most of the friends I have contact with and the orchid seedlings I buy come from Sichuan. In order to help the orchids adapt to the northern environment as quickly as possible, the potting medium I choose, the adjustment of the microclimate and the management are basically the same as in Sichuan.

The choice of potting medium may seem like a minor detail in the process of growing orchids. But if it is not handled well, problems can also arise. In mild cases the plants collapse, and in severe cases the whole lot is lost. It is one of the key factors determining success or failure in cultivation.

Each person's choice of potting medium differs according to the orchid variety, the regional cultivation environment and the grower's level of understanding of orchid cultivation. As long as it can work with one's own cultivation environment and management to make the orchid grow healthily and vigorously, any potting medium can be used.

Now I will write down the types of potting medium I use, their treatment methods, the mixing ratios and the planting process.

Types of potting medium and mixing ratios

Bottom soil: 70% medium-grade fired clay granules, 30% charcoal granules

Base soil: 10% medium-grade fired clay granules, 25% small fired clay granules, 10% medium-grade Xiantu, 25% small Xiantu granules, 20% oak leaves, 10% peat, plus charcoal and active soil

Top soil: place a layer of peat, active soil and Zhixiang near the pseudobulb, then place a layer of small fired clay granules.

Peat: also called grass coal, or Yuexi soil. It is the product of plants in marshes after biological decomposition. However, because it contains too many impurities, it must be washed many times and sterilised (refined washed finished products are now available). It is excellent for weak root systems and tissue-cultured seedlings.

Before use, it can first be soaked in boiling water, drained, cooled, and sprayed with 500 times diluted Lanjunwang.

Fired clay: made from natural clay fired at high temperature. Its granules are hollow, with many fine, rounded pores on the surface. Therefore, it has good water absorption and water retention.

Before use, it should be rinsed frequently with water so that it absorbs water, loses its fiery nature and has its powder washed away, then dried until half-dry for later use.

Xiantu: also called peat, it is formed from organic matter such as trees and weeds after tens of millions of years of decomposition, and is rich in humus and humic acid.

Before use, it can be soaked for one to two days, washed free of powder, and dried until half-dry for later use.

Oak leaves and Qinggang leaves: in nature, wild orchids often grow in oak forests and Qinggang forests. Their leaves, branches, bark and so on are most suitable for the reproduction of orchid bacteria and other beneficial bacteria. Comparing the two, Qinggang leaves are much better than oak leaves, but because there are fewer such trees, the price is relatively higher. Generally, oak leaves are used. Among them, thorny oak leaves are the best.

Before use, they need to be fully fermented. On the market there are only semi-fermented and roasted ones. If not needed urgently, in summer, put oak leaves and a small amount of branches about one cun long into a black plastic bag, along with yeast tablets, fungicide and insecticide. Sprinkle with water, tie tightly, and leave in the sun for a period of time to let them ferment. Use after complete fermentation. (Yeast tablets can speed up fermentation, and fungicide and insecticide can completely kill the bacteria and insect eggs in the oak leaves.)

If needed urgently, they can be pressed in a pressure cooker for half an hour or boiled for two hours until the leaves feel a little soft.

Charcoal: especially charcoal that has just been made not long ago, contains a large amount of activated carbon, has strong adsorption capacity and has disinfecting, sterilising and bacteria-inhibiting effects. It is best to use charcoal made from wood. The charcoal used for barbecuing on the market is machine-made, easily crumbles, and contains impurities such as coal dust, so it cannot be used.

Charcoal has a sterilising effect. Therefore, it should not make up 5% of the potting medium ratio in each pot. Using it to cushion the bottom of the pot is best.

When planting, make sure the orchid roots are in full contact with the granular potting medium. Many hollow roots are the result of not handling this aspect well.

First, for the orchid plant, cut off hollow roots, rotten roots and broken roots. After disinfection, sun them until the orchid roots turn white, are slightly soft and full of elasticity, which is the best state. Never let them become too dry.

When planting, first mix the bottom material, put it into the bottom of the pot to about one third, and place the orchid in the pot. Then use the mixed base soil, adding material while gently shaking the pot. You can also use chopsticks to insert up and down so that the orchid roots separate from one another and make full contact with the granules. Fill up to near the pseudobulb, then use both hands to gently tap the pot on the ground so that there are no gaps around the orchid roots. Place a layer of peat, active soil and Zhixiang near the pseudobulb, then place a layer of small fired clay granules. The pseudobulb should be level with the rim of the pot. Cover the pseudobulb just barely with the potting medium and shape it into a steamed-bun form. Spray the orchid leaves with clean water to wash them, water thoroughly, and place in a cool, ventilated place to re-establish. In addition, the potting medium granules used in cultivation nowadays are generally relatively large, so be sure to plant firmly when potting to prevent roots from being trapped.

I tend to repot and change the soil once a year, and this has many benefits.

One. Reviewing experience: repotting every year lets you see the thickness of the roots and the growth of the orchid. You can review the gains and losses of the previous year's fertiliser, water and orchid management experience, so that timely adjustments can be made for the coming year. At the same time, during the repotting process, hollow roots are cleaned up, old roots are combed out, and the breeding ground for pathogens is reduced. Replacing the potting medium and choosing the orchid pot are also done at the same time.

Two. Replacing and loosening the potting medium

1. If orchids are grown in orchid mud, repotting every year can prevent the potting soil from compacting, and prevent orchid roots from being smothered to death due to compacted potting soil, or drying to death because water cannot penetrate when watering.

2. If granular potting medium is used and there is no disease, and you do not want to replace it with new medium, you can repot, comb the orchid roots and air them until the orchid roots turn white, are slightly soft and full of elasticity, then replant with the old medium. Doing this can ensure moisture in the lower part of the potting soil.

After a year of growth, the potting medium in the pot forms certain water channels. Whenever watering is done, a large amount of water rushes down along the gaps by the pot wall. From the outside it looks as if it has been watered through. In fact, only the topsoil and the surface of the lower potting soil have been moistened a little, and they dry out very quickly. This cannot meet the needs of orchid root growth. The orchid roots grown this way grow sideways, and the original strong roots below become hollow due to loss of water. Thus the orchid becomes weaker and weaker the longer it is grown.

Three. Replacing pesticides

Changing to new potting medium every year helps prevent the orchid's own resistance from weakening due to acidification of the potting medium. New potting medium can replace pesticides, reduce the number of times fertiliser and medicine are used, and reduce the plant's resistance to chemicals, achieving three benefits at once.

Four. Increasing the germination rate

Many fine orchid varieties have a low germination rate, often producing only one new shoot from three or four plants. Repotting every year in this way gives the orchid a sense of crisis and can increase the germination rate to a certain extent. If you also soak the orchid roots for one hour in commercial fertilisers such as Lanjunwang and Cugensheng, the effect is even more obvious. Not only does it increase the germination rate, but the shoots produced are also strong.

Five. Reducing losses

Proper division can reduce the risk of death from disease, so that a single outbreak does not kill the whole pot and cause the loss of precious orchid varieties. (Eggs cannot all be put in one basket.)