Which orchids need vernalization to bloom?

Vernalization is a low-temperature process that many cold-hardy flowering plants must go through to trigger blooming. Orchids such as Cymbidium goeringii and Cymbidium faberi all need a period of sustained low-temperature treatment to promote flower bud differentiation, otherwise they cannot form buds. Many people find that their potted orchids never bloom, and it is quite likely that the orchid variety you are growing needs vernalization and you did not know it, or you knew but did not know how to handle it.

Different orchid varieties have different temperature requirements for vernalization. For example, orchids such as Cymbidium sinense, Cymbidium ensifolium and Cymbidium kanran can bloom naturally without deliberately undergoing low-temperature vernalization, while varieties such as Cymbidium goeringii and Cymbidium faberi absolutely must go through low-temperature vernalization. Of course, this does not mean that orchids that do not need vernalization require no temperature control when blooming; for instance, Cymbidium sinense is prone to stalled or aborted buds when the temperature is too low or too high, which can also cause failure to bloom, or an unsatisfactory bloom even if it does flower.

The main purpose of vernalization is to let orchids with flower buds enter a period of dormancy and accumulate nutrients, and to let orchids without flower buds, through vernalization and dormancy, grow and bloom better the following year. So when is the best time to vernalize potted orchids, and how should vernalization be done to make them bloom? Below we take Cymbidium goeringii as an example to look at its vernalization methods and precautions:

1. Vernalization time for Cymbidium goeringii

The ideal temperature for vernalization is between 4-10 degrees. For potted Cymbidium goeringii in the north, usually when the flower buds have emerged about 3-4 cm, when the buds stop growing taller and appear slightly rounded and plump, place the pot in a 4-10 degree environment and vernalization can begin.

2. Vernalization duration for Cymbidium goeringii

Generally speaking, the longer the vernalization the better. Cymbidium goeringii usually needs 30-40 days of vernalization, the vernalization period for Cymbidium ensifolium var. misericors and Cymbidium tortisepalum is best at 40-50 days, and Cymbidium faberi and Songchun generally need more than two months.

3. Precautions during the vernalization period

During vernalization, the humidity of the potted orchid must not be too high; pay attention to water control and keep it on the drier side as much as possible, otherwise it is easy to cause root rot or bud rot. In addition, in order to accumulate nutrients so that the flowers are large and vividly colored after vernalization, apply a foliar fertilizer once before vernalization. After the vernalization period, water thoroughly (be careful to avoid the flower buds), then first place the potted orchid in a 15 degree environment for a transition before moving it indoors, to avoid a sudden temperature rise causing heat-stalled or aborted buds.

All right, the above are the methods and precautions for orchid vernalization. Friends who grow orchids but find they do not bloom can take note and check whether your potted orchid has already been vernalized, and whether everything that needs attention during vernalization has been done correctly.