Schlumbergera (Christmas Cactus) is a relatively easy-to-care-for indoor plant. In China, it is called "蟹爪兰" (Crab Claw Cactus) because its segmented stems resemble a crab's claws. In Western countries, it is known as "Christmas Cactus" because it typically blooms around Christmas time. Below are the care instructions:
Light:
Prefers gentle direct sunlight and bright, indirect light. Avoid strong direct sunlight, as it can scorch the leaves.
In summer, it’s best to place it outdoors in a partially shaded area, such as a spot that receives direct sunlight only in the morning. Adequate gentle light helps accumulate nutrients, leading to abundant blooms during the Christmas season.
In winter, when kept indoors, place it near an east-, north-, or west-facing window. If placed near a south-facing window, consider moving it slightly away from the window if the sunlight is too intense.
Temperature:
The ideal temperature range for growth is 15-25°C (59-77°F). It is sensitive to cold, so avoid temperatures below 10°C (50°F) in winter.
Watering:
Keep the soil slightly moist, avoiding waterlogging and letting the soil dry out completely. Water when the top layer of soil becomes dry, but the inside of the pot is still moist.
During the blooming period, the soil should be kept moderately moist but not overly wet. Water when the topsoil is slightly dry, and avoid letting the soil dry out completely or become too soggy, as either can cause the flowers to wilt prematurely.
Humidity:
Christmas Cactus prefers high humidity. You can increase humidity by misting around the plant or using a humidifier.
Soil:
Use well-draining soil, such as cactus or succulent soil mix. You can also mix regular potting soil with coarse sand or perlite.
Fertilization:
During May, June, July, and August, fertilize every 10 days, alternating between a balanced general-purpose fertilizer (N-P-K ratio of 20-20-20 or 10-15-10) and a high phosphorus and potassium fertilizer (N-P-K ratio of 15-30-15 or potassium dihydrogen phosphate).
In other months, fertilize once a month using only a balanced general-purpose fertilizer.
If you’re taking steps to promote flowering before bud formation, refrain from fertilizing for two weeks.
Flower Promotion:
A month before flower buds form (in Toronto, this can be from mid-July to mid-August), prune off the top one or two young leaves at the ends of the stems, leaving only healthy mature leaves. Generally, flower buds will form on the mature leaves about a month later.
If you prefer not to prune, you can leave the young leaves, but the plant will only bloom once these leaves have matured, and the number of flowers will be significantly fewer than with the pruning method.
Two weeks before bud formation, slightly delay watering, pause fertilizing, and provide relatively lower temperatures and slightly shorter daylight hours (i.e., longer dark periods; you can cover the plant with a box in the evening and remove it in the morning). This will help promote bud formation. Once the buds form, resume normal watering, fertilizing, and lighting.
Repotting:
Repot every 2-3 years, ideally in spring. When repotting, you can prune the roots to encourage new growth.
Pruning:
After the blooming period, you can prune the plant to maintain its shape. Pruning also encourages more branching, which increases the number of flowers in the following year.
Reasons Why Christmas Cactus Might Not Bloom:
1）Insufficient Light:
If the plant has been exposed to insufficient light for a long period, it may not have accumulated enough energy to bloom.
2）Excessive Light During Bud Formation:
During the bud formation period in autumn, if the plant receives more than 12 hours of light per day (e.g., exposed to artificial light at night), it can inhibit bud formation, leading to no blooms.
3）Temperature Issues:
Excessively high or low temperatures can prevent bud formation. Maintaining temperatures between 15-18°C (59-64°F) in autumn is conducive to bud formation.
4）Improper Watering:
Both overwatering and underwatering during the bud formation period can affect bud formation. If the soil is too wet, the roots may rot, affecting nutrient absorption, and thus blooming. On the other hand, if the soil is too dry, the plant may not have enough water and nutrients to support bud formation.
5）Improper Fertilization:
Unbalanced fertilization or lack of fertilization can also affect blooming. Excess nitrogen fertilizer promotes leaf growth but inhibits bud formation. Use a balanced fertilizer during the growing season and reduce fertilization before buds form.
6）Pruning:
If the Christmas Cactus is not pruned properly, the stems may become too long or too dense, affecting light and air circulation, which in turn affects blooming. Proper pruning can promote new branching, increasing the chances of blooming.
7）Age of the Plant:
A Christmas Cactus needs to reach a certain level of maturity before it can bloom. A plant that is too young may not bloom.
8）Sudden Environmental Changes:
Sudden changes in the environment, such as moving the plant, changing light conditions, or temperature fluctuations, can cause the plant to stop growing or become stressed, affecting bud formation and blooming.
9）Unhealthy Plant:
If the Christmas Cactus is not healthy, with weak roots and thin leaves, it may not bloom. Focus on nursing the plant back to health before expecting it to bloom.
蟹爪兰（Schlumbergera）是一种比较容易养护的室内植物，在中国它叫蟹爪兰，因为它的节径连接形状像螃蟹的副爪。在西方国家，它被叫做圣诞仙人掌（Christmas Cactus），因为它的花期一般在圣诞节期间。以下是它的养护方法：
光照：
喜欢温和的直射阳光和明亮的散射光，避免强烈的阳光直射，否则叶片有可能被晒伤。
夏天最好摆放在室外，放在部分遮荫的位置，比如只在上午有阳光直射的位置。充足的温和光照有助于营养积累，到圣诞节期间才会开出大量的花朵。
冬天摆放在室内时，可以摆放在朝东、朝北、朝西的窗口旁，如果放在朝南的窗口旁，如果阳光过于猛烈，可以摆放在离南窗口稍远的位置。
温度：
适宜的生长温度为15-25°C。它对寒冷比较敏感，所以在冬季要避免温度低于10°C。
浇水：
保持土壤略微湿润，避免积水，避免土壤干透。在表层土壤变干时，花盆内部还是湿润的，这时就要浇水。
蟹爪兰开花期间，土壤应该保持适度湿润，同时不能过湿，等到表层土壤稍微干燥时就浇水，避免让土壤完全干透或过于潮湿，这两者都可能导致花朵过早凋谢。
湿度：
蟹爪兰喜欢较高的空气湿度。可以通过在周围喷雾或放置加湿器来提高湿度。
土壤：
使用排水良好的土壤，如仙人掌或多肉植物专用土壤。也可以使用普通营养土加上粗沙或珍珠岩。
施肥：
在5、6、7、8月期间，每10天施肥一次，营养均衡的通用肥（氮磷钾比例20-20-20， 或者10-15-10）和高磷钾肥（氮磷钾比例15-30-15，或者磷酸二氢钾）轮换使用。
其他月份每月施肥一次，只使用营养均衡的通用肥。
如果在花芽形成之前采取促花措施，那2个星期内不施肥。
促花：
在花芽形成的前一个月（在多伦多可以在7月中旬到8月中旬），把枝条顶端一到两片嫩叶修剪掉，只留下健康的老叶，一般一个月之后会有花芽在老叶片上形成。
如果不想修剪嫩叶，也可以不修剪，只有等嫩叶长到足够老时，它才会开花，并且花量比前面的方法会少很多。
在花芽形成之前的两个星期，稍微延迟浇水，暂停施肥，提供相对较低的温度，延长黑暗时间（可以在傍晚用纸箱罩住植物，到早上再拿开纸箱），这都有助于花芽形成。等花芽形成后，切记恢复正常的浇水、施肥和光照。
换盆：
每2-3年换一次盆，最好在春季进行。换盆时可修剪根系，促进新的生长。
修剪：
花期结束后，可以适当修剪以保持植物的形状。修剪还可以促进更多的分枝，从而增加来年开花的数量。
蟹爪兰不开花的原因：
1）长期光照不足，没有积累足够的能量来开花。
2）在秋季花苞形成期，每日得到的光照超过12个小时，比如夜晚受到灯光照射，会抑制花芽的形成，导致不开花。
3）环境温度过高或过低，可能会导致花芽难以形成。秋季温度在15-18°C之间，有助于花芽的形成。
4）浇水不当：在花芽形成期间，浇水过多或过少都可能影响花芽的形成。如果土壤过于湿润，容易导致根部腐烂，影响养分的吸收，从而影响开花。相反，土壤过于干燥也会导致植物缺乏足够的水分和养分来支持花芽的形成。
5）施肥不当：施肥不均衡或缺乏施肥也会影响开花。过多的氮肥会促进叶片的生长，同时会抑制花芽的形成。应在生长季节使用氮磷钾和各种营养都均衡的肥料，并在花芽形成前减少施肥。
6）修剪：如果蟹爪兰没有适当的修剪，枝条可能会过长或过密，影响光照和通风，从而影响开花。适当的修剪可以促进新的分枝，从而增加开花的机会。
7）花龄：一棵蟹爪兰需要达到一定的成熟度后才会开花，太年轻的蟹爪兰不会开花。
8）突然的环境变化，如搬动、光照条件改变、温度骤变等，可能会导致蟹爪兰出现生长停滞或不适，影响花芽的形成和开花。
9）蟹爪兰不健康，根系弱小，叶片单薄，需要把植物养健康后才有可能开花。
Source from chat.openai. Organized and translated by Qiuye. Not for reprint. 不得转载！