Gadenin日本語Get the appWhat the sheath is and why it stands empty
As a new cattleya growth finishes expanding, a flat green pouch appears at the very top, standing upright against the base of the leaf. That is the sheath, and it is the case the flower buds will emerge from. Its arrival is a good sign: the plant has built a growth strong enough to think about flowering. What it is not is a promise of flowers next week.
In many cattleyas the sheath forms as the growth matures and then does nothing at all for two, three, even six months while the plant waits for its own flowering cue. During that pause the sheath usually turns from green to papery beige or brown, and it can look completely dead. That color change is normal and means nothing about whether buds are coming. A great many perfectly good cattleya flowers are cut off by owners who read a dry sheath as failure.
Leave it alone. When the plant is ready, buds swell inside the sheath and you will see it thicken and go lumpy, and within two to four weeks the buds push out of the top and open. Until then, the correct action is nothing at all except keeping the light strong and the watering on its normal rhythm.
| Sheath condition | What it means | What to do |
|---|---|---|
| Flat, green, standing upright | Newly formed, waiting for the flowering cue | Leave it, keep light strong |
| Dry, papery, beige or brown, still flat | Dormant sheath, very common, can still flower | Leave it, do not cut |
| Swelling and lumpy, buds visible against the light | Buds developing, flowers in two to four weeks | Stop moving the plant, keep the sheath dry |
| Brown, soft and wet at the base | Water sat in it and the buds are rotting | Slit it open, dry it out, improve air movement |
| Old, dry and empty a year on, new growth started | That growth has passed its chance | Trim it off cleanly, focus on the new growth |
When to open a sheath, and how
There is one situation where you should interfere. If buds are developing inside a sheath that has dried hard, they can occasionally fail to break out and grow crooked inside it, or water trapped in the sheath can rot them. Hold the sheath up to a bright light: if you can see the shadow of buds inside and the sheath is hard and papery, or if the sheath feels wet inside, open it.
Slit the sheath down one side only, along its length, using the very tip of a sterile blade or a fingernail, and peel that side back like a jacket rather than pulling the whole thing off. Cut only the sheath, not the growth behind it. Once opened, the buds finish developing in the open air and often develop better for it.
If a sheath has filled with water after overhead watering or a rain shower outdoors, tip the plant on its side to drain it and slit the sheath to let air in. Buds sitting in trapped water go brown and mushy within days, and this is a frequent cause of a plant that sheaths reliably and never delivers.
Some cattleyas flower straight out of a new growth with no sheath at all, and some make a sheath and flower immediately as the growth matures. None of these habits is a fault. Watch what your own plant does for a couple of cycles and you will know which pattern to expect from it.
Why buds fail to appear at all
The commonest reason is light. A cattleya grown in dark green foliage has bulbs without the reserves to spend on flowers, and it will keep making leaves indefinitely without complaint. This is not fixed by fertilizer and it is not fixed in the flowering season; it is fixed by moving the plant to a much brighter position and waiting for the growth that builds there. Read the leaf color, not the label on the plant.
The second reason is temperature. Cattleyas flower better with a night that is 10F to 15F (6C to 8C) cooler than the day, and a plant kept at a flat 72F (22C) around the clock in a centrally heated room often stalls. A summer outdoors, or simply a cooler room at night in autumn, supplies that swing.
The third is disturbance. A plant repotted while its sheath was developing, or moved to a new position once buds had started swelling, commonly aborts. Cattleyas are strongly cued by their orientation to the light, and turning a potted plant round while buds are forming can make them grow crooked or drop. Once a sheath goes lumpy, settle the plant and stop handling it.
The fourth is age and size. A division of three bulbs, or a seedling, will not flower until it has built bulbs of mature size for that plant, which can take three to five years. There is nothing to correct; it needs to grow.
Bud blast: buds that yellow and drop
Bud blast is when developing buds yellow at the stalk and fall off one by one instead of opening. The usual causes are dry rising heat from a radiator or vent, a sudden cold draft, ethylene gas from ripening fruit or a gas appliance in the room, or a sharp change in watering while buds are swelling.
The remedy is stability. Once buds show, keep the plant in one place, out of the path of heating and cooling vents, away from the fruit bowl, and on the same watering rhythm it has been on. Do not feed heavily at this point, and do not let the pot go from bone dry to soaked and back in an attempt to help.
Water on open buds also marks them. Water the mix, not the plant, from the moment the sheath starts to swell, and if the plant lives outdoors bring it under cover once buds are visible.
The flowers themselves, and what to record
Cattleya flowers take a few days after opening to reach full size and color, and they harden as they age. Blooms last two to three weeks on the plant in a cool, bright, airy spot, less in a hot dry room. Keeping them dry and out of direct midday sun once open extends them noticeably. Cutting the flowers for a vase takes energy from the plant that would otherwise go into the next growth, so cut sparingly on a young plant.
When flowering finishes, snip the spent flower stem back close to the sheath and leave everything else. That growth will not flower again, but its pseudobulb feeds the next one for years, so nothing else is removed.
Record the date the sheath appeared, the date the buds became visible, and the date the first flower opened, for each growth. After two cycles you will know how long your plant's own pause between sheath and bud runs, and that single number is what stops you cutting a good sheath off next time.