Pots for Cattleya, wide, shallow, and mostly open air.

The ones to skip

We make these and they are good pieces. They are not for this plant, and here is the reason in each case.

• Flush Vessel 180Self-watering. There is no version of this plant that wants a reservoir.
• Root View 130A Phalaenopsis pot. It is a circle for a monopodial plant with no rhizome, and a Cattleya will walk straight over the rim of it in two seasons.
• Fine Grade 140Drawn for the fine mixes Oncidium types want. A Cattleya in a fine medium stays wet at the root and that is the failure this plant dies of.
• Column Pot 140A plain pot with soil-shaped proportions. Too deep, too closed, and nothing for the rhizome to run along.

The numbers we draw to

The run

About 100 mm of clear pot ahead of the leading growth, which is two to three years

Depth

78 mm of medium, and no more, whatever the width

Open wall

34 percent, which is what makes the middle of the pot dry at the same rate as the edge

Medium grade

12 mm bark and up. Anything finer falls through the slots and holds too much water anyway

Repotting

As new roots start, not when the plant looks tired. Roughly every two years

These are the figures the pieces are drawn to rather than measurements taken off a finished one, and they are a starting point for your plant rather than a rule. Send us what it is in now and we will move them.

Why it is a run and not a circle

A Cattleya is sympodial: it grows sideways along a rhizome, one pseudobulb at a time, in one direction. Pot it in the middle of a round pot and half the pot is behind it, permanently unused, holding wet bark. Within two seasons the leading growth is out over the rim and the whole thing has to be repotted.

So we draw it as a run. The oldest back bulbs go against one end, on a seat drawn for them, and the whole length of the pot is in front of the leading growth. About 100 mm is two to three years, which is also roughly how long the bark lasts before it breaks down. The pot and the medium reach the end of their lives at the same time, which is deliberate.

The medium

Coarse bark, 12 to 18 mm, with charcoal and a little perlite or lava rock. Nothing fine. It should rattle when you pour it and you should be able to see daylight through a handful.

The mix is not there to hold water. It is there to hold the plant up while the roots do what they do in a tree, which is grab water fast and then dry. When the bark has broken down into something soft and dark, it is finished, whether or not the plant has filled the pot.

Water hard, then let it dry

Run water through it until it pours out, for longer than feels sensible, and then do not water again until the pot is light and the medium is dry through. In a bright Yerevan summer that might be twice a week; in winter it might be every ten days.

The roots want the wet and dry cycle, not an average. A plant kept evenly damp is the one that loses its roots, and because the pseudobulbs hold reserves, it goes on looking fine for months after the roots have gone.

When to repot, which is the thing people get wrong

Repot when new roots are just starting from the base of the newest growth, as green tips a few millimetres long. Those roots will take hold in fresh medium. Roots that are already long and established will mostly be damaged in the move and will not replace themselves until the next growth cycle.

It is a spring job most years. Do it when the plant is telling you rather than when the calendar is.

Keep reading

• Why a wet root suffocates
• What a mix is measured on
• What a bright window really is

Other plants

• Aroids
• Cacti
• Succulents
• Alocasia
• Pothos
• Monstera
• Hoya

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