When to Repot Your Orchid (Part 2)

Now that you know how often to repot your orchid you may also wonder when.
Q: When is the best time to repot my orchid?

A:  At the start of a flush of new root growth.

Why?
Because an orchid establishes very quickly in a potting medium during the part of its annual growth cycle when its roots are actively growing. In nature that span usually coincides with the onset of the rainy season.

Many people are surprised to learn that tropical orchids have an yearly cycle of growth, flowering and rest--a cycle similar in some ways to the yearly growth cycle of temperate zone perennials, but more subtle. Orchid roots do not grow continuously throughout the year.

How do you know when a potted orchid is producing a flush of new roots? They are not always visible.
It's pretty easy, actually, to tell indirectly. Look for a new vegetative (leaf-producing) shoot on your plant. Most orchids produce new roots right around the time the new vegetative shoot appears. Think of the new shoot as a green flag signaling that it's time to repot. I have trained my eye to spot new shoots as I scan our orchid collection. When the new shoots are the size of my little finger, it's time to repot.

A new shoot on Laelia purpurata indicates that it's time to repot.

Is it bad to repot during those months when the orchid's root system is not growing?
It can be. If you damage the root system--and it's hard not to inflict a little bit of breakage during repotting--you can impair the orchid's ability to take up water. It could be months before new roots replace the broken ones. In the meantime your plant may start to decline.

Two new shoots on a Dendrobium Red Emperor 'Prince' that is ready for repotting.

A green flag: the new shoot of an Oncidium intergeneric at the start of its growing cycle. 

Be careful not to confuse a young flower spike and a new leafy shoot! Some orchids produce a flower spike that emerges near the base of a mature shoot--in the same neighborhood as the new vegetative growth. A young spike and a young leafy shoot can look very similar early in their development. If you're not sure it's best to wait. Within a couple of weeks it should become obvious.

What about orchids like Phalaenopsis (above) that don't produce a new shoot? When do I repot my Phalaenopsis?
The best time to repot Phalaenopsis (and other monopodial orchids) is within a month or two after flowering.

Coming soon: a review of commercial potting mixes for orchids.

When to Repot Your Orchid (Part 1)

Q: When should I repot my orchid? Does it matter when?
 Absolutely!

However, there are two ways of interpreting when:
Frequency How often does an orchid need to be repotted? and
Timing During which stage of the orchid's annual growth cycle should repotting be done?

The next two posts will address these questions separately. Today's post tackles the first: How often should I repot my orchid?

You don't need to repot your orchid every year. At the Fuqua Orchid Center we strive to repot our orchids every two years as a general rule. But that is just a general rule. Sometimes one or three years is more appropriate. When I am evaluating our plants with regard to repotting there are always three questions I ask:

1. Is the orchid about to overgrow its pot?
The Oncidium intergeneric (above) has two new shoots (pointing leftward). They look fine now, right? But imagine how they will look next year at this time in the same pot when those two shoots have matured into fat round pseudobulbs. Pretty crowded. Now is the time to repot!

2. Has the orchid's health declined (shriveled pseudobulbs, wrinkled or yellowing leaves) or has it overgrown the side of the pot?
The Laelia (above) should have been repotted two years ago. Yikes. If we wait another year it will be in a serious state of decline. As it is, this plant is so overgrown that it needs not just repotting, but dividing as well--major surgery which could have been prevented had we repotted it in a timely fashion. This plant needs emergency intervention!

Cattleya Mix. Brand new (left) and after two years (right).

Premium Sphagnum Mix. Brand new (left) and after two years (right).

3. Has the potting mix broken down?
Question 3 is especially important. The quickest way to kill your orchid is to let the soil mix break down. Here's what you need to know:

• Most orchids available commercially are tropical in origin, and the majority of tropical orchids are, in varying degrees, epiphytic--they live in trees. Their roots are often exposed to brief drenching rainfall, wind and drought on a daily basis. They are not covered in wet soil.
• In cultivation orchid roots need a potting mix that allows some air circulation. That's why the best orchid mixes are chunky and coarse in texture.
• A high quality orchid mix--either the classic bark/charcoal/perlite type or the newer premium sphagnum variety--lasts about two years, depending how much warmth and moisture it is subjected to.
• Over time bark and sphagnum break down, and if watered at the same rate they become increasingly waterlogged. Ask yourself: Does the mix take a lot longer to dry out than it used to? Is the moss now dark brown or covered with green moss? Is the bark soft and crumbly and dark brown? Time to replace it!
• A constantly saturated potting mix will kill your orchid.

The bottom line: repot your orchid about every two years.

A 'yes' answer to any of the 3 questions above means that your plant is a good candidate for repotting. But maybe not immediately! In order to time your repotting correctly, see my next post.