Repotting guide

When & how to repot Sander's Maxillaria (Maxillaria sanderiana)

Also called Sander's Maxillaria, Queen of the Maxillarias.

More about sander's maxillaria

About Sander's Maxillaria

Maxillaria sanderiana · also called Sander's Maxillaria, Queen of the Maxillarias · tropical

Maxillaria sanderiana, known as the Queen of the Maxillarias, is a large, cool-growing epiphytic orchid from cloud forests of Ecuador and Peru, bearing magnificent large solitary flowers — white with bold crimson and yellow markings — in summer to early autumn. One of the most spectacular in the genus, it demands cool nights, very high humidity, and bright filtered light; ideally grown in a cool Andean-climate greenhouse.

Mature size: 50–80 cm tall; individual flowers 12–15 cm across

Watch for — Fungal leaf spot and rot at high humidity: The warm-moist combination required by this species also favours Fusarium and Botrytis. Ensure constant air movement with fans (oscillating fans work well in greenhouses). Remove any yellowing or spotting leaves immediately and treat with a preventive copper or mancozeb fungicide.

How to tell sander's maxillaria needs repotting

Repotting on a calendar is less reliable than reading the plant. For sander's maxillaria, watch for these signs:

Roots poking out of the drainage holes or coiling visibly around the inside of the pot.
You are watering far more often than you used to because the rootball dries out within a day or two.
Water runs straight through and out the bottom without soaking in.
Top growth has slowed or new sander's maxillaria leaves are noticeably smaller than older ones despite good light.

For the underlying biology of a pot-bound root system and why it stalls a plant, see our guide to spotting and fixing a root-bound plant.

How often to repot sander's maxillaria

Every 12–18 months — sooner if roots show fast. Sander's Maxillaria's growth habit — sympodial epiphytic orchid with large, ovoid pseudobulbs spaced on a short rhizome, each bearing 2–4 long, leathery strap leaves. single, large, showy flowers arise from peduncles at the pseudobulb base during summer. — sets the pace. Maxillaria sanderiana, known as the Queen of the Maxillarias, is a large, cool-growing epiphytic orchid from cloud forests of Ecuador and Peru, bearing magnificent large solitary flowers — white with bold crimson and yellow markings — in summer to early autumn. One of the most spectacular in the genus, it demands cool nights, very high humidity, and bright filtered light; ideally grown in a cool Andean-climate greenhouse.

What size pot to step sander's maxillaria up to

Step up one pot size — about 2–3 cm (an inch) wider. Sander's Maxillaria grows fast, so it will fill that space within a season, but jumping several sizes at once still backfires: the unused soil stays soggy and rots even a vigorous root system. One size at a time, every year or so, is the rhythm.

Not sure of the exact diameter? Our pot size calculator takes the current pot and root spread and tells you the right next size — it deliberately recommends a single step up, never a big jump.

The best time of year to repot sander's maxillaria

Early spring, just as new growth restarts, is the ideal window for sander's maxillaria. The plant is moving into its strongest growth phase and re-roots into fresh soil quickly. Avoid repotting in winter dormancy or, for flowering plants, while it is in bud or bloom — recovery is slowest then and you risk dropping the flowers.

Step-by-step: repotting sander's maxillaria

Time it for spring. Repot sander's maxillaria in early spring as growth restarts so it re-roots quickly into the fresh soil.
Choose one size up. Pick a pot about 2–3 cm wider with drainage holes. One step only — a much bigger pot stays soggy and rots roots.
Ease the plant out. Water lightly the day before, then tip sander's maxillaria out and gently loosen any roots circling the bottom of the rootball.
Repot at the same depth. Put a layer of fresh open bark, perlite and sphagnum mix; or mounted on cork in the new pot, set the plant so its soil line is unchanged, and backfill, firming lightly.
Water and pause feeding. Water once to settle the soil. Hold off fertiliser for about a month — fresh mix already has nutrients and feeding now burns new roots.

Aftercare

Water sander's maxillaria once to settle the soil, then let the surface dry before watering again — fresh mix around the roots stays wetter than the old compacted ball, so the commonest post-repot mistake is overwatering. Keep it out of direct sun for a week or two while roots re-establish. Do not fertilise for about 4 weeks — fresh mix already carries nutrients and feeding freshly disturbed roots scorches them.

The right soil mix for sander's maxillaria

Sander's Maxillaria wants open bark, perlite and sphagnum mix; or mounted on cork. Use a very open mix: medium fir bark, coarse perlite, long-fibre sphagnum (3:1:1). Alternatively, mount on large cork bark panels or tree fern slabs with sphagnum at the root zone — this prevents root rot while maintaining moisture. Mounted specimens need daily misting. Always use fresh mix when you repot — reusing old, broken-down soil reintroduces the compaction and poor drainage you are repotting to fix.

Repotting sander's maxillaria — frequently asked questions

How often should you repot sander's maxillaria?

Every 12–18 months — sooner if roots show fast for sander's maxillaria. Repot sander's maxillaria roughly every 12–18 months, in early spring as growth restarts. It grows fast and circles its pot quickly, so step up one size (about 2–3 cm wider) into fresh open bark, perlite and sphagnum mix; or mounted on cork. Don't jump several sizes — that soggy excess soil is what rots vigorous roots.

What size pot does sander's maxillaria need?

When is the best time of year to repot sander's maxillaria?

Can you put sander's maxillaria straight into a much bigger pot?

No. Even a fast-growing sander's maxillaria should only go up one pot size at a time. A vastly oversized pot holds a reservoir of wet soil the roots cannot reach, which stays cold and soggy and rots the roots — the opposite of what you wanted.

Should you fertilise sander's maxillaria after repotting?

Not immediately. Wait about 4 weeks after repotting sander's maxillaria. Fresh mix already contains nutrients, and feeding freshly cut or disturbed roots burns them. Resume your normal feeding routine once you see new growth.