Repotting guide

When & how to repot Spanish Wood Thyme (Thymus mastichina)

Also called Spanish wood thyme, Mastic thyme, Spanish marjoram, Herb mastic.

More about spanish wood thyme

About Spanish Wood Thyme

Thymus mastichina · also called Spanish wood thyme, Mastic thyme · herb

Thymus mastichina is an upright, bushy evergreen subshrub native to the Iberian Peninsula (Spain and Portugal), notable for its unusually strong, camphor-and-eucalyptus scent rather than the classic thyme fragrance of its relatives. It produces rounded clusters of small white flowers in summer on grey-green, softly aromatic stems and is widely used in Spanish cooking as a marjoram substitute. Perfect drainage and full sun are essential — this thyme is unforgiving of wet, airless soil conditions. The ASPCA lists thyme (Thymus) as non-toxic to cats and dogs.

Mature size: 25-40 cm tall by 40-60 cm wide (10-16 in × 16-24 in).

Watch for — Root rot from winter wet: Waterlogged soil — especially on clay in a wet UK winter — is the primary killer; plant in raised beds, on slopes, or in containers with drainage holes, and mulch with grit rather than organic material around the stem base.

How to tell spanish wood thyme needs repotting

Repotting on a calendar is less reliable than reading the plant. For spanish wood thyme, watch for these signs:

Roots growing out of the drainage holes, or the rootball lifting the plant proud of the rim.
Soil that has shrunk away from the pot sides and no longer holds water.
The pot is unstable because the plant has grown top-heavy.
Old, compacted, broken-down mix that stays wet too long — for a succulent that is a rot risk, so refresh it even if the pot size is fine.

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 spanish wood thyme

Every 2–3 years, into bone-dry mix. Spanish Wood Thyme's growth habit — upright, bushy, rounded evergreen subshrub — taller and more erect than most thymes. — sets the pace. Thymus mastichina is an upright, bushy evergreen subshrub native to the Iberian Peninsula (Spain and Portugal), notable for its unusually strong, camphor-and-eucalyptus scent rather than the classic thyme fragrance of its relatives. It produces rounded clusters of small white flowers in summer on grey-green, softly aromatic stems and is widely used in Spanish cooking as a marjoram substitute. Perfect drainage and full sun are essential — this thyme is unforgiving of wet, airless soil conditions. The ASPCA lists thyme (Thymus) as non-toxic to cats and dogs.

What size pot to step spanish wood thyme up to

Use a pot only one size up — or even the same pot with fresh gritty mix if the roots have room. Spanish Wood Thyme stores water and rots in a large pot of slow-drying soil. A tight terracotta pot that dries fast is far safer than a generous plastic one. Never up-pot a succulent by several sizes.

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 spanish wood thyme

Spring or summer, while spanish wood thyme is in active growth and warm, is best — roots recover fastest then, and the plant is not sitting in cool damp soil. Avoid repotting a succulent in winter dormancy.

Step-by-step: repotting spanish wood thyme

Repot dry. Do not water spanish wood thyme for several days first. Working with dry roots and dry mix dramatically lowers the rot risk for a succulent.
Pick a snug, fast-draining pot. Choose terracotta one size up at most, with a drainage hole. Have gritty sandy, gritty, or rocky, sharply drained ready.
Tip it out and clean the roots. Slide the plant out, crumble off the old soil, and trim any black, mushy or dead roots with clean snips.
Pot into dry mix. Set spanish wood thyme at its original depth in dry gritty mix, firming gently. Do not bury the stem deeper than it was.
Wait a week before watering. Leave it completely dry and out of harsh sun for about 7 days so any damaged roots callus. Only then water lightly.

Aftercare

Keep spanish wood thyme completely dry and out of fierce sun for about a week so any nicked roots callus before they meet moisture; watering a freshly repotted succulent is the classic way to rot it. Then resume the normal lean, dry rhythm. Do not fertilise for about 3 weeks — fresh mix already carries nutrients and feeding freshly disturbed roots scorches them.

The right soil mix for spanish wood thyme

Spanish Wood Thyme wants sandy, gritty, or rocky, sharply drained. Prefers poor to moderately fertile, slightly alkaline to neutral soil; rocky or stony soils that quickly shed water mirror its native Iberian scrubland habitat perfectly. Always use fresh mix when you repot — reusing old, broken-down soil reintroduces the compaction and poor drainage you are repotting to fix.

Repotting spanish wood thyme — frequently asked questions

How often should you repot spanish wood thyme?

Every 2–3 years, into bone-dry mix for spanish wood thyme. Repot spanish wood thyme every 2–3 years into a snug pot of sandy, gritty, or rocky, sharply drained, ideally in spring or summer. Let it sit in dry soil and do not water for about a week afterwards so any nicked roots can callus. Over-potting and watering straight away is what rots succulents.

What size pot does spanish wood thyme need?

When is the best time of year to repot spanish wood thyme?

Should you water spanish wood thyme after repotting?

No — not straight away. Repot spanish wood thyme into dry mix and wait about a week before the first watering so any damaged roots callus over. Watering a freshly repotted succulent is the single most common way to rot one.

Should you fertilise spanish wood thyme after repotting?

Not immediately. Wait about 3 weeks after repotting spanish wood thyme. Fresh mix already contains nutrients, and feeding freshly cut or disturbed roots burns them. Resume your normal feeding routine once you see new growth.