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Repotting guide

When & how to repot Sea Stock (Matthiola sinuata)

Also called Sea stock, Wild stock, Sinuate stock.

More about sea stock

About Sea Stock

Matthiola sinuata · also called Sea stock, Wild stock · flowering

Matthiola sinuata is a biennial or short-lived perennial native to sandy coastal cliffs and dunes along the Atlantic coast of Europe and the Mediterranean, characterised by silvery, wavy-margined grey-green leaves and spikes of intensely fragrant lilac to pale purple flowers whose scent intensifies at dusk. It demands full sun, sharply drained, light sandy soil, and good air circulation, mirroring the open coastal habitats where it grows wild. Excellent salt and wind tolerance makes it ideal for seaside gardens, but it will not survive in heavy or waterlogged soil. Stock flowers (Matthiola) are considered non-toxic to cats and dogs.

Mature size: 30–60 cm tall, 20–40 cm wide.

Watch for — Clubroot (Plasmodiophora brassicae): As a Brassicaceae member, sea stock is susceptible to clubroot in infected soils, causing wilting and swollen root galls; grow in well-drained, slightly alkaline soil and rotate planting positions annually.

How to tell sea stock needs repotting

Repotting on a calendar is less reliable than reading the plant. For sea stock, watch for these signs:

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 sea stock

Every 2–3 years, into bone-dry mix. Sea Stock's growth habit — biennial or short-lived perennial forming a basal rosette of sinuate (wavy-edged), grey-woolly leaves in year one, then sending up erect fragrant flower spikes in year two. — sets the pace. Matthiola sinuata is a biennial or short-lived perennial native to sandy coastal cliffs and dunes along the Atlantic coast of Europe and the Mediterranean, characterised by silvery, wavy-margined grey-green leaves and spikes of intensely fragrant lilac to pale purple flowers whose scent intensifies at dusk. It demands full sun, sharply drained, light sandy soil, and good air circulation, mirroring the open coastal habitats where it grows wild. Excellent salt and wind tolerance makes it ideal for seaside gardens, but it will not survive in heavy or waterlogged soil. Stock flowers (Matthiola) are considered non-toxic to cats and dogs.

What size pot to step sea stock up to

Use a pot only one size up — or even the same pot with fresh gritty mix if the roots have room. Sea Stock 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 sea stock

Spring or summer, while sea stock 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 sea stock

  1. Repot dry. Do not water sea stock for several days first. Working with dry roots and dry mix dramatically lowers the rot risk for a succulent.
  2. Pick a snug, fast-draining pot. Choose terracotta one size up at most, with a drainage hole. Have gritty sandy, well-drained, alkaline to neutral ready.
  3. 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.
  4. Pot into dry mix. Set sea stock at its original depth in dry gritty mix, firming gently. Do not bury the stem deeper than it was.
  5. 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 sea stock 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 sea stock

Sea Stock wants sandy, well-drained, alkaline to neutral. Thrives in light, open coastal sands with low organic matter; a gritty, free-draining compost suits container growing — never plant in heavy clay or enriched, moist beds. Always use fresh mix when you repot — reusing old, broken-down soil reintroduces the compaction and poor drainage you are repotting to fix.

Repotting sea stock — frequently asked questions

How often should you repot sea stock?

Every 2–3 years, into bone-dry mix for sea stock. Repot sea stock every 2–3 years into a snug pot of sandy, well-drained, alkaline to neutral, 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 sea stock need?

Use a pot only one size up — or even the same pot with fresh gritty mix if the roots have room. Sea Stock 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. Use our pot size calculator to size it from the plant's current pot and root spread.

When is the best time of year to repot sea stock?

Spring or summer, while sea stock 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.

Should you water sea stock after repotting?

No — not straight away. Repot sea stock 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 sea stock after repotting?

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

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