Germination temperature
18-24 °C (65-75 °F); keep below 27 °C (80 °F).
Flower growing guide
Stock germinates quickly in mild warmth and light, but it only flowers well after a spell of cool weather. This guide covers sowing, how to pick out double-flowered seedlings, and timing the crop for the cool season.
18-24 °C (65-75 °F); keep below 27 °C (80 °F).
On the surface or under a very thin layer of fine vermiculite.
About 7-14 days.
Light is essential for germination; do not bury the seed.
None for the seed. A short chill of the seedlings helps to tell doubles from singles.
Both work; cell trays make double selection and spacing easier.
Stock seed is small, flat and sown dry. Sow one or two seeds per cell so seedlings can be sorted and moved without root damage.
Not needed. The seed has no hard coat.
Not needed for germination. Cold matters later: young plants need several weeks of cool weather to start forming flower buds.
Not needed. Soaked seed is hard to spread on the surface, and stock needs to stay uncovered in the light.
Aim for 18-24 °C (65-75 °F). Below about 18 °C (65 °F) germination is slower and lower; above 27 °C (80 °F) both germination and seedling growth suffer, so in warm weather start trays in the coolest bright place available.
Sow on the surface of the compost and, if needed, cover with only a dusting of fine vermiculite that still lets light through.
A fine, free-draining seed compost. Stock prefers neutral to slightly alkaline conditions and does poorly in acidic soil.
Keep the surface evenly moist but not wet; a clear cover helps until germination, then remove it to reduce rot.
Stock needs light to germinate, so seed must stay at or very near the surface. After emergence give long days of bright light, such as 16 hours under lamps indoors, to prevent stretching.
About 7-14 days at 18-24 °C (65-75 °F); cooler compost slows it down.
In selectable strains, look at the seedlings once the seed leaves (cotyledons) have opened. Moving the trays to about 4-7 °C (40-45 °F) for a few days to a week makes the difference clear: double-flowered seedlings turn lighter, yellowish green, while single-flowered ones stay darker green. Keep the pale seedlings if you want doubles. In mixes that are not selectable, colour does not predict flower type, and singles are still fragrant and useful.
Plant out sturdy seedlings while they are young. Stock tolerates light frost, so it can go out early in the cool season. Close spacing of about 10-15 cm (4-6 in) gives single straight stems for cutting; give more room for bushy garden plants.
Plants need temperatures around 10-13 °C (50-55 °F) to start flower buds: about two weeks for early types and three weeks or more for late types. Plants that grow only in warm weather may produce leaves but no flowers.
Cause: the plants never had their cool period, usually because they were sown or planted too late. Fix: sow so that young plants grow through the coolest weeks of the year.
Cause: in stock, doubles are sterile and are always grown from seed of single plants, so a mix always contains a share of singles. Fix: use a selectable strain and sort seedlings by colour after a short chill.
Cause: grey mould (Botrytis), root and stem rots, and downy mildew in cool, wet, crowded conditions. Fix: water the compost, not the leaves, keep air moving, and remove affected plants.
Cause: stock is in the cabbage family and attracts aphids, caterpillars such as loopers, and flea beetles. Fix: check leaf undersides often and remove pests early.
Cause: heavy flower spikes and too much nitrogen. Fix: support rows with a layer of horizontal netting and feed moderately.
Stock declines when summer temperatures go above about 27 °C (80 °F) and dislikes hot nights. In most Indian plains it is a winter flower: sow at the end of the monsoon so that plants grow through the cool months and flower before spring heat. In hill areas it can be sown in spring.
Sowing several batches about two to three weeks apart gives a longer flowering season.
Cut spikes when the bottom third to half of the florets are open. Store cut stems cool and give them fresh water.
Six or more hours of direct sun gives the strongest spikes; light shade is tolerated.
Sow Stock Matthiola seeds for fragrant spikes through the cool season.
Double stock flowers are sterile, so seed always gives a mix of doubles and singles. In selectable strains, chill seedlings at about 4-7 °C (40-45 °F) for a few days after the seed leaves open: the lighter, yellowish seedlings are the doubles.
No more than a dusting of fine vermiculite. Light is essential for stock germination, so the seed should stay at the surface.
Stock needs a period of cool weather, around 10-13 °C (50-55 °F) for two to three weeks or more, to start flower buds. Plants grown only in warm weather often stay leafy. Sow earlier in the cool season.