Physoplexis comosa in a pot sunk in sand in an alpine greenhouse
How to grow Physoplexis comosa from seed

Despite being a fascinating and much sought after alpine specimen, Physoplexis comosa is sadly rarely seen outside of botanical gardens and specialist nurseries.  Unlike many examples offered up as alpine plants in your local plant retailers, Physoplexis comosa is the genuine article native to the French and Italian alps. Commonly known as the 'Tufted Horned Rampion' or 'Devil's Claw', like all true alpines it has blooms characteristically larger than its foliage.

It is fairly easy to obtain Physoplexis comosa seeds online throughout the year. If growing under protection they can be sown at any time of year. If being started outside they will need to be sown under the protection of a cold frame in the autumn.

Outdoor germination

Fill a modular tray using a good quality, well-drained seed compost such as John Innes 'Seed and Cutting' Sow Physoplexis comosa seeds onto the surface at a rate of one seed per module. Cover the seed with a thin layer or horticultural grit, or vermiculite. Gently water in using a can with a fine rose on it so as not to disturb the seed then. Keep the soil moist but never waterlogged and avoid the compost drying out completely during germination. You now have two ways to proceed. The first is to place the modular tray in a cold frame, where the natural winter cold should offer ideal conditions for germination to occur in spring.

Indoor germination

The second is to place the tray inside a heated propagator 18-22°C for 2-4 weeks or seal inside a clear polythene bag and place it on a warm bright windowsill (but one which is out of direct sun during the hottest part of the day) for the same time period. As these seeds are grown under protection they will need an enforce period of cold stratification so they will next be moved to a refrigerator for 4-6 weeks at a temperature of approximately -4 to +4°C. After this period return to a temperature between 5-12°C for germination which although will have some variability should expect seedling emergence in up to 6 weeks.

Once the root systems have established in their modules the seedlings will be ready for potting on into 9cm pots, again filled with a well-drained compost. Avoid disturbing the root system and protected under glass before acclimatising the plants to outside conditions when danger of frosts have passed.

Physoplexis comosa will perform best in a gritty, well-drained, poor to moderately fertile alkaline soil in full sun. Be aware that it will need protection from winter wet. Physoplexis comosa can be successfully grown outside under suitable conditions or keep as a container grown specimen in an alpine house.

Image credit - Simon Eade

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