Common name: Trumpet Flowers

Incarvillea delavayi originates from central and eastern Asia, and is a deciduous clump-forming, upright hardy perennial, with Red, Pink, Yellow, or White petunia-like trumpet flowers.

The flowers appear in late spring / early summer.

Plants are not fully hardy in all parts of the UK, however applying a straw mulch after the plants die back should give ample protection in all but the worst of winters.

Incarvillea delavayi
in the border
Incarvillea delavayi
in close up

They grow to around 600mm (24") high with a spread of around 300mm (12"),and are suited to most types of soil provided it is well drained.

Having said that the best results are achieved where the soil is rich and relatively light, and is slightly acidic.

They grow quite well in partial shade, but full sun is better.

Plants should never be allowed to completely dry out during the growing season, so water them regularly during dry periods.


Week 9:

Sow seeds on the surface of pots or trays filled with seed compost, and germinate at a temperature of around 18°-21°C (65°-70°F)

Alternatively, sow in-situ and leave them to their own resources till the following spring, when they can be transplanted into their final quarters.

Germination can be sporadic, and can take anthing from one to ten weeks to germinate.

Week 13:

If large enough to handle, prick them out into individual 75mm (3") pots of potting compost.

circa Week 15:

Providing soil conditions allow, mature plants can be divided now if necessary.

Alternatively, wait till circa week 38-40.

circa week 20:

Once all fear of late frosts have passed plant young plants out 300-450mm (12"-15") apart in a prepared bed or border.

circa weeks 40-45:

Mulch the plants to protect the root system from hard frosts.

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