Ever since I first saw a photo of Eryngium leavenworthii in the Thompson & Morgan catalogue I knew this was a plant I just had to grow. Eryngiums are generally beautiful plants and all the better, in my mind, for frequently being spiny. I like plants that can look after themselves if they need to – probably why I like cats too! Eryngiums or sea hollies (only one really grows by the sea) are in the carrot family (Apiaceae) and are either perennial, biennial or, as in this case, annuals. Unlike salvias, where the New World species are the most exciting to me, it is the Old World eryngiums that get my pulse racing, in general. The Central and South American species, although they have exciting rosettes of foliage, lack floral appeal, even though the flower heads are numerous. They lack the colour and showy floral bracts of the Old World species. But this Texan is a real show stopper.

It is an annual native to western Texas and can grow up to 1.2m. What makes it really special is the colour of the flowers heads which is bright, metallic purple. The flowers and the bracts are the same shade and, just to make it extra special, the heads have a topknot of bracts rather like a French lavender. Add to that the blue stamens that stick out of the flowers and you have a very special plant.

Now my plants have been living on the edge and have developed slowly and, if we had not had a fine, warm September I don’t think I would be gushing quite so effusively over this plant because it has been a very late developer. I think it is largely down to me not quite understanding its needs but I will know in future.

I started the seeds in March and germination can be a problem. I think it is one of those seeds that, like cleomes, needs a variation in night and day temperature to germinate. Keep it moist and warm at all times and I think it will struggle to germinate. I kept it as warm as I could for a few weeks but then took it out of the propagator and in the ambient greenhouse temperatures it eventually produced some seedlings but still at least a month after sowing. These were transplanted to cell trays, to grow on, when they were small and they were planted out in late May.

They were very straggly and miserable at first. I made the mistake of planting them with other ‘everlastings’ such as rhodanthe and xeranthemum and these rather swamped the eryngiums. But not only did they grow more quickly, they went over fast too and the eryngiums finally got more light. The spot I chose for them was extra well drained but it was also shadier than I had at first realised. So although the straggly stems grew, to about 30cm high, there was not much sign of flowers till late August. I kept my fingers crossed for sun! We did get sun. And I have got flowers. The branching stems all have at least 10 flower heads developing and those growing among the panicum ‘Frosted Explosion’ are doing best and this is a combo I will repeat next year.

I am hoping the flower heads will dry well and retain their colour when dried. This year has been a learning curve and now I know the plant better I hope to have much better plants next year. It is certainly a plant I want to get to grips with and have lots of next year.

Geoff’s rating 8

Garden rating 6

By the way, the seed is often sold as the cv ‘Purple Sheen’ but I don’t think this is  different to the species but is just a selling name.

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