Sunday, 11 June 2017

Two Madeiran Geraniums

Geranium maderense and Geranium palmatum.

Last year I decided to sow some geranium seeds and as is my habit acquired several species without really researching their cultivation although I did know that Geranium maderense was half-hardy. First I have to admit that neither of these plants is a well grown specimen, they both suffer from not being grown-on properly during their first year and have not attained the true stature of their species due to a combination of neglect and a degree of ignorance. There are far better specimens pictured on the internet should you wish to view them, but these, I hope, will suffice to illustrate the difference between the two similar and often mistaken species. 

Geranium maderense
 Hailing from Madeira, Geranium maderense is the Goliath amongst geraniums often attaining as much as 4' in both height and width and even larger. The Madeiran Cranes-bill or Giant Herb Robert is normally grown as a biennial but some authors describe it as flowering after three or four years either way it appears to be monocarpic although there are some references of it lasting as a short lived perennial, take your pick! My plant came from seed sown in early spring last year and unfortunately was the only one that the seed produced, probably because the seed was cold sown in the manner of its hardier relatives and would have benefited from a bit of heat. I left it in my poly tunnel over winter and due to the mild winter it survived. The pot it was in was too small which restricted its growth and probably contributed to the flower stems appearing early, I then realised what I had and brought it into the porch for safe keeping. Ideally the plant should be well fed and brought on quickly in its first growing year to establish a large crown supported by the leaf stems which grow downwards and form a support as other than this the whole thing is only supported by a woody tap-root. In my ignorance I cut off the dead leaf stems to "neaten it up" but this is a definite taboo which can result in the crown snapping off with the weight of the canopy.

Geranium palmatum
Hailing from Madeira but also known as the Canary Island Geranium, this species is slightly smaller than Geranium maderense but is often billed as a hardy perennial although I would discount this for my location without giving it winter protection and regard it as more suitable for cultivation in a cold house. This plant is the sole survivor from seven seedlings being the only one that wasn't pricked out early but left in the original pot as the "runt of the litter" all its siblings damped off which I think was related to the difficulty in transplanting due to the thread like tap root, if I was to grow either of these geraniums again I would consider sowing into cells one or two seeds at a time for ease of handling, even though the seed is very small it would be worth the extra effort. 

Differences:
From the pictures above it can be seen that Geranium maderense has finer foliage than the fleshier leaves of Geranium palmatum.

Geranium maderense
 Although in my ignorance I butchered them you can see how the leaf stems are meant to form a support for the woody tap-root.
 
Geranium palmatum
In the case of Geranium palmatum, although there is still a central woody tap-root the leaf stems grow almost horizontally.

Geranium maderense

Geranium palmatum
Although they both have typical geranium flowers and are very similar in colour Geranium palmatum has clear spacing between the petals.

I have described how not to grow these plants and hopefully indicated how it should be done, if you have a suitable spot in an area with mild winters, a cold greenhouse or a conservatory both are are worth a go as they do have a long flowering period and properly grown specimens, particularly of Geranium maderense, are spectacular. 


Primula x kewensis
Whilst on the subject of half-hardy plants another plant, from one of my favourite genera, which is best grown in a cold house or alpine house is Primula x kewensis. Raised at Kew from a cross between Primula verticillata and Primula floribunda it is a member of Section Floribundae and flowers during the winter months.

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