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Kent Alpine Gardener's Diary

This entry: 23 July 2014 by Tim Ingram


The summer is an important time for the propagation of many plants either from seed or cuttings. Gardeners who are interested in rarer and more unusual plants will inevitably be drawn to raising them from seed and for very many alpines and woodland perennials much the best thing, if possible, is to follow the natural cycles of sowing and germination from one's own collected seed. This time of year (and earlier) is the time to sow a lot of bulbous and woodland plants, and also some alpines where fresh seed can often result in rapid and good germination. The former two groups (and many other alpines which can be sown later into autumn and winter) in contrast usually don't germinate until the following winter and spring, and for woodland plants in particular later sown seed will quickly lose its viability.

These are two examples. We always collect as much seed as we can of Daphne retusa, which is such a fine garden plant but very slow to develop and make a sizeable plant in the nursery or garden. Fresh cleaned seed germinates well but not quickly, and although the plant can also be propagated quite readily from cuttings, the genetic variability from seed is always valuable.

The second example is Anemone obtusiloba, nothing more like a blue buttercup (sometimes actually soft yellow), which is native to the Himalayas and into Tibet. Seed of this matures rapidly on the plant but like hepatica is easily lost as it ripens and is still green. It must be sown fresh to get germination, and not all the achenes may fertilise and develop, as the second picture shows. Flowers are produced intermittantly over quite a long period so a regular watch for seed must be kept.

(Note: there is a very helpful thread on the SRGC Forum which illustrates seed of a great variety of plants grown by alpine gardeners, and helps to identify seed if the grower may be uncertain what they have from seed exchanges).

The third picture shows another reason for collecting seed - this is a distinct and interesting form of Triteleia ixioides that we have in the garden, anf hopefully will breed true from seed. Close up the blue anthers are especially striking.

We sow everything (except for fern spores and a few other more specialised plants) in a relatively standard JI seed compost - which should be fine and friable and made according to the original designation - supplemented with perlite or grit to improve drainage, and dependant on the size of the seed covered with a layer of fine chick grit (really fine seed takes a bit more care but can be sown on the surface of the grit and washed in with a fine sprayer - even tiny seedlings germinate well through fine grit like this. Rounded aquarium grit is also good but expensive). After sowing we soak pots from below overnight and then place in a shady open frame, which can covered from very heavy rain, or over winter when moisture levels are more constant. From experience this frame is enclosed with fine mouse-proof mesh, but generally only larger seeds like hellebores and umbellifers are so vulnerable to mice. The mesh also stops blackbirds from pecking out labels but unfortunately doesn't keep out slugs and snails which any resident frogs are unable to get too! Once seed germinates we generally bring it into a glasshouse where it can be watched more carefully.

Some fresh sown seed can germinate very quickly and these two examples are Soldanella carpatica sown at the end of May, and Pulsatilla halleri in early June.

Other seed, like Aquilegia ottonis amaliae which has become quite a favourite in the garden, was sown last autumn and really could do with pricking out now. There is a delicate art to this process which is greatly helped by having plenty of perlite in the compost, and sometimes by teasing seedlings apart under water to lessen damage to the roots.

Interestingly although I have usually tried to sow aquilegia seed (like so many of the Ranunculaceae) when reasonably fresh - i.e: in the autumn after harvest - we have had good germination from older (2012) seed of A. jonesii that we didn't get round to sowing until the same time last October. This seed came from Alan Bradshaw (Alplains), surely one of the most exciting of all seedlists, not with standing the Czech collectors and society exchanges. Whether we can grow this on and get it to flower is another matter!

Also from Alplains we sowed the Western US (Utah) shrub Garrya flavescens, after reading about it in Robert Nold's very informative and stimulating book 'High and Dry' (which is in the same tradition as the 'Jewels of the Plains' that I described last time, and incidentally includes a superb photograph of Claude Barr's Astragalus amongst descriptions of many other American dry-land species). The picture below is taken from this book. Can we find a good spot to grow this in the garden?

The excitement of growing plants from seed often comes first by reading about them in the AGS Bulletin and Journal or elsewhere, and way back in Vol. 1 there is a description and photo of Wulfenia baldacii, at that time a plant that commanded quite a lot of interest from growers.

I haven't grown this before but here is a potful of seedlings from the seed exchanges, sown in February. This genus is not often grown but is attractive, and the two pictures below are of the hybrid W. schwarzii growing in a shady corner of the rock garden at Kew. Originally classified in the Scrophulariaceae, and similar to Synthyris (but native to Europe rather than N. America), this has now been placed in the Plantaginaceae.

It is a little easier to see why Globularia incanescens should also be classified here, and this is a lovely and rare plant, perfect for a trough. Again it is exciting to get good germination of this from seed (in this case from the Czech traveller, seed collector and photographer Mojmír Pavelka - Euroseeds). No previous 'seed' I have had of this species has ever germinated. 

Individuals like these, and especially for British gardeners the late Jim Archibald, have an impact on gardens out of all proportion to their numbers because of the remarkable range of wild species they enable us to grow. For the botanically-minded gardener - who is such a feature of our specialist societies - the natural species and variation that arises from such seed can have greater importance than many horticultural 'improvements', and teaches a lot about the plants. On the other hand it can be equally exciting when hybrids arise in the garden, by accident or design. Our only claim to fame is Euphorbia 'Copton Ash', a putative hybrid between E. seguieriana subsp. niciciana and similarly named E. nicaeensis (actually quite distinct from the former). This arose in the garden and like both needs a warm and dry position to flourish [my grateful thanks to Derry Watkins - Special Plants -  who has given us a plant again after we had lost it in the garden].

(the 'Tea Bag' method)

(A quick addendum to this entry - please see Lesley Cox's description of this technique for stimulating germination, especially of hard coated seed like irises, on the SRGC Forum. There looks to be a sound scientific base for the technique and I wonder if anyone viewing this has experience of it too? This is something we will try in the future for seed we have found recalcitrant in the past)

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