Geranium bohemicum

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Mid-winter still finds me busy with seed sowing, so I’ve chosen to post another older story about an annual geranium that I have to give a head start to, for our short growing season.

Although most of the Hardy Geraniums or Cranesbills are perennials, there are a few of the annual varieties that are an interesting addition to the garden. Of the annuals, the majority are weedy types and are not really garden worthy. Geranium bohemicum, although still a small plant, has an attractive flower and looks very nice in a forward position in a border or in the rockery (I have found that containers work the best in my conditions). It could reach 12 inches in height and has a somewhat sprawling growth habit (a little like G. thunbergii). The violet-blue flowers with darker veins are only about three quarters of an inch across but they can make up in volume what they lack in size.

G. bohemicum is a native of Europe and it shares the trait of being associated with sites of fires with our own native annual, G. bicknellii. The seeds can remain viable in the ground for years, and plants may appear after a forest fire or land clearing. I suspect that they would also keep for years using our standard seed storage practices. They are usually listed as being a biennial, but here in zone 4, I have never had them return for a second year. They would best be treated as an annual, and sown every year. The good thing about being an annual-type is that a lot of seed is produced, and there have been reports of them self-seeding. They might very well be biennial and self sow quite well in climates such as the British Isles. I would love to hear any comments about this, from the UK members.

I have tried sowing them three different ways. One method is to sow them indoors around March. Germination is good, but when it is too good, you wind up with a lot of plants to deal with while waiting for good weather to put them out. All geranium seed can be sporadic at germinating indoors, so you can also wind up with plants of varying age and size.

My second method is outdoor sowing direct in the ground (done in late fall) and that works as well. However, the two years I tried this method, the plants grew to about three inches in height, flowered at that size and that was it! They did not grow into the potential size that they should have reached. Perhaps in zones warmer than my zone 4 this may not be as much of a problem.

By far the most successful method was to winter sow the seed and allow it to experience the fluctuations of winter. If you have sown in a pot or planter, the new seedlings can be moved around the garden into prime positions of warmth and light in the spring, and this seems to give bohemicum the little extra that it needs to reach full potential. I keep my bohemicum containers in the unheated garage, so they germinate a little sooner than those stored outdoors, this also gives bohemicum a head start. So far I have used plastic planters, but I can imagine what a great candidate this plant would be for growing in hyper-tufa troughs.

Check out the seed exchange lists, as it is often offered. If you should grow this plant, check for seeds after the main blooming is over. They are ready to harvest when the ‘beaks’ turn brown and the seeds appear black.

I have received seed from an exchange this year of Geranium lanuginosum, which is said to be very similar to G. bohemicum. I look forward to seeing how close they are to each other.

• 25 Feb, 2014
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