Pollen and nectar (crocuses)

[Hartwig]

Dear experts,

I'm new in this exciting forum and have already gathered a lot of valuable information, in particular related to the genus Crocus. I have been searching for a while on information regarding pollen and nectar in different crocus species, as one of my interests is bumblebee-conservation and offering appropriate flowering plants for bumblebees and other wild bees.

Crocuses cultivated in gardens are often the first source of nectar for bumblebee-queens emerging from hibernation in early spring. Unfortunately, precise information on eligible species offering a high level of nectar is not available from providers of corms, even though some commercially available packages are labeled "bee-friendly".
Searching the literature (Bowles, 1955; Matthew 1982; Ruksans 2010) information on this topic is also scarce.

Therefore, please allow to address this question to the community of crocus-experts: Is there any information out on the variable offer of nectar (+/- pollen) of the diverse crocus-species/cultivars or any information on preferred pollinators of different species/cultivars?

In other words: What would be in your opinion the "ideal" spring-crocus, hardy enough to survive in gardens (in particular in Northern Germany, 21m above sea level) and serving as the best source of nectar for bumblebees (and other wild bees) emerging in the late March-/early April timeframe?

Any guidance from you would be greatly appreciated!

Thanks in advance,

best regards

Hartwig

PS: Having initially approached the topic "crocus" from another angle, I however become more and more fascinated about this wonderful genus by itself the more I gain insights ...

[Maggi Young]

Greetings, Hartwig - welcome to the forum.

I agree, many of us here are in thrall to the fascination of Crocus from many aspects.

From our situation here in North East Scotland, I would suggest that almost any of the C. chrysanthus cultivars is a hardy candidate for reliable flowering and an opportunity for pollinators to have early access to  flowers.

[Thomas Huber]

Welcome Hartwig.

Maggi's hint for Crocus chysanthus is a useful tipp, but you have to consider, that many of the chrysanthus cultivars have defective anthers which do NOT produce reliable pollen. These are among others: Fuscotinctus, Dorothy, Cream Beauty, Romance, Prins Claus, Snowbunting, Skyline, Aubade..... unfortunately these plants are often used for mixed bags of Crocus chrysanthus, because they have an outstanding increasing rate which makes them very worthy for mass growing. If you want to use these colourful plants for bumblebees you should try to avoid these plants with defective anthers and look for all the other plants available in the garden centers like: Miss Vain, Ard Schenk, Advance, Blue Pearl, Goldilocks, Herald, Zwanenburg Bronze....

You could also try Crocus tommasinianus and its cultivars. I have observed, that some of them (Eric Smith, Whitwell Purple, Ruby Giant) don't set seeds, but at least they produce pollen. Others are: Albus, Roseus, Lilac Beauty, Barrs Purple.

Also Crocus vernus and its cultivars are useful even if they flower 3-4 weeks later than chrysanthus and tommasinianus.

Don't know where in the North you live, but I'm sure you know the crocuslawn in Husum. This is Crocus napolitanus from Italy, another plant from the vernus series. Unfortunately this form isn't available in trade 

All these crocus planted together should give your bumblebees pollen from January/February until the beginning of April and are hardy in German gardens.....and maybe you can add some snowdrops and Eranthis, too.

Good luck !

[Maggi Young]

 
See, Hartwig, I knew our experts would arrive with great advice!

[Hartwig]

Dear Maggi and Thomas,

thanks so much for your welcome and for the very valuable advice. This is greatly appreciated and exactly what I have been looking for!

Thomas' detailed information on the respective cultivars with defective anthers is of course important as I expected genetic alterations in several cultivars (spontaneous mutations) leading to defects in the reproductive system of these plants and therefore making them sterile. A sterile plant has "no reason" to attract and reward pollinators, so it might also be possible that the cultivars not reliably producing pollen as outlined by Thomas also may not produce any nectar.

The "positive-list" is a perfect guidance and I'll follow your advice on the respective recommended Crocus crysanthus cultivars, tommasinianus and vernus. And if you don't mind I'll cite your advice in the accordant thread of our German bumblebee conservation-forum (http://aktion-hummelschutz.de/forum/thread.php?threadid=1100&threadview=0&hilight=&hilightuser=0&page=1), so this valuable information will also be availble to my fellow bumblebee-conservationists.

Yes, we know the famous crocuslawn in Husum; we live close to the city of Lübeck, but Schleswig-Holstein is a very small federal state and different locations can be easily reached from any starting-point.

In our garden we also grow several Galanthus and Eranthis species, on the latter several wild bee-species are often seen foraging in early spring. Snowdrops - at least ours - have never been visited, maybe we also have grown some sterile cultivars ...

Thanks again and best wishes,

Hartwig

[Hartwig]

... just one addition. As Thomas mentioned Crocus napolitanus not being available for trade, I found this species in the webshop of this Dutch seller while searching for offers of the recommended bee-friendly species/cultivars: http://www.atouchofgreen-gardenwebshop.nl/nijssen-voorjaarzomerbloeier-crocus-c-96_26_3140_3168.html?page=2&sort=3a

Unfortunately, it is already sold out  , but you might earmark this offer for 2015.

Best wishes,

Hartwig

[Maggi Young]

..................but you might earmark this offer for 2015.

 good idea, thanks!