Posted on May 1, 2009 by Ash
Before we get stuck in to the main course, would Reader like a starter? Another two seedlings were observed in the birch tray yesterday (Day 50), bringing the total to twenty-six. On top of that, a Set C first: two seedlings were discovered in sweet chestnut territory! But are they really sweet chestnut seedlings or just weed impostors? I’ve never seen a sweet chestnut seedling before, but I had a mental image of them being, uh, beefier. At least they’re not nettles…
Anyhoo, I was browsing the internet the other day when I came across a Forestry Commission Practice Guide entitled Raising trees and shrubs from seed (Gosling, 2007). “This could be relevant,” I thought, and relevant it is. As hoped, the guide provides advice on raising all three of treeblog Set C’s species from seed. It would seem I’ve not been going about things in quite the right fashion.
The Set C birch seeds. I collected them from an impressive tree on Whitwell Moor. Those catkins (more correctly “strobiles”) were chock-a-block full of seeds too.
According to the guide, birches are fairly easy to germinate. As “orthodox seeds”, birch seeds can be dried and stored for a long period of time. One of the recommended methods of storing birch seed (for no more than one winter) is to “Store in a loosely-tied polythene bag in the main compartment of a refrigerator (approximately +4°C)”. I kept my seeds in a plastic sandwich bag in my bedroom, which is obviously warmer than a fridge. The guide recommends either sowing in Jan-Feb to pretreat naturally or sowing in spring with or without artificial pretreatment. The recommended pretreatment here is to keep the seeds cold (about 4°C) for three to nine weeks (isn’t that just keeping them in the fridge a bit longer?). The guide classes this pretreatment of birch seeds as “Generally effective: a significant proportion of live seeds should germinate”
I pretreated my birch seeds by moving them into the shed for a few weeks before planting, and things seem to be going well. Twenty-six seedlings so far, a number I’d be very happy with if I knew for certain they were all birches. I actually sowed several hundred birch seeds, so only twenty-six seedlings looks like a poor rate of germination - but I don’t have anywhere to keep hundreds of birch seedlings!
The Set C sweet chestnuts. I collected them from a magnificent old tree at Wigtwizzle.
The guide devotes a paragraph to the curious phenomenon of “suicidal” seeds:
…some very small seeds, such as willow and poplar, and some very large fruits, such as oak, sycamore, sweet chestnut and horse chestnut, die quite soon after being shed from the tree – one of the last properties you would normally associate with seeds. The fruits are killed if they dry out and at present there is no known method of doing anything more than slowing down their rate of deterioration. It is therefore only worth collecting seeds of these species if you can sow them fairly quickly, or are prepared to suffer significant losses over, for example, one winter’s storage.
Great. It goes on to describe chestnuts as recalcitrant – highly perishable. One thing you can’t do is to let these things dry out: “if they are frozen or dried, they die”. I didn’t have anywhere humid to store my chestnuts, so I stuck them in the shed all winter. The air in the shed is certainly not as dry as that in the house, but I wouldn’t exactly call it humid. At least I didn’t put them in the freezer.
Still, there is some hope. According to the guide, if you store your freshly-collected chestnuts at low temperatures (3°C to 5°C) – to slow seed deterioration and minimise fungal growth – and high humidity – to retard drying – then you’ll only suffer 60-70% losses over a couple of years. Well, my nuts mightn’t have been kept humid, but they were kept cold (hopefully not too cold) and were only in storage for one winter, so at least some of them ought to still be viable. Later on, the guide warns that “sweet chestnut… will typically decline from 90% to 50% germination over the 10-24 weeks between collection in October/November to spring sowing in March/April”.
The good news is that while they are a pain in the backside to store, sweet chestnut, along with poplars, willows, oaks and horse chestnut, are the “easiest to germinate of all tree species”. No pretreatment is required.
If Set C, like Set B before it, fails to bear treeblog any young sweet chestnuts, then Set D will have to succeed! If it comes to that, then in the autumn, as soon as a new horde is collected, they shall be buried in compost and kept cool and moist all winter.
I collected these, the majority of the Set C rowan berries, from a tree on Whitwell Moor. A further eighty or so berries were collected from a tree near Upper Midhope.
So far it looks like I did okay with the birches, and I might yet scrape through with some sweet chestnuts, but how did I do with the rowans? Ha! terrible!
Rowan berries tend to contain two seeds, although they may hold more. I did not know this when I planted my rowans still in berry form - I thought they only had the one! Something I did think about but failed to act upon is this: rowan berries are eaten by birds; birds digest the berries; birds excrete the undigested seeds; the seeds then grow. How I wished for caged birds to eat my berries in a sort of controlled berry-digesting, seed-cleaning sweatshop. Alas! this just wasn’t practical and I didn’t fancy doing the birds’ job myself (what if I digested both berries and seeds?). In the end I simply planted the berries whole, which was a bit silly:
Fleshy fruits are also some of the most awkward and certainly the messiest to process. …very occasionally a little fermentation can help. However, for seeds such as hawthorn, holly and rowan, fermentation can be significantly harmful or even fatal and is therefore to be avoided. Subsequently, most seeds will need repeated washing not only to remove the clinging remnants of sticky flesh, but also as a means of removing chemicals that have the potential to inhibit germination.
Germination-inhibiting chemicals? Oh no! (At least rowan seeds, like birch seeds, are “orthodox” so can be dried and frozen for storage. My berries experienced the same storage conditions as my birch seeds.) Anyway, once your rowan seeds are nice and clean with no tarrying trace of berry, they can enter pretreatment hell. The guide describes pretreatment as “Only partially effective: even with the longest pretreatment durations and/or several pretreatment cycles”! Still, it recommends 2-4 warm (about 15°C) weeks and 16-30 cold (about 4°C) weeks of pretreatment. Awesome.
I think I’m going to have to exhume my rowan berries, release the seeds from their fleshy prisons, and replant. No time for pretreatment though. Maybe the next winter can be contracted to perform that job if nothing germinates before then?
Level of shame = high.
* * * * *
Raising trees and shrubs from seed is a great little guide. It provides a host of advice on collecting, preparing, storing and planting seed. You can download it free from here: http://www.forestry.gov.uk/pdf/fcpg018.pdf/$FILE/fcpg018.pdf
Posted in The treeblog trees
Posted on March 11, 2009 by Ash
Day 0 (Set C).
One hundred and one weeks since the planting of Set A and fifty-one weeks since the planting of failed Set B, I planted treeblog’s Set C today in a private garden ceremony. This latest set is represented by three species: rowan (Sorbus aucuparia L.), sweet chestnut (Castanea sativa Mill.), and birch (either silver (Betula pendula Roth) or downy (Betula pubescens Ehrh.)). Whereas a single tree provided me with all my chestnuts, and another with all my birch seeds, my rowan berries were collected from two different trees.
I collected these rowan berries from a tree at the edge of Whitwell Moor. I’ve been acquainted with this tree for a decade now and remember climbing in it during my days at high school. Here it is on the day of berry collection (26th September 2008):
This second lot of rowan berries, which are slightly smaller and more orange than the others, come from a
tree near Upper Midhope. I collected them on the 15th of last August, soon after it had sadly collapsed. I paid the fallen tree a visit three weeks ago and was glad to see it still in place and with live buds. Fingers crossed it can go on to see out a few more years. Here’s the rowan as it was on the 24th of August 2006, in all its former glory:
The birch seeds - which kept trying to blow away as I took this photo - were collected on the same day as the berries from the rowan on Whitwell Moor. The bulk of the seed, by the way, is still in the catkins in this photo. They were a pleasure to break up. The seed was produced by a great tree of amazing girth which is either a silver birch or a downy birch. I can’t quite make up my mind seeing as how it appears to have characteristics of both species. My suspicions are that it’s a silver birch that has been roughed up by the elements thanks to its exposed location at the edge of a wood on Whitwell Moor. If only I was in North America… From Wikipedia: “Many North American texts treat the two species as conspecific… but they are regarded as distinct species throughout Europe”.
The great silver/downy birch (26th September 2008):
My sweet chestnuts, the quantity of which gives me deep joy. These bad boys were collected from the Wigtwizzle Chestnut on not one, not two, but on three separate expeditions on the 5th, 9th, and 17th of last October. Primo! The Wigtwizzle Chestnut (seen below on the 7th of July 2007) is one of the most impressive trees in my local area. When you get close, the sheer size of this veteran’s trunk grabs hold of you and slaps your mind. It’s quite literally awesome. Chestnuts from this tree were also planted for last year’s Set B, but none of them germinated. However, I didn’t have that many, and they’d been kept in the house over winter which had probably dried them out beyond the realms of viability. This year the nuts were kept in a garden shed and I’ve got quite a few more.
Another (more aesthetically pleasing) view of those chestnuts.
The planting process was straightforward. I half-filled four seed trays with compost. Into one tray went all the birch seeds, into another went the Whitwell Moor rowan berries, into the third went half of the sweet chestnuts, and into the fourth went the rest of the chestnuts and the Upper Midhope rowan berries. All nicely spaced out likes. Then a light covering of more compost and a good watering.
The trays are now safe in the treeblog compound. Let the germination begin!
Posted in The treeblog trees
Posted on October 17, 2008 by Ash
(The photos in this post can be viewed at a higher resolution – click them to open their Flickr pages, then click the 'All sizes' button.)
treeblog’s grey alders sure have received a pasting from caterpillars this summer, No. 4 being the worst affected. Back in mid-August I posted a photo of a cluster of small translucent and green caterpillars on alder No. 1. Much bigger caterpillars are still munching away – I’m assuming that these are more mature specimens of the flavour photographed in August and not caterpillars of a different species. The four photos above were taken nearly three weeks ago on the 28th of September (the date of the last grey alder and Scots pine update) and show the big-size caterpillars. If anybody recognizes this species please email me at the address shown at the top of the page.
P.S. Earlier today... a third v. successful nut-collecting trip to that sweet chestnut!
Posted in The treeblog trees
Posted on October 10, 2008 by Ash
(The photos in this post can be viewed at a higher resolution – click them to open their Flickr pages, then click the ‘All sizes’ button.)
Sweet chestnuts. I have a desire to see sweet chestnut trees in the treeblog stables, and I know the perfect thoroughbred stallion to sire them. Last year, after jumping the gun a few times, I got hold of a tub of chestnuts from this hoss and planted thirty in March of this year for treeblog’s Set B. Not a single nut germinated. In fact Set B only produced one seedling, and that didn’t live very long. Set B was a massive failure.
2009 will be the year of treeblog’s Set C, and this time there will be sweet chestnuts. I’ve been back to the parent tree twice this week – on Saturday and Thursday – and I have collected a shed-load of nuts. I reckon I must have got about 150. So there is no way treeblog is coming away empty-handed in 2009. Set C is going to be sweet.
The chestnuts I gathered on my forays.
Posted in The treeblog trees