Cork oaks: assessing winter’s damage

Winter has been long and fickle this year. Mainly, I’d say, it’s been drier and colder than usual, with fewer storms. But between the cold periods there have been unseasonably warm spells (up to 20C); between the dry spells there have been huge rain storms; and between the calm spells there have been some ferocious and freezing winds. Tipyn o bopeth (a bit of everything) really and quite challenging in the garden.

The young cork oaks (which are now two and three years old) have mainly suffered from the tortrix moth caterpillars, as per usual.

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Tortrix moth caterpillar damage on cork oak

But in addition, they have also been being eaten by some kind of leaf miner…

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Leaf miner and freeze damage on cork oak

and the younger trees have suffered a little from the lack of moisture and freezing winds – showing in the orangey-bronzey tints you can see  in the picture above, alongside the dull buff colour where the leaf miners have stripped the living cells.

However, I’m happy to say, that they all seem to have come through OK and have plenty of new buds for this year’s growth. Hopefully winter will soon go away and they can put on some strong new growth through the summer.

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Tassels!

This beautiful little tassel tree (Garrya elliptica) was bought last autumn. It’s only a baby, and possibly it shouldn’t have been left to flower so prolifically. But it looks just beautiful, especially now the sun is shining.

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Tassels (male flowers) on a baby tassel tree (Garrya elliptica), January 2017

The tassel tree, or silk tassel tree, grows to around 4m tall with a similar spread – so it’s more like a big shrub really.

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Through the tassels

Tassel trees are mainly grown for their attractive catkins (tassels) that brighten up the darkest time of winter. Incidentally, the male and female catkins are borne on separate trees: you want a male tree for the best catkin display. These trees are also quite hardy, down to about -10C, but like all plants, they’re more tender when they’re young.

(The blotches you can see on the leaves are most probably fungal and came with the plant from the nursery. It was over dry and overly pot bound, meaning it was stressed and consequently vulnerable to infestations / infections. Hopefully in the coming year with a bit of pruning and good watering and feeding it will grow away from the fungal infection.)

Growing carob trees from seed – 18 month update

Last week, I put the carob trees, planted in the spring of last year, back into their cold frame for the winter.

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Carob trees at 18 months

Of the seven pips that germinated, all have survived (hooray!). Two are definitely thriving; two are doing ok; and two have suffered quite severe knock backs.

Of the two that have suffered the most, one was badly affected by tortrix moth caterpillars (the main and only noteworthy pest I’ve noticed with these trees). The other one was badly damaged by sun scorch – yes, even here in north Wales!

Through the summer, the little trees have been out against a south facing fence with a little bit of shade from various shrubs. Early on in the summer, we had some unseasonably hot and very sunny days. And on one of those days, the tree which had been growing the best was scorched – it was on the edge of the group and had the least shelter from the shrubs’ shade. That sun-blast caused all this year’s growth on that tree to die back.

But, I’m not giving up on it. These are tenacious little trees. Even the one that had been pulled up by the birds and looked to be a complete disaster is still trying to grow (it too has been badly bothered by the pesky tortrix moth caterpillars).

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The “runt” of the carob family: it’s been pulled out by birds and attacked by caterpillars, but it’s still putting out new shoots.

Two things I have learnt, and they’re both a bit of a surprise: the trees like a lot of water (but also good drainage); and they prefer to be in shade, not full sun (which makes sense for a baby tree really). I’ve also noticed that they grow best when there are weeds in the pot. I can’t really figure that out, but it’s something quite common with potted plants. Consequently, when I repotted the sun damaged tree, I deliberately planted some weeds in with it to keep it company:)

A Strawberry Tree – Arbutus unedo

From time to time, I feel the need to acquire a specific plant. A few weeks ago, for no particular reason, I began to think it would be nice to have a strawberry tree (Arbutus unedo). I see these trees often in Portugal, and there are even a couple of straggly specimens growing wild quite local to me here in Wales, but it’s not a tree I’ve often seen in local nurseries or garden centres.

The idea became fixed in my mind that a strawberry tree would be just the thing for me, and so I went in search of a young tree.

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Strawberry tree (Arbutus unedo) flowers

I was surprised and delighted to find a neglected specimen tucked away at a local nursery. Its pot was thickly covered with moss and liverworts and it was so pot bound that I had to cut the pot to extricate it. It’s now being mollycoddled for the winter before I’ll plant it out next year.

Strawberry trees flower very late in the year – October to December-ish. And, if the flowers are pollinated, the fruit (the so-called strawberry) will develop over the course of the next year so that fruits and flowers are both on the tree at the same time. It’s evergreen and will develop a lovely rich-reddish coloured shaggy bark as it gets older. It grows only slowly and will never grow to be super big, so it’s an ideal tree for a sheltered, medium-sized garden. Fingers crossed that my little rescue-tree revives and thrives.

(I found that the website of Waterlow Park in London had a nice page exploring the history and controversies surrounding the strawberry tree.)

Growing carob from seed

I love carob trees (Ceratonia siliqua) and, having had some success with growing cork oaks from seed, I decided to have a go with carob seeds too.

I brought two big carob pods back from Portugal in November last year and then – because I’d read that you shouldn’t sow the seeds until the spring – I left them in a cupboard for the rest of the winter .

In the spring (12th March to be precise) I cracked open the pods and picked out the seeds. One pod was totally empty, but the other yielded eight seeds.

I’d read that you need to sand the seeds and soak them in boiling water prior to planting them, but I was too timid to do that. Instead, I put them into a cup of hot water – 50% boiling: 50% cold – and left them for 24hrs.

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Carob seeds soaking in warm water prior to planting

The next day, I popped each seed into a small peat pot (so-called, they’re not actually made of peat, but other plant fibres) filled with a mixture of sand, general purpose compost and vermiculite.

To be honest, because I’d read so many doom and gloom stories about the seeds having low viability, low germination rates and generally being super-tricky to grow, I didn’t hold out too much hope for mine. I put the pots outside, but sheltered by a sheet of glass, and I kept them moist (sometimes I admit they did get a bit dried out, that’s a problem with peat pots).

I was amazed when, after less than two weeks, strong roots started growing through the sides and bottoms of one pot after another. At this stage, there were still no signs of growth on the surface – it was all going on underground. I quickly put each peat pot into a larger plant pot filled with the same compost/sand/vermiculite mix. Within a month of sowing, the cotyledons started to poke their heads out in each pot. The slowest one was about three weeks behind the fastest in making its appearance.

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Carob cotyledons emerging four weeks after planting

And since then, the little carob trees have been growing on in their pots. Of the eight seeds I sowed, seven germinated and grew to produce true leaves. Of those seven, six are still doing fine; one was pulled from its pot – probably by a bird – and by the time I found it it was quite wilted. That one is still growing, but it is very stunted.

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The first true leaves emerging in the second week of May – about eight weeks after planting.

Now that winter is here, I’ve moved the little carob trees (they’re between four and five inches tall) into a cold frame. They’re supposed to be hardy to about -8C (17F) which we’re unlikely to see here, but it’s not impossible. Mainly I’ve put them in the frame to keep their soil dry-ish through the winter.

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One of the little carob trees, nine months after planting.

So, that’s my experience of growing carob from seed: so far, so good:)

 

It’s raining birch seeds

It’s warm and dry today with no rain forecast, but in the garden there is a constant pitter-patter amongst the trees. It’s the sound of birch seeds falling – helped along by goldfinches and siskins who are tugging at the catkins to pull out the seeds.

Through the canopy, a constant stream of tiny birch seeds are falling down.
Through the canopy, a constant stream of tiny birch seeds are falling down.

Continue reading “It’s raining birch seeds”

Growing cork oaks from seed

In 2013 I was given three cork oak (Quercus suber) acorns to try growing.

The first cork oak seedling after one year's growth
The first cork oak seedling after one year’s growth

At the time, I was in the middle of bulb planting and I popped the three acorns into individual 9cm pots without much thought. That was at the start of December.

I was amazed when about a month later the compost in the pots started to heave, indicating that things were stirring underneath. I was more amazed when I went out one morning and found a hole where one of the acorns had disappeared completely from the pot. I don’t know who stole it – possibly a magpie. My lesson learnt, I covered the two remaining pots with pea netting to stop further thefts.

I then started reading about how to grow cork oaks from acorns: obviously, I should have done the reading first:) I learnt that I should have simply laid the acorn on the soil/compost and sprinkled a little more over the top – replicating what would have happened naturally. I hadn’t done that: I’d dibbed a hole and pushed the acorns quite deep (I blame it on the bulb planting frame of mind). And I should have used tall pots to allow long tap roots to grow.

So, I decided to tip out my two acorns and replant them with more soil beneath – for their long tap root – and less above – to let them reach the light quickly and easily. In so doing, I damaged the roots of one of the seedlings and it never recovered. Happily, despite all my maltreatment, the other one grew and grew. When it was about four inches tall, I planted it into the garden. Now, at just over a year old, it is just under a foot tall.

Last December, I decided to try again and to do things more correctly this time. I laid four acorns in tall pots (the kind usually used for raspberry canes and the like) containing a mixture of coir, multipurpose compost and garden soil, and I sprinkled a little more of the mixture over the top.

Cork oak shoots - this is about four months after planting
Cork oak shoots – this is about four months after planting

Initially I kept these pots out of doors, but with a propagator lid over them to prevent thieving birds and also to stop them getting too wet in our long damp winter.  Once the acorns started “moving” (germinating) I covered the pots with pea netting and got rid of the lid.

So far, two of the acorns have germinated properly and have sturdy young growth. Another one started to germinate, but I think it might have failed as it is a while since anything happened. The other seems to still be progressing, but very slowly: there are signs of root growth, but no shoot yet.

Clearly I can’t really draw any conclusions from such a little experiment, but it would seem that cork oaks are pretty easy to grow from acorns. The main things to watch out for are: thieving birds and rodents; to make sure that the pot you choose has sufficient space to let the acorn “move”; and to choose deep pots to let the tap roots grow. It’s also important that the acorns you use are fresh – plump and shiney, not crinkled and dull.

Cork oaks are relatively hardy, they can survive temperatures down to around -10C (depending on whose description you read – it may be a bit lower or higher than this) and they make beautiful trees as they mature.