Wednesday, August 24, 2011

Decisions, decisions, decisions

Euphorbia mellifera is one of the mainstays of the exotic garden here in the UK.  It rapidly forms a  large, rounded shrub with attractive linear foliage with a white central vein and long lasting, late spring heads of honey scented flowers.

Euphorbia mellifera with Cordyline 'Coffee Cream in 2005
Euphorbia mellifera flower heads and foliage

Euphorbia mellifera flower head close up
As a fast growing plant it can get out of hand fairly quickly.  2-3ft / 60-90 cm of growth per year is a fairly conservative estimate.  In the eight years I grew it I cut it down to ground level once myself to keep it in bounds and had it cut down twice by harsh winters - the last time producing such a mess that I removed the remains.  I've now filled in the space with a red Ensete banana and an hydrangea.

Doing a bit of weeding in the garden yesterday I found a couple of seedlings of the euphorbiaNothing unusual in that - I often find seedlings of the various plants I grow.  Hardy geraniums, crocosmia, Freesia laxa, Libertia, Begonia grandis var evansiana, hellebores, even ferns - all pop up regularly amongst the rather more common garden weeds.  Some I pot up, others join the compost heap on the allotment (and, yes, if it likes you, even the treasured and desirable hardy begonia can become a weed).  OK, the euphorbia seedlings are a little unusual in being 20 feet / 6 metres from the site of the parent - entirely due to the exploding seed pods of the plant.  I remember a hot day in 2007 and the garden being peppered with the seeds as they were flung at fair velocity across the plot - probably the origin of the current seedlings.

But it all  leaves me with a problem.  I can, and will, pot up the seedlings.  I'd rather like to grow it in the garden again.  But I now simply don't have the room in the ground.  This plant takes up a lot of space - and doesn't wait around to do it.  So, if I want to keep it and enjoy that lovely honey scent, it will have to go permanently in a pot.  Which probably won't produce the best results.  Still, knowing my taste for tender plants I'm bound to have gaps if when we have more bad winters.  And maybe then it can go back in the ground to produce the next generation of seedlings.

Monday, August 15, 2011

Garden Bloggers Bloom Day August 2011

Another 15th of the month and another chance to illustrate what is flowering in my Plymouth garden.  As always, visiting May Dreams Garden blog will give you access to all the other gardens linking today.

As before, I'm including some of the more interesting plants and, while the photos have not all been taken today, the plants are all in flower today.  

Roscoea beesiana - another pretty little ginger for semi shade

Agapanthus 'Northern Star' - a robust deciduous type with large heads of dark blue flowers
Japanese anemone - Anemone x hybrida 'Honorine Jobert'

Crocosmia x crocosmiiflora - a bit weedy but good for bright colour in shade

Geranium 'Buxton's Blue' - a nice clump forming hardy geranium

Geranium wlassovianum - another good clump former

Lobelia 'Fan Scarlet' - short lived but very pretty perennials

Rosa 'Graham Thomas' - one of the English shrub roses

Tillandsia cyanea - in my little shade house
Clematis texensis 'Princess of Wales' - providing secondary colour on my winter jasmine
Trachelospermum jasminoides - beautifully scented evergreen climber growing by the rear garden gate

Begonia boliviensis 'Bonfire' - a summer visitor dying back to a tuber for overwintering
12 previously unillustrated plants for August.  A lot of the plants I've previously illustrated are still flowering - Passiflora edulis, Abutilon 'Patrick Synge', Freesia laxa, Iochroma grandiflora, Brugmansia, Hydrangeas and many others.  I wonder if I'll have 12 new ones to illustrate in September?

Tuesday, August 9, 2011

An August evening

Just been outside in preparation for locking up for the night.  It's dusk, the air still after the earlier breezes, reasonably warm but just beginning to dip below shirt sleeve levels of comfort.  There is a wonderful sweet scent hanging in the calm of the evening.  My one and only Brugmansia has opened a single trumpet flower and is wafting its perfume throughout the garden.

It's an apricot coloured form that I bought from Hill House nursery earlier this year.  50cm tall when I bought it, a planting hole filled with manure and regular liquid feeding has got it to nearly 2 metres tall.  It produced a couple of flowers earlier in the summer but is now gearing up to produce rather more.  The flowers are beautiful - but the scent is divine, an evening and night aroma designed to attract night flying pollinators.

Brugmansia 'Apricot'
From earlier experience an individual flower will last for about four days - but I've got others developing so I'll have some continuity.  With luck they'll scent the garden till October. 

Despite overwintering one outside a few years back most winters are too cold for the top growth to survive so I'll need to dig it up and, hopefully, overwinter it as a fairly dry skeleton in my shed before reviving it next spring.  It's worth the effort - the bigger the plant the greater the flowering display.  Though I may have to site it in a slightly better location.  My local snail population have wrecked havoc with the foliage - which rather destroys the effect of the big, softly textured leaves. 

No matter, the scent remains, encouraging me to linger outside as the light gradually fades and the garden becomes less and less visible.  Meanwhile, overhead, a single bat is patrolling.  It might, or might not enjoy the scent - but will enjoy the moths attracted to the blossom.

Sunday, August 7, 2011

Out of season flowering

OK, we've had a fairly miserable summer.  April was good, May and June generally cold, damp and disgusting, July a combination of a few nice days intermixed with a good many rotten ones.  August, so far, started all right but has now deteriorated.  In fact, it's windy and raining as I write.  But I didn't think it was bad enough to start winter flowering plants into bloom.

So I was a little surprised to see a little patch of yellow when looking out of the living room window this afternoon.  Dodging the showers, I went out to confirm that I was seeing what I thought I was seeing.  I was right.  Jasminium nudiflorum, the rather lax but easily trained as a wall shrub winter jasmine, was flowering.  Not just one flower but a whole branch was developing it's soft yellow tubular flowers.

Jasminium nudiflorum - taken during its more normal winter flowering
My plant is trained against an east wall and has never previously flowered before late November.  So why is it flowering now?  More to the point, is it likely to make a habit of this?  If so, it will disrupt my carefully planned (OK, accidentally thrown together) sequence of winter jasmine flowering in, would you believe, winter and Clematis texensis 'Princess of Wales' winding its way through the hanging stems for summer and early autumn interest.

I could, of course, put it down to the capriciousness of the Gods and sacrifice another burnt offering to propitiate them.  Another round of toast should do it.  Unfortunately, I was trained as a scientist so I tend to look for more rational explanations.  And my curiosity was piqued when I realised that in the front garden my reliably May - and only May - flowering Crinodendron hookerianum was also producing new buds and had already opened some of it's lovely red lantern flowers.  In August.

Crinodendron hookerianum
In temperate climates, with their distinct seasons, flowering is normally triggered by a combination of day length and/or temperature.  Here in Plymouth we had an early, unusually warm spring.  We've had very variable weather since then.  Flower buds that would normally be initiated as the day length shortens after mid summer but only slowly develop for flowering in winter - the jasmine - or late spring - the crinodendron - have been hastened into blooming out of season.  It shouldn't affect the normal flowering, there is plenty of time for things to settle back to normal.

Either that or we're all doomed.  Better warm up the toaster just in case.

Friday, August 5, 2011

Why is my 'Midnight Blue' Hydrangea red?

Hydrangea macrophylla 'Midnight Blue' - with red bracts

One of my earliest gardening memories is going on holiday to the English Lake District.  I was about 13 or 14 (so this was many, many years ago).  We went to Lake Windermere and there, on the shore, were masses of sky blue mophead macrophylla hydrangeas.  They looked absolutely fabulous to my untutored eye.  I knew they were hydrangeas.  We had them in my parent's and many other local gardens, in shades of white, pink or red.  But never blue.  It was fascinating.  Dad explained that we couldn't get them to flower in blue shades in Grimsby because of the soil, heavy clay mixed with chalk.  I knew enough about chemistry by this stage of my education to realise that he gardened on alkaline soil while the soil by Windermere's shore was acid.  A check in the school and town libraries confirmed that Hydrangea macrophylla was blue on acid soil, red or pink on alkaline soil.  I was used to using Litmus paper in class experiments so, it seemed pretty obvious that the pigments in the bracts that make up the colourful part of the mophead were, just like litmus paper, directly sensitive to the pH of the soil.

I probably went through the next 15 years thinking exactly that.  And then I started gardening for myself - and growing Hydrangeas.  Of course, as soon as you start to grow a plant you see it in all the local gardens.  I was on acid soil, the whole area was on acid soil, and the local hydrangeas were in every shade from brick red, through shades of pink into pale and deeper blue - even within the space of a few metres.  That's when you start questioning your earlier assumptions - and realise that it's a little more complicated than simple acidity or alkalinity of the soil.

Fortunately Hydrangea macrophylla - in both it's mophead and lacecap varieties - has long been a commercial florist's crop.  The colour change has long been known - and it's mechanism.  Without going into the biochemistry of the process (those days are long in my past) it is a reaction between aluminium salts and the anthocyanin pigment in the colourful parts of the flower head.  High aluminium gives a blue colour, low aluminium the more natural red.  Very acid soils - below pH 5.5 - allow aluminium salts to be freely available to the plant and hydrangeas are likely to be reliably blue.  Less acid to alkaline soils progressively lock up the aluminium salts.  Depending on the acidity of the soil and amount of aluminium natively present in the local soil the hydrangeas will respond in every colour from blue through to red.  Hence the variation even within a small area.

Where your soil is acid but the hydrangeas aren't colouring blue you can boost the availability of aluminium by watering with a diluted aluminium sulphate solution to boost the soil content.  This is available in garden centres.  Don't be tempted to exceed the recommended dose - aluminium sulphate is toxic to plants in higher concentrations.

Which still doesn't explain why my 'Midnight Blue' is red.  Well, I bought it (cheaply) in a distressed plants sale earlier this year.  I resuscitated it in it's pot before planting it out a month or so ago.  It must have been growing in alkaline or low aluminium content compost.  So, this year, the flowers are red.  Over the next couple of years they should change and I should, eventually, get a good blue.

Hydrangea macrophylla is not unique in this colour change - but it's not common.  The smaller Hydrangea serrata has the same properties and so does a rather rarer relative, Dichroa febrifuga.

Dichroa febrifuga
I grew this for a number of years in a large container but, alas, it succumbed to two bad winters. 

Just as an aside, I've seen many assertions that if you choose white mophead or lacecap hydrangeas you won't see the same colour changes.  In fact you do - just on a far smaller scale.  This is the centre of my repeat blooming white mophead 'Madame Emile Mouillere'.

Central flower of Hydrangea 'Madame Emile Mouillere'
A lovely blue.  Which bodes well for 'Midnight Blue'  when it eventually assumes its true colouring.

Tuesday, August 2, 2011


This is Pippa.

Pippa is a greyhound. 

Greyhounds are large dogs.

Pippa digs holes in the garden.

Greyhound sized holes.

Bad Pippa.

Normal blogging will be resumed once I've filled the latest attempt to dig to China.