Seasonal Plants of Interest December 2013
Review of the year 2013
New Year’s Day 2013 was dry and the sun made an appearance; the mild weather that we ended 2012 with continued into January; 12.4°c just after midnight on the 3rd January. Later that morning bluebottles appeared.
The temperature for the first part of the month spiked along the double figure line, with the ice melting on the artificial rink in Princes Street Gardens.
RBGE was a localised climate we had very little snow when schools were shutting and transport was disrupted through the rest of the country in mid-January and indeed into March when Arran and the Ardnamurchan Peninsula had the worst snow storms for decades resulting in infrastructure damage and disruption. Logan Garden closed for three days due to the drifting snow.
The first cut of the lawns was made on 28th January, a task traditionally suited to the Easter weekend.
Snowdrops made a welcome appearance and were at their best for the dry sunny weekend of 16/17th February. Visitors appreciated these and the first of the Composites; Tussilago farfara; Coltsfoot.
A magnificent Snowdrop season with an area of high pressure stuck above us giving a fortnight of dry windless calm from late Feb into March.
A bitterly cold wind blew with dry powdery snow falling as an even cover over the city through the night of the 10th March.
Snow and a continual biting cold wind gave March a low average temperature. One of the advantages of this miserable weather was the extended Snowdrop season, lasting into the early days of April. Pans of Primula allionii also flowered remarkably well.
The average maximum temperature this March was 5.58°c. On one day only, Sunday 3rd did we reach double figures: 12.5°c.
Compare that to March 2012 when the average maximum was 12.7°c and we recorded only 6 days below10°c. The highest temperature recorded being 21.5°c on the 28th of the month. Again this year there was a dearth of Daffodils for the Easter weekend but for a different reason than last year.
Remember also the drought orders that were being implemented in various areas of England during spring 2012?
RBGE recorded 1.0mm of rain in March 2012. This year March yielded 16.2mm of rain and snow.
The temperature rise to double figures gave us a warm weekend in the middle of April. Buds expanded before our eyes. Then the cold front moved across again, cold desiccating winds and hail storms. The coldest most inhospitable spring I have known. Even the leaves on the Beech hedge left their appearance until 28th April, the latest date I have recorded.
Just as the statistics were released confirming this had been the coldest spring since 1979 the month of May warmed up. Woody plants had a spectacular year, flowering prolifically. Davidia involucrata was showered in white bracts. Near the John Hope Gateway a mass planting of Weigela hortensis was covered in pink blossom.
During the Midsummer fortnight warmth and the occasional heavy downpour gave herbaceous plantings the boost they required to fill the border. Conversely, there was even a time when the grass browned slightly, not a sight seen during the wet summer of 2012.
July arrived with temperatures into the 20°c; over the weekend of 6/7 July both days sat at 24°c.
The Delosperma lavisiae that Olive Hilliard and Bill Burtt collected in Africa flowered magnificently in appreciation of the unusual heat. In the demonstration garden the sun reflected from the orange petals of California Poppies, Eschscholzia californica was too bright to maintain the gaze.
By the middle of July south facing lawns were burnt brown with the heat and pressure from visitor numbers, a 17.7% increase on July 2012 counting 12,000 visitors in total.
The weather broke the week of 22nd July with thunder claps and rain falling like stair rods. This caused the Garden to return to lush growth from an arid appearance.
The warmth continued through August resulting in the haar from the River Forth enveloping the Garden in mist overnight towards the end of the month burning off as the sun’s heat burnt through. As the nights became cooler this damp atmosphere encouraged fungal bodies to sprout.
September brought news that this summer had been the warmest and driest since 2006; has it really been that long since we had a decent summer? It certainly made the mowing an easier task to manage, knowing the following day would be dry.
The warmth continued into the first week of September by when we were setting up hoses and sprinklers as many planted areas were showing signs of water stress.
Cooler wet weather came up from the south during the weekend of 6 - 8 September.
The grass minimum gave a reading of minus 0.37°c on the 8th of this month (September). During the September holiday weekend many visitors were sitting on the lawns, it was so dry, enjoying the early autumn ambience of the Garden. Then overnight the calm was shattered by the first storm of the season, gusting wind and much needed rain. The contrast illustrates how weather dependant we are for visitor footfall. Saturday 14th 3791 visitors dropped to 1418 on Sunday 15th the day of the storm.
The final weekend of the month saw in excess of 4500 visitors on each of the glorious autumnal days. It is the weather that keeps the Garden busy, or not.
After the poor harvest of conkers from Aesculus hippocastanum in 2012 it was good to see conkers falling from the trees as their spiked shells split. Hoards of children descend around the base of the trees looking for the bounty. It is heartening to know that computer games have not totally won the hearts and minds of the younger generation.
Autumn took its time arriving, on the 21st of October standing on the decking at the John Hope Gateway looking into the tree canopy of the Oak lawn it could have been late summer, so little colour change was visible. However with November came the white frosts and windscreen scraping. The Edinburgh city gritting lorries were out during the evening of 3rd November.
December and the first storm of the winter with wind gusting up to 52mph blowing through from the west followed by the briefest flurry of snow. This, on the 5th November when at 8.00am we were revelling in a temperature in excess of 10°C. By 1.30pm the temperature had dropped to 3°C and at this time the rain turned to snow. Then the mild weather returned through to the middle of December. This mild weather brought the heady scent from the Viburnum x bodnantense cultivars wafting through the air. Daisies sent out flowers and grass was mown as a result of the mild spell.
The attached images are of plants mentioned above that provided outstanding colour or interest during the year.
So far, this winter has been characterised by its mildness and the second part of December by its mucky end weather wise. Even with the turbulent weather I managed to cut a rose for the Christmas table from the garden at home. Both Christmas Day and Boxing Day recorded sunshine from 9.30am until 3.00pm. However the mild weather brings other perils. With just a little warmth from the bright sun, Rose stems were colonised with active greenfly. A timely reminder to maintain plant health and be aware of the spread of disease. There are now 115 sites in Scotland where Ash Dieback has been recorded.
The cold weather will arrive, just be prepared. Stay warm and observe the garden from the warmth of the John Hope Gateway or wander through the Glasshouse Experience.
Best wishes for the New Year and into 2014.
Highlight in red
Drawn to a stand of Cotoneaster growing on the mountainsides of Sichuan, China, by the crop of outstanding red berries; botanists collected seed and the resulting plants are now providing interest with superb early winter colour in the mass of small leaves held on the arching branch framework.
This season, in common with other members of the family Rosaceae, this Cotoneaster sp. nov. is bearing a noticeable crop of berries. Planted as a group and allowed to mature with minimal pruning this is a blocker that forms a quality visual barrier to corners and border edges.
All a quiver
The twin wing like bracts give momentum to the achene as they disperse from the parent plant in the wind.
A native to mixed forests of SW China where seed was collected in Yunnan Province at the altitudinal extremity of 2995m. The entry in the Flora of China gives an altitudinal range from 800 – 2400m.
Leaves holding for effect
Xanthorhiza simplicissima; a deciduous shrub with pinnate foliage that slowly colours into early winter. Surprisingly, a member of the Buttercup family, Ranunculaceae. Native to Eastern North America where it prefers damp woodland with soil that allows the suckering rootstock to increase.
This has a suckering habit and will rapidly move through the soil forming a woody shrubbery growing to 1.3m in height. At this time of year the foliage darkens through red to deep purple, almost black.
As observed during December 2012
Review of the year 2012
A very mild end to 2011, we recorded 12.5oC on the 31st December. On the 3rd January 2012 Edinburgh recorded wind speeds of over 100mph. The highest wind speeds for more than thirty years. A violent storm blew through from the early hours of the morning reducing 34 trees to matchwood and blowing out 600+ panes of glass from the glasshouse ranges. The storm and resulting damage led to closure to visitors for two days on the 3rd and 4th January.
The month continued with few frosts and became drier and settled. During early February when most of England and the north of Scotland were covered in snow Edinburgh basked in cold but clear sun filled days.
February continued dry and relatively mild. This gave us an ideal opportunity to progress the storm damage clear up and replanting.
Two downsides to the mild weather were the need to irrigate newly planted material through this period of low rainfall, but also the rapid growth of annual weed seedlings. At the end of February these were not noticeable; yet by the first week in March we appeared to have a green sheen covering bare, unmulched soil.
A dry warm spring; a record high temperature of 22.8oC was set for Scotland in March on Sunday March 25th; then 22.9oC on Monday 26th in Aboyne. Higher again on the 27th with Aboyne recording 23.6oC.
Everywhere is so dry, new plantings are desperate for regular irrigation, grass seed not germinating.
April and the temperature plummeted. It was a cold, dismal and continually wet month. The wettest April for 100 years according to weather records. To compound things, late frosts cut back emerging foliage and flower buds. A particularly extensive example of frost damage affected the Azalea lawn. Two cultivars, ‘Sunte Nectarine’ and ‘Frills’ caught the early morning sun causing the foliage to shrivel back.
When May arrived we thought an improvement in the climate would occur; how wrong we were. It was persistently miserable with light levels remaining low even with the lengthening days. The woody plants flowered reliably and the scents drifting on the air lifted spirits. It was not until the 22nd of May that temperatures again reached the low 20’s. Eight weeks is a long wait for sunshine and warmth, both for the plant collection and for those of us who maintain the Garden.
Mid-summer and we again experienced a long cool wet day. June continued to be wet and miserable. It was a dull month with sunshine hours reduced due to cloud cover. When the sun did break through there was intensity to it and lawns dried enabling mowing to progress. Our rainfall figures showed we had almost double the average for June.
Slugs and snails increased exponentially with the wet weather, in the evenings moving upwards from their shelter in the layer of thatch to the surface of the lawn.
Growth on hedges and extension growth on the majority of woody plants was phenomenal. Growth there may have been on Buddleja globosa yet this growth did not terminate in clusters of flowers.
Red Thread fungal infections were visible on the front lawns, a sure sign of a continual wet surface. Plantains grew bigger and Buttercups thrived in the lawns, there was a visible change in the vegetation mix where the lawns remained wet. We grew the largest Plantains I have ever seen. Admittedly these accidental seedlings were at the edge of a border bounded by a semi-permanent puddle. There was a poor set on fruit, including glasshouse tomatoes due to the lack of flight opportunities for pollinating insects with the cooler temperatures and continual rain. When these fruits did ripen they had a poor taste with none of the usual sweetness and to compound it, a heavy texture.
August ended with a frost overnight in Braemar. Then on September 3rd 25oC was recorded in Aberdeen, the highest September temperature recorded in the city.
At the Garden the first white grass frost occurred on 22nd September, recording -2.11oC; this a whole month earlier than in 2011. On Tuesday 25th we closed the Garden due to storm force winds and heavy rain, the previous day thunder and lightning had woken us early.
Whatever the weather the Hydrangea’s loved it; this season the mop heads were as large and as colourful as I have previously seen; lasting well into October.
Dismal news regarding conkers; the Scottish championship was cancelled in mid-October due to the lack of conkers. Certainly, the Aesculus hippocastanum on the north boundary of the Garden which always produces a crop was barren this year.
The early frosts and stormy weather conspired against plentiful autumn colour this year. The abscission layer was weakened by the early frosts and then canopies took a severe battering through stormy days and nights. Leaves fell to the ground without amassing the seasonal shades of autumn. Acer nikoense opposite the Palm House produced the best colour in the garden this season; vivid reds spread through the whole canopy.
Around the middle of November as a wave of mild weather swept in from the west we experienced a plague of midges. Working in the Garden around the 13/14th these drove us to distraction. In the east we are rarely troubled by these, certainly not so late in the season. A benefit of the mild weather was the heavy scent from the earliest flowers of Viburnum x bodnantense drifting on the air in the early mornings.
This has been a wet year, after predictions of a fine summer and drought the rain continued to fall. It resulted in the garden closing due to flooding, something we have not done before, but when all the access paths had areas that were under water in one area or another it was not sensible to open to visitors. As the weather got colder the rain turned to snow, the first fall dusting the Garden overnight on Sunday 2nd December. The cold weather was a feature of the first half of the month and then the second half, as we began 2012, turned mild, 11.6oC on the 31st. When have you known sweet peas in flower for Christmas before? I even have strawberries flowering and forming fruit in the garden at home.
Total rainfall for the year to 8.30am on the 31st December is 972.7mm. This compares to the long term Edinburgh average of 690mm, (remember those dry summers and the warmth of the 1970’s and 1980’s?) Previously the wettest year had been 2008 with a rainfall total of 896.9mm.
The images attached represent this year’s climatic conditions experienced at the Garden. Let us hope for a more benign climate in 2013. Best wishes for the New Year.
Sown on 17th April, under glass, by October the frosts will usually have browned the foliage, killing this annual. With the wet miserable summer did we notice a change as summer became autumn and now with the shortest day behind us it appears the Sweet Pea also is unaware of the change in season.
Best wishes for Christmas.
Walking through the Rhododendron collection in the Garden as dusk is falling, a rapid temperature drop and the stillness of the evening. Then a sound that resembles water as it flows, gently tinkling, along a shallow stream bed. Taken together these events give rise to a rare natural phenomenon occurring at the Garden. Below are the temperature and barometric pressure graphs for the afternoon of Tuesday 11th December. As can be seen there was a steep rise in temperature from below freezing at day break to the relative warmth at midday. Then a sudden drop, again to zero, by midnight on the 11th.
Walking through the Copse at 3.15pm on the 11th as the last of the songbirds were seeking shelter for the night I was aware of a constant noise rising from the mature Rhododendron oreodoxa shrubs. These plants have medium sized evergreen leaves of a relative sturdy nature.One of the features of evergreen Rhododendrons is the ability to reduce their leaf surface, thus reducing transpiration, in cold weather. Either by dropping horizontal rosettes of foliage to a more vertical position (see seasonal plants of interest 2nd February 2009; description of Rh. Lanigerum.) or by rolling the leaves to form a cylinder.
The source of the noise was the action of the leaves folding and then rolling to overlap forming perfect cylinders, of which the cigar rollers of Havana would be impressed. A constant, incessant chattering reminiscent of running water was amplified in the still air and by the amphitheatre effect of the planting. The noise is caused by ice crystals on the upper surface of the leaf scraping past the rigid surface of the underside of the leaf as the cylinder is formed.
Within the research collection is a young potted specimen of Rhododendron zoelleri, one of the Vireya collection. The large funnel shaped corolla is a bright mix of yellow to the base and orange shades to the outer reaches of the petals.
In open bloom the anthers are releasing cohesive strands of pollen, an evolutionary help in ensuring pollination of the stigma when flying insects move about pollinating within a mature stand of plants.
Saw teeth for winter fuel
Serratula seoanei bearing terminal light pink coloured composite flowers. The regular segmented flower bud structure is worth peering at before it expands revealing the anthers packed within. These late flowers fade and the seed appears as a pappus of bristles.
A related species S. tinctoria is commonly known as “Sawwort” due to the serrated leaf structure. The foliage on S. seoanei has shrivelled and discoloured but the feature remains visible.
As observed during December 2011
Review of the year 2011
Following the coldest and snowiest December (2010) on record, the respite from fresh snow over the New Year period lasted until 6.00pm on the evening of January 7th. Yes, at 7.30am on the 8th January, we were snowploughing the Garden’s roads again. Over the New Year the weather had been dry and the temperature a few degrees above freezing. With the snow melting there were signs of emerging Snowdrops. Frosty nights and crunchy snow underfoot then returned.
The Hamamelis were the main survivors sending out bloom as the lingering snow of the coldest winter, since the snowdrifts of winter 1962-3, melted. The paper thin petals contain minimum water compared to those of the Viburnum x bodnantense hybrids which were slaughtered by the devastating cold. So, as gardeners, we were pleased to see temperatures rising and appreciate the lengthening days as spring unfolded.
The lawns were slow into growth and just as the clocks were about to change and the longer evenings arrive a spell of dry settled weather commenced. This added to the slow recovery of the lawns. We eventually made the first cut on the 4th April, the latest date to commence mowing for the 24 years I have kept these records. In contrast, the Beech hedge leafed out from the 10th April, the earliest date I have recorded.
In the middle of April a mature specimen of Staphyllea pinnata flowered profusely. This was the first time this tree had flowered so noticeably, covered in pendulous racemes of creamy white blossom. This was just one, among many, of the tree species that flowered this year; outdoing previous year’s displays.
Easter became a pink season due to the amount of ornamental Cherry blossom; the traditional Easter Daffodil had flowered and faded.
Woody material continued to flower profusely into mid summer.
Early June saw gale force winds batter the tree collection. As the collection was in full leaf there was significant damage with limbs torn down and a couple of small trees uprooted.
The longest day again disappointed, rainfall and cloud cover. Not a sight of the sun. Just to keep it in perspective there was a frost on June 10th recording – 0.58C
The weekend commencing Friday July 8th saw torrential storms with thunder and lightening. Silt washed down and blocked drains and a lightening strike disabled the alarm panel controlling the fire alarms and climate controls for the glasshouses. Some areas of Edinburgh experienced flash floods with consequential damage. In total over the three days 43.6mm of rainfall was recorded falling in the Garden. That compares to 112.6mm throughout July 2010.
Summer was a wash out, cloud, torrential rain and when the sun made brief appearances it was of a burning intensity that sent those follicly challenged dashing for the sun cream. Home grown tomatoes did not have the sweetness of previous sun drenched years and spinach grew like rhubarb.
During August the lawns puddled and squelched as footsteps were placed on them. Mowing became a challenge due to the weight of the machines running over the lawns. Interestingly, seedlings of Plantago major ‘Rubrifolia’ appeared in the lawns. These easily spotted weeds have originated from the red leaved parent colony in the demonstration garden. They had not been noticed as a lawn weed at RBGE in seasons past. Here at the Garden we keep an eye on invasive species and an initiative to look through the Gardens database of living plants and reduce or de-access those plants which are deemed to be invasive is underway.
September arrived with early signs of autumn colour. There was sporadic flowering in many woody species, probably caused by the cold summer and low light levels. The plants confused into believing they had gone through winter and it was now spring and the season to send out flowering shoots. At the garden we were of the opinion we lived through a continual winter this year.
The last few days of September saw a period of warm sunny weather that was all too brief but most welcome. Visitor numbers peaked as the Edinburgh populace strolled through the green space.
It brought its own horticultural problems as the temperature in poly tunnels rose and humidity increased. The foliage of potatoes planted for a Christmas day lunch succumbed to fungal infection and mildew was found on salad leaves.
Ventilation, good air circulation and less water splash is the key to preventing these outbreaks.
The afternoon of 19th October became colder and on the morning of the 20th we had the first frost (-1.58oC ) whitening the lawns. This; coincidentally, is the same date as the first frost of 2010.
November continued mild; the Gardens’ weather station recorded the highest daily temperature in Scotland according to the Lothian’s area of the Met office, 17.2oC on Thursday 3rd November.
One of the downsides of the continuing mild weather are the midges. The team at Benmore were plagued into the tail end of the year. Highly unusual for the midge population to be active so late into the year.
Storm force wind heralded the start of December. The Garden closed twice due to the gales this month and a fall of snow melted overnight as we were reaching the shortest day. A benign end to the year, birds attempting the dawn chorus as we walk to work, cloud cover trapping the warmth, only a few days of frost and the incessant rain. One plant that is taking advantage of this mild weather is Euryops chrysanthemoides, this native South African is flowering with profusion in a sheltered corner of the back yard.
In conclusion, it has been a year that has shown extremes of weather stretching the limits of horticultural practices. One word of advice, the snowdrop and daffodil foliage is well advanced; take the opportunity to work through the borders now, any delay and your boots will crush these spring flowers.
Wrap up warmly and enjoy the New Year celebrations.
Best wishes for 2012.
’melis on the move
Preparing the site for the new alpine house involves taking stock of the existing plant collection and then embarking on ground clearance. Within the Hamamelis Border some plants were de-accessed but others merited a move.
The mature specimen of Hamamelis japonica var. arborea required considerable root ball preparation prior to cutting under with the extended planting bucket on the tractor front loader frame. Once on the plate of the bucket the hydraulics take the strain as Paul lifts it gently from the redevelopment area transferring it carefully across the road to the newly prepared site.
Here the protective hessian is removed from the root plate and it is back filled with top soil ameliorated with compost to give a good start. Keep an eye on it for flushing out in the spring.
For more information on the new Alpine House and Alpines CLICK HERE
To help fund the new Alpine House CLICK HERE
Best wishes for the Christmas season.
This dwarf specimen, protected within the north facing alpine frames, shares the genus with the large leaved specimens seen growing at the pond margins. Named after a Norwegian bishop, Ernst Gunnerus 1718 – 1773 although the plant itself is a native to New Zealand.
The stalkless globular fruit is held on upright red stalks protruding through the low dense mat of foliage. Almost translucent, they are an attractive golden gooseberry shade of yellow.
View from the roof
The John Hope Gateway visitor centre has a flat roof. To compensate for the developed footprint of the building a section has been planted as a green roof. The majority of the green carpet is composed of Sedum species and cultivars. After the harshness of last winter the biodiversity mix changed and it now appears the dominant plant is Sedum lydium.
There are a selection of weed species that have colonised the carpet. Many of these are annual weeds e.g. Senecio vulgaris, Poa annua, Sonchus asper. Due to the mild weather we are experiencing, these still show active growth and are continuing to flower and set seed. The leaves of Sonchus asper have spines that may cause a skin rash when weeding. The plant exudes a white milky sap when damaged.
At this elevated level the view takes the eye across the roofline and into the tree canopy. But this canopy occludes the distant city views to the south so the impression from the roof is one of seclusion.
There is a better view to the city from the south lawn of Inverleith House taking the eye over the New Town to the Pentland Hills. A good impression of impending weather as the hilltops show snow before it descends on the city.