Succession and Storms

It is now a week since the major storm Goretti whistled through Cornwall. We have been fairly lucky when compared to gardens and countryside west of St Austell where there has been significant loss of trees. it wasn’t as severe as either 1979 (when over 50 trees came down in the garden alone) or 1990 but it was quite a lively evening to be fair. Quite a number of the older deciduous trees in the park and surrounding shelter belts have come to grief.

In the image on the left below which was taken in November, there is a shadow outline of a copper beech tree, it’s behind the oak with a few leaves still hanging on. In the right hand image this same beech has taken a hit from the wind and broken up. Beech trees in this part of the world usually last somewhere between 150 - 200 years and this fella was nearing the end. It had recently dropped a major limb and there was ganoderma bracket fungus fruiting from the scar. Not a good sign so we planted a successor a couple of years ago as a replacement. Unfortunately Goretti took out the old one before the youngster had time to fill some of the space. We were too slow in getting the replacement planted.

Succession planting is tricky to get the right timing and we were at least 10 years too late here. But in the left hand image there is a lovely young Cork Oak (Quercus suber) which was planted after the 1990 storm and now starting to make an impact. There were 15 trees planted in the park every year for 10 years after 1990 which are now coming along nicely. The 1884 Tithe Map gave exact positions of mature trees and by the line drawing identifiable as a conifer or broadleaf. This was the template we used for those 150 trees and will continue to do so when another is failing or has failed!

Christmas Box or Sweet Box

Sarcococca wallichii is the most prominent of the species that is grown in the garden here and is an ideal plant to celebrate for Christmas 2025. Growing up to head height the starry white scented flowers are great for a whiff as the clump is right next to the path in a shady spot. It is quite the all rounder with glossy narrow leaves and shiny black fruit which start to develop while the plant is still flowering as can be seen here.

Native to medium elevations in The Central Himalaya it has been hardy outside here for over 20 years. The seed for this plant came from Nepal via Alan Jellyman who did so much to improve public parks in New Zealand especially in the Taranaki region. The winter display doesn’t last long if cut and brought inside while in flower but when the flowers are immature they will open inside and scent a whole room.

Happy Christmas one and all; it doesn’t look like any snow for us over the festive this year but with the weather pattern shifting to the east January looks as if it will initially be a bit colder at least…..

Quercus guyavifolia

I had noticed in previous years that the fruits from this oak dropped quite early in the season and I missed picking them off the tree before they had dropped and disappeared or were scoffed by rodents. This year I was ready early and picked a bag full while the acorns were still on the stem and put them in a dark cool room for a while till I got back to them.

Remembering today that I had this stash to sort out I tipped the bag out on the table to find that several had already started to push out roots from the acorn while still on the branchlets. These fruits were germinating in the cup after only a couple of weeks in a plastic bag, crazy stuff!. Watch this space as I will post a visual update on this acorns progress in another post.

After pausing for thought this impatience all makes sense. The Quercus group Heterobalanus has developed in cold, dry valleys of Eastern Asia where moisture isn’t available year round. Unlike the Cyclobalanopsis Group which is more suited to wetter areas of the same regions the Q. guyavifolia only has a limited season to fruit and germinate during the same summer monsoon period. Clever adaptation which has evolved with the regional geological uplift over millions of years.

The local goat herders in NW Yunnan from where this tree came from were keen to use the foliage for feeding their stock in the Autumn where it was piled up high along the side of the road in a side valley north of the Yangtze. Of all the oaks in this section, guyavifolia has the most striking foliage underside which is best viewed when planted with full exposure to the west where the late afternoon sun lights the tree up >> it’s a magnificent sight.

Metrosideros x subtomentosa Mistral

It has been a frustrating exercise attempting to grow the NZ Christmas Tree > Metrosideros excelsa > Pohutukawa, here in the garden. I have tried multiple times in many different places around all the well sheltered prime spots. As it is native only to the coastal regions of the upper half of the North Island where there is very little frost, if at all, this isn’t particularly surprising. There are many terrific huge old trees on Tresco in the Scilly Isles and in A Coruna in NW Spain (Two images below), where the tree grows to huge proportions in ideal European conditions.

Then along comes M x subtomentosa Mistral which is a natural hybrid involving M excelsa and M robusta. So i thought it would be worth a try to grow a Metrosideros with half excelsa genes at least! And it has worked… This image shows the small tree growing in the entrance to the garden where it has been happily growing for the past 20 years without suffering any damage from cold spells. The flowers are an even deeper red colour than in the picture and are showing off right now in mid summer, just like they do in NZ. It has monstered the pot that it was planted in and definitely isn’t afraid to use its aerial roots to find a new home in the flowerbed next door…

Metrosideros Mistral in Tregrehan Entrance

The pot has been eaten by Mistral.

The huge M excelsa in the A Coruna police station on Tui St

Aerial rooting display with symbolic Maori Koru in A Coruna

Rare Plant Fair 2025

On the countdown this week to another plant fair here at Tregrehan. There has been some welcome dribbly rain the last couple of days which has freshened up the garden no end. Most Bromeliad plants aren’t hardy in Cornwall but there are many Puya species which are especially if sited well with full sun and good drainage.

This Puya chilensis at the front gate has decided to open right on cue with a huge yellow spike emerging from the spiny shrub layer. This species isn’t monocarpic and I look forward to a larger clump in due course throwing up many of these flowering stems. Not quite sure why the lion on the sign has morphed into a funky mauve colour from its original grey but the colour combo with the Puya seems to work well.

We look forward to catching up with stallholders and visitors alike this Sunday. All info is posted on the website under the Events section.

Davidia involucrata

This old Davidia at Tregrehan must have been planted from amongst the very earliest in the country. The story of Wilson and Henry and the introduction into British horticulture, (but being pipped by the Frenchman Farges), of this unique plant is all part of plant hunting folklore now. The Tregrehan plant must have been planted in the first decade of the 20th Century but as there were none of the family living at Tregrehan at this time the planting date goes unrecorded. It was at one time a record tree for girth in the British Isles and was a widespreading tree often seen with the first plantings.

But as can be seen in the lower image several of the older stems have now collapsed leaving just one leaning off at a 45 degree angle. Next to this old stem at ground level there are many small basal shoots. These make good cuttings and several have been potted up and another one has been planted elsewhere in the garden. There is also a much larger vertical trunk now which I selected and left to grow on about 30 years ago. This part of the tree is taller than the original now and must be about 20 metres tall, and will become the tree in due course when the rest collapses. It is looking absolutely perfect this week and definitely worth a look if anyone is passing!

Original Davidia involucrata

Stems and root suckers of tree

Deutzia Study Day

There is a study day of the Genus Deutzia at White House Farm in Kent on Saturday the 24th May. These days at WHF run by Maurice Foster absolutely shouldn’t be missed if there is a chance of getting along. Maurice has been a big fan of these plants for decades and has an unrivalled collection which are ideal in a woodland or open setting. There are many complications within the group and it will be helpful for gardeners to hear Maurice’s views and hopefully this will also precipitate an update within Trees and Shrubs online.

At Tregrehan I have collected together a few of the more tender and evergreen species which do well in the Cornish climate such as the two shown below. D. crassifolia has a superb large truss with emerging young foliage a shade of lilac. Bob Cherry collected seed of this plant when travelling with botanists from the Kunming BG in the 1990’s. It was growing next to a waterfall in the Wuliang shan, Yunnan province, China, giving a clue as to its liking of a shady damp position in the garden. Slugs adore the young leaves and branchlets so protect when young.

Deutzia multiradiata is a cracking foliage plant with glossy leaves above and a silvery appearance on the underside. Worth growing for this feature alone it has clusters of terminal flowers in early summer. Two other evergreens that are performing well are D. pulchra from the Philippines collected by Crug Farm and D. taiwanensis from Howick.

Deutzia crassifolia

Deutzia multiradiata

Kahikatea

The Dacrycarpus dacrydioides is the tallest tree in the New Zealand forest growing to 60m plus. It is also more commonly called Kahikatea (Maori name), or White Pine (Timber name). Often seen in pure close grown stands in wetter swampy areas in both islands where the root system often forms raised and buttressed contortions to allow better aeration and stability. The large old fruiting specimen in the image below was lit up bright orange with this massive fruit loading in early April this year, easily seen from several hundred metres away. Where a group or isolated tree has been spared they make a very uplifting sight and its such a shame that so many of the largest were cleared for farming or for not very durable timber.

The lower image shows a small group of close grown trees at Tregrehan. I have tried to mimic conditions that they would be happy with in their natural situation. These trees are about 30 years old now and really starting to grow quickly when compared to other NZ Podocarpaceae. They are next to a stream and are happy in water for much of the winter where they have pushed on to 15m tall already. I think that a larger group is in order so i’ll aim to extend the gathering over the next few years.

Female fruiting Kahikatea at Waipatiki Beach NZ

Kahikatea at Deans Bush, note raised root system, Christchurch, NZ

Stand of Kahikatea at Tregrehan

Aucuba chinensis f. omeiensis

At Last….

The production of fruit on this stunning Aucuba has been a project in the making for a long time. The original plant came from Edward Needham and is the female in this image. Right next to it a number of years later I planted the collection from Roy Lancaster which is the male clone. Recently when we were picking up a large sweet chestnut that had fallen over right next to the Aucubas the crew noticed these red fruits. This is the first time we had seen this so hopefully as the small trees become mature there should be quite a winter display. As with most Aucuba they appreciate being planted as understory plants in quite deep shade, this keeps the foliage a good shade of green.

Both of these two collections came from Emei shan in West Sichuan many years ago when there was less regulation on seed introduction. They grow fairly low down on the mountain in wet evergreen forest but still seems reasonably hardy in UK cultivation away from freezing winds, and promise to grow into a small trees unlike many of the other dwarf species. The leathery foliage with a pale underside is attention grabbing in all seasons as can be seen here in the lower image of the male plant.

There is much debate concerning the taxonomy of this species and most scientists now place it under Aucuba chinensis along with other forms such as obcordata and angustifolia. I observed a plant recently that seemed to have several foliage forms on the same plant! This does indicate a quite unstable leaf and plant foliage so maybe A. chinensis is the best baseline species in fact and the other names are listed as forms of this, or as geographical varieties.

Mega Pleiosorbus Plants

The two species shown here have been rather an enigma for the past hundred years or so. The story is i’m afraid rather convoluted but begins with two collections made by Kingdon Ward KW 6743 and KW 7618 in the late 1920’s from Myanmar (Burma). They were named by Fischer from a Herb Sheet at RBG Kew as Eriobotrya wardii. These two collections resided under this name until more material was observed recently in SE Tibet, NE India and Myanmar. A much more recent expedition from the Kunming BG collected material in SE Tibet and was named Pleiosorbus megacarpa in 2000. Other generic names had been proposed in the meantime such as Sorbus, Pyrus, Micromeles and Raphiolepis until Keith Rushforth compared recent collections from Arunachal Pradesh and discovered key differences in the fruits between the collections. Please see Phytologia 100(4):233.2018 for more info if interested.

Both Pleiosorbus species have subsequently become established at Tregrehan and interestingly they are behaving in a completely different manner in the garden as can be seen in the two foliage images attached here. P. megacarpa showed lovely autumn tints until the leaves dropped in early December. In contrast the P. wardii started its growing season in December and had finished by Christmas, completely bonkers behaviour!! So far the soft growth on wardii has withstood light frosts. They both have proved devils to propagate from cuttings and so the propagation team from Westonbirt were brought in by Keith to see if we could succeed with air layering techniques. >>> Wound branch, sphagnum moss and hormone powder tightly ziplocked and left for two years. We will hopefully be successful when they are undone later this year.

Sorry about all the background info but their remote locations have meant little opportunity for scientific or horticultural study. They are potentially very attractive trees for the milder woodland gardens in the UK and elsewhere and are worth bringing attention to as they hopefully become more established in cultivation. Pleio (meaning more, plus or increase thereof) is a very apt use as part of the genus name as they are definitely Mega Pleio Sorbus. I can atest to being completely puzzled when first seen and Magnolia like as described by KW 99 years ago was a sound enough estimation from a distance!

Pleiosorbus wardii KR 11134 at Tregrehan in December

Fruit of Pleiosorbus megacarpa from Upper Siang, Arunachal Pradesh.

Original 1926 Kingdon Ward field note of Pleiosorbus wardii from Myanmar.

Wisdom and Wit

Tregrehan has lost one of its main supporters.

Sir Richard Carew Pole who has passed away recently was the longest serving member on our garden management committee, AND he never missed one meeting since being asked to join in 1990! With his unrivalled experience from the RHS and Royal Academy, as well as running his own Woodland Garden at Antony it has been a huge privilege for us that he found the time to help guide the development and garden opening here at Tregrehan. He understood the importance of sticking to the agenda at meetings and one knew that any point he did make was well backed by wisdom and thought. Humour was only just below the surface mind, and he loved to often lighten proceedings with a self deprecatory story or poke fun where he felt necessary.

Richard never doubted what we have been aiming to achieve and he has trusted us all the way over the past 35 years since the restoration and rejuvenation of the garden began in earnest. He loved Betula spp. and had a lovely collection in the old kitchen garden area at Antony. I took this image of a Betula utilis yesterday that was grown from seed collected in China. I post this photo at Christmas as a tribute to him and so that we can reflect on all of his help here and life of service, especially to Cornwall.

Richard would have liked this tree…..

Leafy Action

The recent Storm Darragh turned out to be quite a handful. Tracking right across the UK and Ireland in an unusual direction from the NW to SE with sustained northerly gales over a day or so there were the inevitable casualties in an old woodland garden. Luckily the collection survived fairly much intact with a bit of help from us to heave a couple of things back upright.

The Ginkgo was looking terrific, a perfect 100’ tower of yellow and then the next thing it had all of its coat knocked off in 24 hours. Quite a sight on the floor as can be seen in the attached image. The northerly also blew all the deciduous oak and lime leaves in the park down the hill against the fence at the bottom about 3 feet deep. As we are making nearly all our compost now this was a great result and meant we could shovel trailer loads into the leaf bin and also fill a few tonne bags as well, all good!

Neolitsea cuipala

I was looking at a few plants with a French friend today when we both were stopped in our tracks by this Neolitsea sp. We had wandered past on several prior occasions and admired the trinerved wonderfully glaucous foliage but this is the first time that it had produced any flowers, and they shone from a distance on a rather gloomy and misty morning.

This Neolitsea cuipala has been growing steadily here for the past 15 years or so and has made a shapely tree of about 8m or so. In fact there are two here planted either side of a path where the leaf action can be admired from underneath. Its home is the Upper Siang valley in Arunachal Pradesh, NE India where there is precipitation of some sort on virtually every day of the year. In the higher elevations of the evergreen forest at around 2500m this tree mixes with Rhodo spp. griffithianum and titapuriense, Pleiosorbus, other Lauraceae and a myriad of ferns and other epiphytes all dripping in the moss. Cornwall was doing its best to mimic these rather damp conditions today, it was a treat.

Sassafras mystery...

There are 3 species of the true Sassafras trees. The name has also been used confusingly in a vernacular sense referring to other Genera. Sassafras albidum is native to eastern North America where it forms suckering stands of medium sized trees.

But the two Eastern Asian spp are what this short Blog is concerned with. Sassafras tzumu from China has been grown in the UK for around 100 years but never become established or widely available. The second species Sassafras randaiense was introduced more recently by seed from the Taiwan Forestry Institute and is uncommon in its native habitat in Taiwan and appears on the red data list of trees at risk. Both species are represented at Tregrehan by fast growing trees up to 15m tall. There has never been any issue with damage from cold conditions but they are susceptible to branch break in heavy winds so shelter is ideal. The variably lobed foliage is extremely ornamental and colours in the spring and the autumn. The bark as illustrated here in the images is also attractive when young and also upon maturity. Small clusters of typically yellow Lauraceous flowers occur on naked branches prior to the foliage in late winter. I would definitely recommend planting either species if they become more available

Recently the garden was approached by an Institution in the USA who are going to run some genomic trials to help with fungal disease of other Lauraceae such as the avocado. There may be a chance of discovering some resistance in the Asian Sassafras and it would also be very interesting to discover whether there is a significant genetic difference between the two Asian spp. They are exceedingly difficult to tell apart from morphology and the species delineation as far as I can tell is largely based on Geography. The results will no doubt will be published in due course and we will be able to solve the mystery as to whether the Asian trees are really just one species after all….

Young bark of Sassafras tzumu

Mature bark and foliage of Sassafras randaiense

Foliage of S. tzumu starting to colour in October

Gingers...

I have been prompted to post an article on Gingers after the National Collection holder from Sussex visited the garden recently. Various Hedychium spp. are still performing well in the early autumn and I have chosen two to illustrate here. There hasn’t been much heat to speak of this summer but this orange/yellow H greenii below is looking great at the moment. It is one of the spp. that does appreciate the extra warmth from the west facing brickwork in the walled garden to flower well. It’s not much use in the shade of the woodland under all the trees.

The other image below is of a relatively new sp called Hedychium viridibracteatum from karst limestone in NE Vietnam. It has a distinctive spidery, white flower which gives off a lovely delicate fragrance. This is a welcome addition in the greenhouse flowering so late in the season. It was collected by Crug Farm from relatively low elevation so will stay inside until we can divide the clump and try outside in due course.

Champion Stick

Dr Owen Johnson has been updating the tree measurements in the garden over the past few days. He is recording data from all the potential champion trees for the Tree Register of the British Isles; TROBI. This involves taking height and girth measurements for 100’s of different specimens in the garden, from 2m in height to over 45m. The TROBI website is online and I encourage everyone to join this charity which allows access to the database of all trees of exceptional size in the UK. He is spending a couple of weeks in Cornwall updating many of the region’s tender and rarer trees.

While measuring this oak tree from Yunnan Province China on Monday in rather damp conditions, we suddenly realised that we had been photo bombed by a stick insect. There are no native sticks in the UK but in warmer sheltered areas of Cornwall there are populations which have built up over the past 100 years or so. There is a hedge in Par which is stacked full of New Zealand insects so the locals say. Their legs are very delicate and they should be left alone if encountered. This stick on the label was still hanging in there a few days after we first saw it…..

Rhododendron Time

The Rhodo time of the year is full on for the next week or so. Many of the scented Maddenia Section plants will be at their peak and with the bluebells, azaleas and some welcome sun the garden is looking great. This 1st image is a plant that was seed grown from NE Vietnam. Very early for this group which includes, liliiflorum, nuttallii and excellens it is a remarkable sight absolutely smothered in flowers. The 2nd image is of a hybrid, nuttallii x edgeworthii bred by my father Mike Hudson in NZ. Its very attractive keeping the bullate foliage of the Rh. edgeworthii and the large scented flowers of the Rh. nuttallii. There are many others dotted around in the woodland, many of which are perched on old rotting logs and stumps where they can emulate their natural position in their native habitat.

Save the Pot

Over the past couple of weeks we have been clearing out the prop house and potting things on. There are always a heap of pots where there hasn’t been any germination and moss and liverwort normally take over the surface making any germination of small seeds virtually impossible. Luckily most smaller seeds get away fairly quickly when sown so if nothing is showing the pot is ditched.

Other larger seeds we have to make a call as to how long its worthwhile keeping. With plants such as Melliodendron, Perkinsiodendron, and in this image Rehderodendron it can often take several years to break down the hard seed endocarp allowing moisture to penetrate and bring the embryo to life. This emerging seedling in the attached photo has finally emerged after 6 1/2 years which i think is the longest time yet. Breaking the dormancy on these woody kernels can be interesting. Rotary mower run over Davidia has been known to work as has putting Melliodendron into a vice until cracking also seems to speed the job up…..

The Sun

Suddenly the sun appeared in the midst of a very dreary Spring and with it these two plants lit up the corner of the walled garden. Sophora cassioides looks as if it should be from New Zealand but in fact it comes from Chile. Very similar once mature this Chilean species doesn’t have a juvenile phase unlike S. microphylla from NZ which is presumably due to a lack of giant flightless Moa birds to mow the foliage in South America. It flowers early in the season as can be seen here on a young plant.

Growing above this is a recently introduced form of Clematis armandii var hefengensis from China. This variety was given to me by Chris Sanders who wasn’t sure that it was hardy. I planted it on the walled garden under a large camellia which it has vigorously started to monster covering the bush in only a few years. It has proved perfectly hardy and is worth growing when compared to the type with its more numerous and larger petalled flower with lovely dark staining to the underside .

Christmas 2023

This image was taken a couple of weeks ago when we had a few centimetres of snow one morning. The Cathaya argyrophylla looked spectacular and very Christmas like for a few hours until the snow started to melt after lunch. In fact the predicted temperature for the 25th of December looks as if it will be in double figures Centigrade this year, so very mild for us here in Cornwall.

I first planted a couple of Cathaya trees here out in the woodland about 20 years ago and the roe deer bucks immediately knew a new, tasty, and critically endangered tree to completely wreck, which they proceeded to do. So after that initial debacle I planted the next two trees in and around the walled garden closer to the house. These trees have done well and are now around 4-5 metres tall with foliage to the ground, very ornamental plants even with no snow attached….

Merry Christmas everyone and the very best for 2024 from all of us at Tregrehan; we look forward to welcoming you again, (if you can make it), when the garden opens again in Mid March.