Author Archive | hortoris

Meterology for Gardeners

In theory Meterology should help our ability to predict weather conditions including snow, rains and floods based on seasonal cycles using observation, measurement and atmospheric conditions.

Red Sky at Night …………………

Old wives or gardeners tales and sayings such as rain before seven fine by eleven, wet on St Swithens day rain for 40 days, wet seaweed, cones opening in wet weather etc are based on observation and experience. However hightech is taking over with models used to predict the long term climate around the Earth.

Meteorological Equipment & Instruments

  • Gardeners rely on the thermometer for soil and air temperature. A max min thermometer will help measure/control night time temperatures.
  • Commercial growers will have sophisticated humidity meters to assist controlling growing conditions.
  • Anometers are used for measuring wind speed but I am happy enough with a simple wind vane in the garden.
  • There is now a plethora of digital weather stations for home and garden use

Flood Warning

Professional weather forecasts and warnings are important as they forewarn gardeners of potential problems. I usually react to them just too late not just in time.


Trees Near Buildings

The UK is experiencing a significant drought following a very wet spring. Trees were encouraged to put on extra foliage and they are now regretting the extra moisture they need to transpire. This is leading to more cracks in the surface soil and could lead to permanent damage.

Trees take up large volumes of water during summer. Shrinking and swelling of clay soils can be a concern but trees 30 feet from buildings should not be a major concern. However it is wise to avoid large vigorous and thirsty trees like Oak, Poplar and Willow.

Root Damage

  • Main roots are usually confined to the top 3 feet of soil
  • Shrubs and climbers are seldom implicated in root damage.
  • Swelling trunks close to buildings may squeeze against structures.
  • Root size and extent is variable dependant on species.They seldom penetrate well maintained drains but vulnerable drains should be repaired.
  • Roots radiate irregularly seeking moisture and nutrient. They may spread two to three times the height of the tree.

Subsidence & Structural Damage

  • Older buildings with shallow foundations are more vulnerable.
  • Soils other than shrinkable clay do not swell and contract as much as other soil and seldom cause damage.
  • The side of a building nearest the tree can settle due to its weight in dry soil causing cracked masonry, distorted doors and windows.
  • Fences, hedges and boundary walls may be damaged by proximity.
  • Paths can be lifted by robust roots.
  • Wind damage to trees may make them structurally unsafe.

General Tree Issues

  • A tree is the responsibility of the landowner who may be liable for any damage it causes.
  • Check with the local planning authority to establish if a tree has a ‘Tree Preservation Order’. They should also know if the garden is in a designated conservation order whose objective is to conserve landscape and public spaces in an area.
  • Trees have atendency to grow larger than you originally intended. They can block out light through your windows, shade gardens and over hang into your neighbors garden.
  • If you need to remove a large tree be aware that the large volume of water it previously transpired will remain in the ground and may lift the water table, swell the soil and cause ‘heave’ or displacement.
  • Gutters and roofs may suffer from leaf litter.
  • Surface roots and suckers can be invasive.

Further Tree Safety Tips

  • Think about the future life and nature of your tree before planting or starting work. It pays to plan ahead.
  • If a large tree needs pruning, lopping or taking down use a tree surgeon who has full insurance.
  • Consider neighbors and  overhangs across roads and public paths.



Dendrology for Gardeners

Dendrology is the the branch of botany and science about trees and other plants that have woody structures. It includes the natural history of trees, species identification, taxonomic classifications and economic significance.

Natural landscapes, forestry, arboreta, horticultural businesses and our gardens are locations that benefit from dendrological study. In the UK there are many parks and urban streets containing trees but the number seems to be diminishing. It is therefore up to gardeners to maintain an interest in growing and caring for trees and woody plants.

Book Cover

A new book to be published in 2019 ‘Dendrology: Cones, Flowers, Fruits and Seeds of Europe’ will provide a comprehensive overview of the morphology of reproductive organs of European woody plants in one resource. Over 355 species of trees and shrubs are to be described including species that originate from North America, Asia, South America, Australia and Africa. At a price of £200 this is not for your average gardener. Better to stick to your own note book costing less than a fiver (above from amazon).

Associated Facts

  • An arboretum is a botanical garden containing living collections of woody plants and is intended at least in part for scientific study. On the other hand a Xylarium is a herbarium containing a collection of wood specimens.
  • The aims of the International Dendrology Society are to promote the study and enjoyment of trees and other woody plants and to protect and conserve rare and endangered plant species worldwide.
  • Silviculture is the  science of controlling forests and woodlands and of forestry management.
  • Dendrochronology is the art and science of tree-rings. Dendroclimatology uses tree-rings and wood density to analyse the that climate was likely to have caused the rings.

Transpiration for Gardeners

Transpiration is a basic and crucial function that moves water around plants to cool and keep them healthy. Leaves have pores or stomata that open to allow moisture to transpire or evaporate. Large trees can transpire up to 500 gallons per day, our garden plants transpire far less but enough to cause wilting if there is insufficient moisture for the plant. Stems and flowers can also transpire and loose water.

Transpiration Strategies

  • Many trees have wide spreading and deep roots to provide the moisture they need.
  • Tomato plants have a deep main root to gather water and surface roots for feeding. Leaves can also wither or be defoliated to reduce water loss.
  • Succulents save water by opening the stomata pores at night to reduce transpiration and often have  waxy leaves. Cacti don’t have leaves and few stomata elsewhere so transpire very little.
  • Many plants loose there turgidity when short of water and thus transpiration is reduced.
  • Other  plants have small leaves or hairy leaves
  • Mediterranean natives may have silvery reflective leaves, or produce volatile  oils to reduce transpiration by reduced evaporation.


Plants & Gardeners Water Strategies

  • Many plant leaves are designed by nature to funnel water to suit the plants needs. Check how Rhubarb leaves collect water over a large surface but it is channeled to the ridges that take it to the roots. You may have heard the saying ‘ water rhubarb even when it is raining’.
  • Soft leaves seem to loose more moisture and the more leaves then the more they transpire. Hence gardeners need to mulch and water plants during dry spells to sustain transpiration.
  • Plants in pots still transpire and water hungry plants may not be suitable for containers for that reason. Remember the bigger the pot the more soil and thus moisture it could contain.
  • Shade and wind breaks can reduce water loss by cutting down on transpiration. You can have too much of a good thing and wind and sun are an enemy to successful transpiration.
  • Evergreens transpire even in winter but our climate is generally able to provide the water needed but be wary of long hard frosts particularly for young plants.

Kale leaves are shaped to harvest rain.

Brugsmania build in a water trap

Pink Rose Dew by name and nature








Gardening Robots

Where would we be if there weren’t already numerous robots used in the gardening industry. Do you imagine there are thousands of Dutch gardeners pricking out the seedlings of the soon to be gaudy annuals on supermarket displays or thousands of Chinese coolies picking individual seeds for our packeted seed industry (well may be in this case).

Glasshouses have many automated facilities from sowing, watering and potting and these are becoming economic for some gardeners. Soon we will be able to do all our gardening from this position.

What of other robots to help individual gardeners in their own gardens perhaps for weeding? Early gardeners would be fascinated with the electronic tools now available not least the automatic programmed lawn mowers.

Robot Gardeners Questions

  • I wonder how robots will be propagated
  • What task would your first robot be programmed to do?
  • Farmers are gaining a new range of precision implements for spraying and crop management. Will the cost saving be passed on to consumers.
  • Will garden centers become full of robots instead of gifts and bric-a-brac

Fruit picked by human robot!

I will not be allowing robots to take on my favorite task of drinking a gin and tonic at he end of a session in the garden.


A Trio of Purple Leaves

It is hard to ignore plants with leaves as stunning as these in a Parks garden. The purple is from one of the Sumachs or Rhus family. Selecting plants that contrast in colour shape or form is part of the skill of gardening but starting with plants like these is a good beginning.

Purple is one of my favourite leaf colours of the moment and the Lamium below is called Perilla fructenscens. I am putting several plants in one area of my garden and will see how well they get on with one another.

This Heuchera surprised me growing in a wall cleft with thin soil. I do not remember planting it in what I thought would be a hostile location.


Purple Patch in Your Garden

As gardeners mature they enter a purple patch in their life and potentially in the garden. Some of the best plants with purple or coppery coloured leaves take several years to mature like the notional gardener. Amongst the favourites must be the copper beech and the many Acers with reddish leaves.

Photographed against a blue sky the colour glows out in the morning sunshine. Unphotographed this purple patch gardener is probably very content for it to be so.

Acer palmatum have fine leaves that are not very dense and allow light and breeze to pass through. If it is a wind rather than a zephyr the leaves can suffer from wind burn. Many purple gardeners have got that way from wind and sun burn



I was struck by the two pictures of plants flowering virtually two seasons apart but similar in colour and floral form. The spring Primula has a purple outer petal getting redder by the centre until it becomes yellow. The late summer flowering Redskin Dahlia has a similar pattern to the petals with the yellow stamen having a similar kaleidoscope effect.

The leaf textures and colours are quite different but like the purple flowers they will also repay close attention. Colour in the garden needs close observation and sometimes a bit of serendipity. This will be helped by a passing understanding of light and reflections within the colour spectrum. For more information see Garden Colour Tips

Gardeners Tips 2011 acer

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Tree Peonies from the Far East

tree peony

History of Tree Peonies

The ancient Chinese have cultivated Tree Peonies for over 1500 years. Prized specimens are and were grown for medicinal purposes as they contain glucocides and alkolides. The  imperial palace gardens had many specimens that became quite valuable.

The tree peony was, for a time, the national flower of China and it is thought Chairman Mao sought to ban their growth as a decadent pastime. The root of P suffruicosa has been used in medicine for centuries.

Plants were transported to Japan in the 14th century. The Japanese  bred tree peonies creating over 1200 hybrids some of which are still grown today.

The cult status of Japanese Tree peonies encouraged 18th century plant hunters to import tree peonies in to Europe, particularly France and England. These plant hunters like Veitch, Joseph Rock and Kelway started their own breeding programmes from some of the five wild species and other hybrids.



The Americans crossed P.lutea (above) and P. delavayi with Japanese hybrids to produce some of the vibrant colours now available. The flowers have a short but colourful life! The shrubs are far more long lived.

Tree peonies have long featured in oriental watercolour paintings. by Zou Yigui (1686–1772). Some of the varieties, like ‘Yao’s Yellow’ and ‘Wei’s Purple’ are  depicted in a series of paintings  mentioned in the Record of the Tree Peonies of Luoyang  Ouyang xiu (1007-1072 CE).


Imagine the splendid sight when all the buds open.




A Garden by any Other Name

Naming of Garden Areas

Previously I have stuck to traditional names for bits of my garden. Veg plot, rockery, orchard (when I feel posh), rose bed, border, hedge and similar names have delineate what and where I was trying to grow.

Then I  launched some new names including the Den Den for a mixture of lolly pop like Primula denticulata .  This naming obsession started some years ago with the ‘Stumpery’ when I couldn’t dig out and dispose of the whole of a conifer root.

‘Alpine Land’ speaks for itself and reflects the time I was a keen member of the AGS. I collected lots of rocks and build slopes and appropriate habitats. Perhaps it deserves a better name.

The Pinkery has many dianthus and Japan Land has more statues and hard landscape and deserves more space.

My favourite bed is Rhodo Road which will come into its own as spring develops. There are currently 3 early white bloomers that have eluded the frost.

Mole Mound contains some plastic moles or heads thereof, a big pile of dumped top soil which turned out to be subsoil and some shrubs.

The whole plot is named Fairfaxery Gardens after the street where it edges the roadside. I do not grow any more successfully but ……..they say give a dog a bad name but the garden may not be perfect but it isn’t a dog.


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