This is classification of plants below the level of species which share common characteristics but would freely interbreed with other varieties of the same species if the opportunity arose. For this reason different varieties are often separated geographically. When writing the name of a plant the variety name is written in italics or underlined, is immediately preceded by var. in normal type and this follows the species name. There tends to be a lot of confusion between variety and cultivar but the former only relates to plants which originate in the wild and the latter to plants which originate in cultivation.


This is a plant which has been selected in cultivation because of specific characteristics it shows which separate it from its wild origins and other cultivars. The rules regarding what is a cultivar, how it is named and how the word is used are laid down in the International Code of Nomenclature for Cultivated Plants. Only plants which are not found in the wild can be called cultivars and to show that they are the cultivar name is written in normal upright letters and enclosed in single quotation marks.

Acer palmatum var. dissectum

Acer palmatum var. dissectum
Acer palmatum var. dissectum

Acer palmatum var. dissectumis a much used garden plant where something striking but delicate is wanted. Much loved in “Japanese” style gardens where it mixes well with gravel and boulders, a position which allows it to be ground in isolation so as to show off its dome of draping branches.  They are slow growing bushes slowly forming a small shrub after many years.

Acer palmatum var. dissectum foliage
Acer palmatum var. dissectum foliage

Not fussy plants they will grow in most decent garden soil though they do best in moist but free draining soils. The finely divided, thin leaves are prone to damage by wind and sun so they are best in a sheltered part of the garden with light shade, but not heavy or dry shade.

Known as the Cut Leaf Japanese Maple due to A. palmatum being known as the Japanese Maple as it comes from Japan, central China and Korea and its leaves being finely divided. The naming of Acer dissectum is confused, a situation caused at least in part by confusion between botanical names and those of cultivated plants. It is often named as Acer palmatum ‘Dissectum’ but that would only be if the plant did not exist naturally in the wild, as that form of name is only used for a cultivar. Things are further complicated by the many cultivars of Acer palmatum var. dissectum which have been raised and are available, Acer palmatum var. dissectum‘Garnet’ being a particularly nice example with red tinged foliage (this being an example of a cultivar of a variety).

Acer palmatum var. dissectum 'Garnet'
Acer palmatum var. dissectum ‘Garnet’
Acer palmatum var. dissectum 'Garnett' foliage
Acer palmatum var. dissectum ‘Garnett’ foliage

Is lime poisonous to Rhododendrons?

The pH confusion

People get terribly worried about lime near Rhododendrons, to the extent that some people insist that you should never water ericaceous plants with hard water. The problem is the whole soil pH thing courses all sorts of confusion. So let’s ignore all that’s been said before and start from the very beginning.  First off soil contains water but of course its not pure water it contains allsorts of dissolved minerals the plants need to grow. These are called plant nutrients and their presence is not enough; they must be in a form which makes them available for the plants to take up. The soil water will also have a pH; all water based solutions have one. How it is calculated isn’t important for our purposes but it effect is.

The sugar analogy

For a minute let us imagine we are dissolving sugar in water, we can carry on adding more and more sugar until no mater how long we stir the water no more sugar will dissolve. Now imagine we start to heat the sugar and water gently on a stove, the sugar will all now dissolve and we can dissolve still more. Now imagine the temperature of the water is the pH and the sugar is one of the plant nutrients. As the pH is altered the amount of the nutrient that is available in the soil water also changes. To further complicate things, as if it was needed, the availability of different nutrients changes differently as the pH changes.

The result of all this is that in alkaline conditions there is a lot less Iron, Manganese, Zinc, Copper and cobalt available for plants to take up than there is in acidic soil conditions. Just adding these nutrients to the soil is not going to help as the same process that had made them unavailable in the first place is going to act on the additional nutrients making them unavailable; if a pint pot is full pouring more water in it still leaves a pint of water.

Manipulating the pH

This leaves two options: change the pH or provide the missing nutrients some other way. Changing the pH of a soil is not that easy as the complex system that makes up soils tends to resist the change moving the pH back to the original level when to try to change it. Moving a soil towards an alkaline pH is the easier than towards an acid pH one.  One is to add an acidic compost to the soil but the only readily available one is peat and that is becoming increasingly problematic because of the environmental concerns surrounding it. A second means of making the soil more acidic is to add a chemical to it. Three chemicals are generally recommended: sulphur, aluminium sulphate and ferrous sulphate. The other option is to provide an alternative source of the missing nutrients for the plants and this can be achieved by using sequestered iron which provides the missing iron in a form that remains available even if the pH would make it unavailable.

After all of this you may have noticed lime has not been mentioned since the first sentence. Lime is in practice mainly calcium carbonate with some other chemicals mixed in according to the source. The calcium is a plant nutrient but its carbonate has the effect of make the soil water more alkaline and it is this change to the soil water, not the lime, which has the effect on the ericaceous plants.

Soft Landscaping

This loose term is more frequently seen used within professional horticulture but simply means the soft things that grow ( i.e. plants) and the soil or compost they grow in. So it includes trees, shrubs, hardy perennials, grass, etc.. It generally doesn’t include vegetables grown purely for consumption, there are a number of very ornamental vegetable that would then be soft landscaping, as commercially a landscaper would not normally be involved in vegetable growing, just providing space for their cultivation in a garden. Commercially vegetable growing would be something undertaken by a market gardener which has nothing to do with landscaping.

Nutcutts Book of Plants

It may seem strange to include in this list what is to a large part a nursery catalogue, and it is unashamedly in a part an advertisement for Nutcutts. The thing is it is a treasure trove of information on garden plants presented in a concise and assessable style. Thought the content is about the 3000 plants they grow; that range is sufficient to cover most plants you will encounter in the average garden and the plants included come with wealth of pertinent information regarding a plants size, features and where to plant it.

Divided into 5 sections, of which the second and fourth are the most valuable. The first deals briefly with Nutcutts history and present services but the second section provides a vast wealth of information set out as short detailed notes on a vast range of plants grouped under trees, shrubs, climbers, etc. The third section extends this range by treat a range of that plants they sell but do not produce themselves in the same way.

The fourth section though provides a collection of lists. Each list provides a range of plants suited to specific locations and/or uses. These lists can be cross referenced with one another and the descriptions in section two and three to provide a very powerful tool for gardeners to build up a list of possible plants for a specific location and/or use in the garden. Equally they will though up suggestions that you have not heard of or that had simply slipped your mind.

The final short section provides a range of tips and advice on the establishment and care of plants.

As it is a small book the depth of information and the range of plants covered is very limited, but it still covers most of the plants found in gardens and garden centres, or at least a close example, making it invaluable when first point of reference when trying to decide what to do with a particular plant or part of a garden.


A plant, larger than a shrub, with a one or occasionally 2 or more clear stems which form a trunk(s). Above the trunk is a system of branches which gradually increase over the years.


A plant with a system of woody stems which branch out and last from one year to the next gradually increasing in size. Ranges from prostate to several metres in height.

Photinia ‘Red Robin’

Photinia 'Red Robin'
Photinia ‘Red Robin’

This is a very common shrub in gardens – that is not to say it isn’t very worth while one to have in your garden. It has a lot of desirable features to recommend it. It will happily grow in most gardens being happy in sandy or clay soils. Its large evergreen foliage makes it a good screening plant and in a few of years it will reach 2 metres in height.

It’s easily identified by its red shoots, the leaves emerge strong red colour which persists at the leaves grow, only gradually fading to a glossy green as they mature.

Photinia-'Red-Robin' shoot
Photinia-‘Red-Robin’ shoot

Its’ dense foliage as well as making it a good plant for hedges and screening also make it very effective at smoothing out weed underneath it. In a border you should allow about 1.2 metres by 1.2 metres for it. As a hedge, either formal or informal a single row spaced 600 mm to 900 mm apart will have a good screen. The exact spacing being decided on by the size of the plants you are starting with, the cost and how long you are prepared to wait for them to close up to form a continuous hedge.

Photinia-'Red-Robin' hedge
Photinia-‘Red-Robin’ hedge

Photinia x fraseri ‘Red Robin’ as it is more correctly known is a selection from the hybrid between two plants P.glabra and P. serratifolia. Though P. ‘Red Robin’ was introduced to this country from New Zealand its parents, along with the rest of the genus come from the Himalayas. Its’ distinctive foliage make it hard to confuse with other plants, visually the most likely is Pieris ‘Forest Flame’ which also has striking red shoots but this is an altogether smaller plant and it regularly flowers in the UK which Photinia ‘Red Robin’ does not. The genus Photinia is in the very large and horticulturally important rose family.

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