Garden Myths: Number 4

You can get grass to grow well in the shade.

No you can’t. Grass will put up with a lot; how any plants will put up with being regularly cut down and walked all over? Like everything it has its limits and it is never happy in shade, needing full sun to do well. What about shade “tolerant” grass seed varieties you say? Yes, some grass is more tolerant of shade than others; but that’s not the same as happy in shade. If the shade is slight these are probably a good idea, but once you start to get under trees and the like you cannot expect them to be any better than any other grass.

Garden Myths: Number 3

Garden ponds need a filter.

Properly designed and planted a garden pond does not need a filter. Long ago when I was a child we had a garden pond, along with many other people of course, but no one had a filter on them. This was for a good reason; they didn’t exist for garden ponds. What changed things was when people in this country discovered the hobby of keeping Koi fish. These fish are large, colourful, expensive thugs that dig up any plants growing in the pond. This meant people wanted ponds with just the fish in them but the fish could not survive in these conditions so Koi keepers invented the pond filter. This allowed pond water to be artificially kept very clear so people quickly realised it was easier to fit one of these to the pond to get clear water without the fuss of making sure the pond was properly planted up.

Garden Myths: Number 2

Parsley seed must be soaked before you sow it.

Some plants seem to attract myth and superstition and parsley is one. The truth is parsley is slow to germinate and gardeners can be impatient, so people have looked to ways to speed things up. To this end it is often said you need to soak parsley seed to get it to germinate; however it will germinate without any soaking. What if any difference soaking makes how quickly it germinate I do not know, but have you ever tried to thinly sow wet seeds? You can’t, they just form a wet clump.

Personally, I just scatter the seed over a patch of fine earth and water it just as if were grass seed and wait. In a few weeks it starts to germinate and once the first true leaves appear you can easily spot what parsley and what isn’t so you can weed and thin as needed.

Garden Myths: Number 1

You must water Rhododendrons, Azaleas and Camellias with rainwater.

I’ve heard this many times in hard water areas, based no doubt on the fact hard water contains lime and lime is used to reduce the acidity of soils and composts. While it is true Rhododendrons and other ericaceous need acidic growing conditions the amount of lime in the hardest drinking water, such as my local one, is not going to be sufficient to effect the plant you are growing. Nurseries and garden centres large and small happily grow rhododendrons etc. and I have never come across one that didn’t use the ordinary tap water regardless of how hard or soft it is.

What is a species

The idea of a species is fundamental to gardening and botany, but what is a species? A dictionary will give you a definition but not one which allows you to say this group of plants forms a species, as opposed to say a subspecies. The Cambridge Illustrated Glossary of Botanical Terms describes a species as,

A group of closely related, mutually fertile individuals, showing constant differences from allied groups, the basic unit of classification


As it is this is a nice definition but does really tie down what a species actually is? No, the truth is a species is indefinable. I realise this is probably about as helpful as a fridge in an igloo but once you appreciate what a species actually is it makes complete sense.

So how did we end up in this situation? Well, if anyone is to blame its probably Charles Darwin and Alfred Russel Wallace. These two men independently came to the same conclusion, though they both arrived at it from observing the plants and animals on small islands.

Prior to this people saw species as distinct groups:


A figure illustrating 3 species
What is a species – figure 1


The problem with this was two fold. One where did the species come from originally and second where did the fossils come from people kept finding. The fossils were clearly very old: some similar to living things, while others where very different but still recognisable as plants or animals with characteristics at least similar to living examples.


A figure illustrating 3 species and 2 fossils.
What is a species – figure 2

By the 1850’s when Darwin first published his ideas on the origin of species the notion that living things appeared by evolution was widely accepted but the mechanism which made it work was unknown. What Darwin and Russel suggested was that species changed into new ones by a very gradual, survival driven, process of small changes. Each step in this evolution is so small as to be unnoticeable at the time and could only be appreciated with the benefit of hindsight. This process applied to all the species all of the time; but over many years and generations. The only reason we see separate species is because all of these intermediates have been lost, except for the very rare fossil.


A figure illustrating the evolutionary relationship between 3 species and 2 fossils.
What is a species – figure 3


If this is correct, and all the evidence we have found to date supports this, then there is no real starting point to a species and the only end point can be extinction. What we call a species is merely the extant remnants in a chain of gradual changes.

For this reason a species is rather like fog, you can see where it is, you can say you are in it or not, but it’s impossible to say exactly where it stops and starts. This is why no one has yet come up with a strict definition of what a species is, and in all likelihood they never will.


New Year – New Vegetable Plot

The arrival of the New Year inevitably starts you thinking about next summer’s vegetable crop and what to grow. This will of course be influenced by how much space you have available to grow food in and how keen a vegetable gardener you are. The vast majority of us only have so much space available, so compromises have as always have to be made.

For some people vegetable growing is a hobby; but for an increasing number of us it’s a way of using a bit of our garden to supplement our supply of food for the kitchen.  With this in mind, how are we going to gain the most benefit with the time and space available? The competing demands of work, children and family life are going to limit how much time we can realistically expect to spend on growing vegetables.

The next problem is where in the garden are you going to use and how much space can we spare. Everyone who uses the garden will have their own demands on the space available, growing flowers, playing football, sunbathing, eating out and so on. Whichever space is chosen it will have fit in with these competing demands and so its fair to say you are not going to be self sufficient in vegetables. So what are we going to chose to grow?

The first step must thinking what do we actually use in our cooking, lettuce may be easy to grow, but if no one in the house actually likes lettuce there is no point in wasting time growing it! The next step is what is practical, you may love asparagus but if you are going to move in a few years you will be gone by the time it starts cropping. Likewise if you are on stony, gravelly soil you are going to struggle to grow decent root crops such as carrots.

This should leave you with a list of possibilities. Now look down the list. What are you going to gain the most benefit from growing? In many cases just as good can be bought from the supermarket. Potatoes take a lot of space so are very unlikely to have the space to grow more than a fraction of your needs. If on the other hand you like green tomato chutney you are going to have to grow them yourself. Tomatoes are a good case in point, commercially grown tomatoes have the advantage that they are available all year round and they will only produce a small crop if grown outdoors in the UK, but the sad fact is the flavour of the varieties grown commercially is very poor.

By a process of elimination you will whittle your list down until you are left with what you can grow and will get some real benefit from. The collection you end up with may seem an eclectic mix, and in coming years you will adjust the range grown, but you should end up gaining some real value from a small corner of your garden.

Why do they keep changing plant names?

“That’s right!” shouted Vroomfondel, “we demand rigidly defined areas of doubt and uncertainty!”   

The Hitchhiker’s Guide to the Galaxy by Douglas Adams

The argument often made for using scientific plant names is that it provides consistency. If you ask for Alchemilla mollis that is what you’ll get. The problem is you keep finding different people referring to the same plant with different names. The exact opposite of what is wanted and causing confusion and irritation to many gardeners – what we want is clear stable names with no grey areas. Unfortunately “grey areas” are hard wired into the system of naming livings thing.

Wild scottish heather
Wild Scottish heather

The names of all living things, plants, animals, bacteria, politicians (possibly), etc are an attempt by mankind to order the world around us. To look at the state of things that may not seem to obvious a human obsessions but our history is littered with mans attempt to bring order and explanation to the world around him. To this end biologists try to group things in collections of related examples. This lead to plants and animals being divided into separate kingdoms and these were further divided and subdivided so like species were grouped into genera and like genera into families and so on. As this was going on it became clear that the range of species around us had changed over time, or evolved, and so it made sense to reflect these ancestral links in the arrangement of species, etc.

This hit two major stumbling blocks. The first and most obvious was the lack of

Sempervivum cultivar
Sempervivum cultivar

information about these ancestral forms. The vast, vast, VAST majority of species are extinct and lost forever. It needs a very unlikely set of circumstances for a plant or animal to be preserved as a fossil and even then the amount of detail preserved is still very limited. The other problem was how species evolve themselves. Initially it was believed that species were distinct with clear boundaries of some sort separating different species. Then came; Charles Darwin and Alfred Russel Wallace. Few people cannot have heard of Darwin but Wallace deserves his share of the credit for the theory of evolution Darwin explained in his book “The Origin of Species”. What the 50 year old Darwin wrote about was a bloody life and death struggle between all living things. This was the driving force behind the gradual change from one form into a new one. No longer were species entirely separate entities but a snap shot on their evolutionary journey.

So we find ourselves in a situation where it is impossible to have a clear definition of what a species is and nearly all the information we need to arrange the extant species in their places in the evolutionary map is lost for ever. I can best describe the situation thus: imagine you photograph everyone walking down you local high street one Saturday, lay all the pictures out and with only the pictures to go on try and work out not only who is related to who but how closely. I can guarantee you will disagree with who ever you are working with and have to frequently change your mind.

Now for the next question – why don’t we end up changing plant names more often?

Autumn Tidy Up

A leaf on a lawn covered by frost
A leaf on a lawn covered by frost

With the arrival of dark mornings thoughts turn to tidying the garden up for winter. The first frosts will soon finish off the annuals and tender perennials, while the hardy perennials die back for the winter and the deciduous trees and shrubs will take on their autumn colours before dropping their leaves.

Any tiding up will invariably create a collection of rubbish and gardening is no different. It’s often said “one man’s rubbish is another man’s treasure” so what treasure can we find before glibly throwing everything in a skip. Not everything is going to be re-usable; if you come upon what might be asbestos sheets, then only option is to contact your local authority for some specialist advice. That aside in most cases the limiting factor is your imagination.

Once you get rid of the bits of broken glass and rusty metal, which only the most artistic gardeners will be able to find a use for, you are left stones, rubble, lumps of wood, leaves, weeds and  other bits of greenery, and soil. As a rule its best to keep any topsoil you find surplus to you immediate needs. Small amounts of topsoil often come in handy for filling stump holes and the like but, due to its weight small quantities are hard to come by and expensive. Even if you have nowhere to store it, you can lose it by spreading on to the borders. If you think this is going to cause problems consider 50 kg of topsoil (the same weight as 2 bags of cement) will cover a patch 1.5 m by 1.5 m with a layer only 10 mm thick.

Shrubs in Autumn
Shrubs in Autumn


The green material will make good compost so long as care is taken when making it, and you have a little space for a compost heap/bin. Any woody material, like rose prunings, are best off shredded if they are to breakdown in a reasonable time. If you do not have the space, or time, our local authority will have a green waste composting service which will do the work for you and provide a quality controlled produce you can buy back from them when you need it.

It you have a lot of trees and shrubs you a likely to find, come autumn, you have a lot of dead leaves in the garden and these make an excellent soil improver in the form of leaf mould. Its worth considering that evergreen plants also shed lots of  leaves through the year, just take a walk through a conifer wood one day! Leaves tend to rot down more slowly that most of the green waste that goes into compost, so it’s often better to separate the leaves out. The leaves can be heaped up into a simple container made of course wire netting supported by posts or canes, just consider how you will get the leaf mould out again. As the leaves of different plants will rot down at different rates is best if the tougher leaves are shredded to help them brake down, and some people recommend adding some grass cutting to help the process along. The heap should not be allowed to dry and will need turning at least once. After a year you will have a very useful soil improver but ideally the heap should be left for two years.

Feed for health

As I have said before, the vast majority of domestic lawn problems come down to its feeding. That is not to say you can’t over feed a lawn, most people will have seen a lawn scorch where a heap of fertilizer has been left on it killing it. I also remember reading a report many years ago that some golf greens had been fed so heavily that the soil they were growing in could have legally been sold as fertilizer! So what to do? Clearly feed the lawn. Yes, I know it will make the lawn grow more and it will need cutting more – you will still only get round to cutting it at the weekend anyway.

If you read gardening books they will tell you about feeding a lawn in the spring and autumn, with more nitrogen in the spring to encourage lush growth and less nitrogen in the autumn to encourage less lush growth. There is though a problem with this, we know nitrogen is one of the most important plant nutrients but, there is always a ‘but’, nitrogen is not held in the soil and we don’t actually have any usable method of measuring the nitrogen that is in the soil. The latter we can nothing about the former we can. If the nitrogen is going to be leached out of the soil quite quickly, and the interaction between nitrogen and the remainder soil constituents is a very complex one, clearly the answer is to feed the lawn a little and often.

How often? About every 6 weeks during the growing season is probable about right. As to what to use, well a professional groundsman will use a specialist turf fertilizer but in practice: one you are not going to have access to these and two: unless you are looking after something like a golf course it will make no practical difference. In reality any general garden fertilizer will do the job, the fact the lawn is being feed and feed regularly is far more important. This way the grass is going to be well feed and able to outcompete weeds and diseases. Thus you will be well over half way to a good lawn capable of putting up with the use and abuse garden lawns live with. That is not to say it will not need occasional treatments but these should be the exception rather than the rule.

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.