pH

 

In simple terms this is how acid or alkaline something is – only a water based solution can have a pH. A pH of 7 is neutral, below 7 is acidic and above 7 is alkaline. The only way to know the pH of a soil is to measure it, either by adding it to a solution which changes colour according to the pH or using a pH meter. Both have there draw backs, with the solution it can be hard to check the colour as the soil discolours the liquid while on the other hand pH meters; if they are to be reliable they are expensive and need constant recalibration with a buffer solution. I’m very dubious about how reliable the ph meters for the domestic market are and I would say for your own garden the kits of indicator solutions are probably better.

 

Don’t get too hung up on the absolute accuracy of individual test as the pH of soil is vary variable and you may well find slightly different readings in different parts of your garden The advent of pH metes has lead to people publishing the recommended  for plants down to a tenth. I don’t really see this has any practical value.


Sequestered Iron

When plants are grown in a soil which is to alkaline for them they suffer from iron deficiency as a result of the effect the pH has on the nutrients which are available to plants growing in it. Sequestered iron is iron in a form which is not affected by the pH and so it remains available to the plants. It is really only a short term measure so it has to be regularly reapplied to the plants.

Making a seed/turf bed

Having selected a suitable machine and made sure you are familiar with how to operate it; the time has come to get our hands dirty. Before you go diving in stop a moment and take time to create a plan of action. Your soil should be moist, too wet and you will destroy the delicate structure of the soil and end up with a paddy field that’s dries to a hard crust which will block the roots of the newly geminated seeds, too dry and you will reduce the soil structure to dust which once it gets wet will for the same root blocking crust. That said most soils are quite forgiving but if anything err on the dry side; soils dry on the surface are very rarely so a centimetre down as the dry surface slows the drying of the soil below. You will also find cultivating soil combined with a gentle breeze will very effectively dry a soil that on the wet side. Try to avoid rain as the combination of churning the soil together with rain quickly makes a gooey mess. Perhaps not so obvious the problem of frost; a light frost shouldn’t cause a problem and the action of cultivating is putting energy into the soil anyway but a hard frost will stop things completely. I’ve seen heavy duty cultivators bounce on frozen soil many times!

That really bring us to one of the problems of rotary cultivators; if you look at the rotating tines you will see that the front edge of the tines travel down onto the soil so as to push the machine out of the soil. This reluctance to dig in to the soil makes getting them to penetrate the soil often difficult and in hard conditions they want to run along the surface. I remember once being told by a manager at a hire shop how he had been sent to collect a machine from a building site as the hirers had decided it was not suitable. On arriving he started looking around for the machine and found a fence panel with the outline of the machine punched through it. All that was missing was the outline of the operator running after it! This problem of running away is greatest the lighter in weight the machine, the tine driven ones being the worst by far but it can afflict all of this type of machine.

Levelling the ground

 

Its now time to start, try to work in a methodical fashion so that you cover all of the area but with the minimal of wasted time and effort. If you find the machine is struggling to break the soil up don’t try to fight it but just go over it a second or third time. Once finished you should have an area of loose fine soil which rakes over easily. Use a rake with solid metal tines and with it push the soil forward and backwards to level it out. The smoother you get the ground now; the smoother the lawn is going to be. As you go rake off any large stones, sticks or other rubbish and get rid of them.

Once satisfied with the surface it needs to be compacted either by rolling or your feet. DO NOT use a vibrating roller, or for that matter plate, this is soil not hardcore. You can hire rollers from the same hire shops as the cultivator and this is one of the only two times you need to roll a lawn. These rollers are generally filled with water to give them weight and after use emptied to make them easy to transport. For small areas your feet are best and this is done by what is called “toe and heel”. Put you weight on your heels and then shift it onto one heel. Shuffle the other foot forwards the length of your shoe and then shift your weight onto that heel. Now shuffle the other foot like wise. And repeat. You will look faintly ridiculous, but you will provide the neighbours with a little entertainment, and it is still the best way to prepare a lawn. Once you’ve gone over all the area it should be covered with footprints which you rake over (holding a rake as you go I find helps you keep you balance). If necessary you can repeat this if the surface is not sufficiently firm. If you walk on it you should see you footprints but you should not sink in.

Betula utilis var. jacquemontii

Betula utilis var. jacquemontii
Betula utilis var. jacquemontii

If you are looking for a tree for a small garden this selection of the Himalayan birch would be a good choice. B. jacquemontii differs from the B. utilis in its outstanding white bark. Never making a large tree the light foliage doesn’t cast troublesome dense shade.

Betula utilis var. jacquemontii bark

Betula utilis var. jacquemontii bark

The white peeling bark makes a striking feature either in a border or set amongst grass; particularly in groups. In either case the light shade it casts isn’t too restrictive on the range of plants that can grow underneath it. Its light canopy also makes it a good compromise when wanting to block the view of a neighbouring window without causing too much shade. Correctly named Betula utilis var. jacquemontii Spach as it was originally described by Édouard Spach (1801-1879)

A variety of Betula utilis hence the var. after the species name. A varieties is a range of plants which are more uniform than a species but not as narrow as a forma (or form). Betula utilis is found growing wild in the Himalayas and was given its scientific name by the Scottish botanist David Don in 1825 when he published a description of it. It was though not introduced to the west until 1849 by Sir Joseph Hooker.

Betula utilis var. jacquemontii foliage
Betula utilis var. jacquemontii foliage

Its peeling bark was traditionally used in the Himalayas to write on and in David Wheelers ‘Hortus Revisted: A Twenty-First Birthday Anthology’   Tony Shilling describes how among other things the bark is used to write on and is believed to have magical powers. The word utilis is botanical latin for useful or beneficial and the Latin word utilis gives us the word utility.

 

A more vigorous alternative would by Betula ermanii ‘Grayswood Hill’, it differs from B. jacquemontii by its pink tinged bark and very rough shoots.

Cultivating the ground

Ok, so we’ve decided to put the garden down to grass and decided if we are going to use seed or turf. Now it time to start. Get your weed killer out and CAREFULLY read the instructions. This will tell you if you need to dilute the chemical, by how much, what to use to spread it over the weeds, what safety precautions to take, how much to apply and when. Wait for a dry still day, you do not want the chemical washing off before its has had time to act or it blowing onto anywhere it causes unwanted damage, and get on wit it.

Now wait. Glyphosate weed killers take time to work; 10 to 14 days is perfectly normal. The first thing you may notice is the grasses start to turn faintly yellowy, but you have to look carefully. Shortly afterwards the weeds will all turn yellow and die; except for the green streaks where you missed. Now some of you will now be saying if you’ve carefully applied the weed killer you should have missed none of it. You’ve never done it. Trying to apply a more or less clear liquid over a garden without missing any patches is very difficult as you cannot clearly see where you’ve been and it is always best to err on the side of caution. Killing off bits of your neighbour’s lawn is likely to cause a degree of friction! Don’t worry, simply go out and treat any bits you’ve missed. You are probably asking why no bright spark has thought of a solution to this; well I’ve been down that road and every turning seems to lead to a dead end.

Once the weeds are well and truly dead, its time to prepare the ground. Start by clearing anything you can see on the surface such bits of rubble, scaffolding poles or anything else the builders saw fit to file away in the garden. You should now have a clear patch of soil with just the remains of some dead weeds. The next step is to cultivate the ground. Much is said in gardening books about digging, single digging, double digging, etc. Little of it covers the problem that is it is very hard work and very slow. I did once double dig a small area, as much as an experiment as any thing else and I don’t recommend it one bit. To be realistic you are going to have to use a machine. At this point you have to consider how big a machine can you get in the garden, its no good hiring a 600mm wide machine if it has to be taken through a 450 mm wide gate way, and how big a machine is it going to be practical to use in the space you’ve got.

You now have three options:

  • Buy a machine
  • Hire a machine
  • Get someone to do it for you

The problem with buying a machine is what you are going to do with it afterwards and a machine good enough for the job is going to be very expensive. Hiring a machine means you have to operate it yourself and you have to consider getting to and from the hire shop. Any good hire shop will provide you with good instructions on how to use the machine and for a charge will deliver and collect it but using one is still hard work and you have to consider is it for you. Finally you could pay someone to do it for you and I’m sure you will be able to find a selection of people in the local free papers able to provide the service but you have to accept the cost.

You may have noticed I haven’t mentioned what machine to use. In reality this is going to be a rotator cultivator, generally know as a Rotavator. Rotavator is in fact a trade name of the Howard Rotavator Company but has undergone the same transition as Hoover; where a trade name becomes so synonymous with a product it becomes a generic term for it. Rotory cultivates come in two basic flavours: tine driven and rear tined.

Tine driven rotary cultivator
Tine driven rotary cultivator
Rear tined rotary cultivator
Rear tined rotary cultivator

The tine driven ones have a set of rotating tines set under a motor and controlled by a pair of handles. The main problems with these are they tend to be rather light weight and are more prone to running away. This is where the tines rather than dig in run along the ground dragging the operator behind them. The rear tined machines have a pair of wheels under the motor and a set of rotating tines behind them; with the operator standing behind the tines holding the handles. These are heavier duty machines and less prone, though not immune, to running away. Being bigger and more complex machines they are both more expensive and heavier to move from site to site.

 

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.

Botanical Latin

Botanist quickly found Latin lacked words they needed to describe the parts of a plant, the Romans having never seen any need to do such things, so they modified the language for their own needs. The school Latin you may have learnt  has evolved considerably since the Romans; to the point a Roman would hardly recognise it. This has lead to Botanical Latin, which has branched off from ‘School Latin’, and has developed its own means for words and grammar. Anyone wanting to learn more would do well to look at Botanical Latin by William T. Stearns which is the standard text on the subject. Its very heavy going though!

To drain or not to drain that is the question.

When faced with an area of waterlogged garden the solution put forward is always to put a drain in, as if digging a trench and putting in a length of perforated pipe will magically make the problem go away. If only life was so easy. If you are going to drain a piece of ground you need to address two questions, one you may not be able to answer, the second your are going to have to.

The first question is what is coursing the poor drainage, this can have answers and sometimes the reason is never actually found. It is still important to try and understand the circumstances behind the problem if an effective means of tackling it is to be found. Possible courses are:

  • A buried layer stopping or slowing water percolating down to the water table
  • High water table
  • Springs
  • A depression blocking the natural drainage
  • A vertical structure blocking the natural drainage down a slope

The second is where you are going to drain the water to. This is the thing people always over look; they will happily stand looking at the problem debating the cause while never considering what they are going to do with the water once they have got it into a land drain. The bottom line is if you are going to drain an area you have to have somewhere to drain the water too. The problem is if the water isn’t draining away it may be because there is nowhere for it to drain to.

Before going any further down the drainage route the question needs to be asked; “is drainage the best solution?”

  • Drainage is expensive and a big upheaval
  • Persistently wet ground opens the opportunity to grow a range of different plants
  • Drainage isn’t always practical

What’s involved?

 

If you are going to drain an area of garden you have to consider the practicalities, you are going to have to dig a  trench – lots of trenches possibly –, bring in gravel and dispose of a lot of now unwanted subsoil. You also have to find somewhere to drain the unwanted water too, clean up all the mud (you are digging out very wet soil) and make good the area so that it once again looks like a garden and not the morning after the battle of the Somme!

Alternatively you could except the situation and fill the area with suitable plants. It is always far easier to plant with the prevailing conditions than try to fight them. Once you have accepted that this area is water logged and you are going to have to live with this it opens up whole new palette of plants to work with. Have a good look at the area and live with it for a while, at least a year, and seen how much sun it gets and when, is it wet all summer or just in winter, is there standing water in the area and how long for, all year, all winter or just when the weather is very wet. How big is the area affected and how does the area change over the course of the year. This way you can build up a mental map of the area so you appreciate which areas are going to be water logged just during winter, which all year round, which are going to be a bit wetter than ideal and which are going to be covered with standing water most of the year. These different areas provide you with the conditions needed to grow plants which would otherwise be very difficult otherwise. If you are prepared to spend a little time and patience you can turn what at first appeared a problem in to a real asset to you and your garden.

Finally not everywhere is going to be appropriate for this treatment and if the waterlogged area is your main area of garden then you are probably going to have to find a means of draining it; but for a small part of a garden, or even a large part of a very small garden, you may well be better seeing the possibilities of your garden and using them.

Soil

What soil is should at first sight be pretty self evident but to a soil scientist, yes there is such a person (they study soil), soil is a very complex thing. The problem is we all tend to overlook soil; it’s that muddy stuff in the garden. It is though a complex and delicate ecosystem in its own right. The main parts are:

  • Soil water
  • Organic mater
  • Soil flora
  • Soil fauna
  • Mineral components
  • Soil air