A Better Rainwater Harvesting Solution

I first heard about this solution about 10 years ago while trying to find a better solution to deal with the fact that we funnel all our rainwater off site one day, and then irrigate our gardens using municipal water the next day.

Arum lilies make great plants for rainwater gardens

If we are really forward thinking, we use green solutions such as water tanks, in which we try to catch as much water from our roofs as possible, store it, and then pump it out into our gardens. This really is a great solution. But I'd like to suggest an even better option.

Our soils were created to be natural water tanks. Depending on their composition, they (like sponges) have the ability to catch and hold water. They catch hundreds of thousands of litres of water, releasing it slowly over a period of time, either upward to the roots of plants, sideways into rivers, or downward into the groundwater below. Good soil is essentially a reservoir for plants to survive through periods of dryness. So why do we funnel it off into tanks, or even worse let it drain away into the stormwater system?

Normal rainwater could be funnelled into the soil where it belongs, and excess water overflows into the stormwater system.

The answer to this problem is actually an age old one, and it lies in using plants, and in shaping the soil to slow down and catch the water.

Instead of using the downpipes to carry water straight into our stormwater system or at least into tanks, the water would flow from the roof down the drainpipes and into a catchment area with plants that would naturally be found in wetlands. These plants can tolerate both waterlogged and dry conditions depending on the season. The water can then drain away naturally into the soil.

Vancouver's innovative stormwater solution

Another application is alongside large paved areas, like parking lots, driveways and roads. The water that comes off these areas usually has a mixture of oils, litter, and other pollutants that end up in our rivers and eventually the sea, creating huge long term problems. We should be creating filtration areas before the water runs into any kind of stormwater system.

This can be a beautiful way of bordering or softening hard areas like parking lots and roads, and in a water thirsty country like ours is an ideal way of conserving water in the place where it should be conserved.

Nothing is Certain, but Death of Plants, and Taxes

Taxes. A swear word in most people's vocabulary.

Nobody likes paying them, but we all enjoy the benefits of public libraries, smooth roads and waste removal.

I had an epiphany the other day - that having a beautiful garden requires the same investment as paying taxes. You only notice the problem, when its too late, and the infrastructure isn't there.

The insight came to me when I visited a garden recently, where I had been called in to consult (a few years ago), during the preparation stage of this garden.

At the time, my client was more concerned with the final product than with what went into getting it there (and trying to get there as economically as possible).

They rashly ignored my insistence that they pay more attention to the preparation of the soil. I suggested that they should almost spend a larger portion of their budget on remedial work for the soil, than on the plants. It fell on deaf ears - or perhaps I didn't articulate it well enough.

Either way, two years later, the result is a problem that is far more difficult to address. The plants are pale and sparse, and the grass is patchy and full of weeds.

My suggestion if you're still in the early stages - pay your garden taxes now. You'll reap the rewards later (literally). If your soil is in overdraft, its not too late to start making regular payments now.
Start by topdressing your lawn with a thin layer of good, rich compost, add copious amounts of compost to flower beds, and mulch wherever possible. It may take a while, but the fruit will be so much richer.

What does N:P:K stand for, and is it a four-letter word?

I'm asked this often, so here is the short answer:

N : Nitrogen (Good for growth of foliage)
P : Phosphorous (Good for roots and flowers)
K : Pottasium (Good for fruit & general health of the plant)
Four-letter word?: Yes & No

The numbers (e.g. 3:1:5 or 2:3:2) that you see on a bag of fertilizer represent the proportion of these 3 elements - N:P:K.

Some quick facts:

• A lack of Nitrogen is usually quite apparent when the green foliage of your lawn or plants becomes pale. (Although this is not the only reason for pale leaves)
• Phosphorous does not move through the soil, so it should only be added in small amounts near the roots of plants, so that it can be absorbed easily.
• Potassium deficiency shows up when the edges of leaves and the area between the veins start to go yellow. Potassium helps plants handle changes in temperature.
• Generally speaking, unless the fertiliser is slow release (it will have (SR) after the N:P:K) you should always water your plants straight after applying in order to prevent any burning of the plants, and to help them to absorb the nutrients easily. Wash your hands immediately for the same reason.
  
• The plant family Fabaceae (e.g. Peas, Beans, Acacia, Indigofera, Crotalaria) has a symbiotic relationship with bacteria which actually helps add Nitrogen to the soil naturally.
  

But good-old-fashioned granular or chemical fertilizer is poo-pooed (sorry I couldn't resist that) in many circles these days, rather there is a strong move towards using organic fertilizers instead.

The problem with this particular type of fertilizer has resulted from its over-use, and mis-use. Chemical fertilizers are sometimes applied in larger quantities than can be absorbed by the plants or held by the soil, they then leach down into the groundwater and rivers, and can result in the death of fish amongst other things.
It is also believed that in large quantities over time, they can actually poison the soil and kill off the natural organisms that are essential for plants and organisms in the soil.

My personal opinion is that chemical fertilizers should always be just a very small portion of the food that we provide for our soil and plants. Because the elements are in their basic form, and therefore easily absorbed, they are often great as a short term solution.
But organic fertilizers, such as composts and manures, provide a whole host of other macro and micro nutrients, as well as improving the structure of the soil. For these reasons, they are always better in the long run.

How do you improve clay soil?

This is a question I've been asked quite a bit lately, and it seems to be a common problem in many gardens. Put simply - clay soils have a very strong bond with water, and tend to get waterlogged, with very little space for oxygen for the roots to breath. The result being, that rot can set in very quickly, or at the least, plants tend to look unhappy and become diseased easily.

The simplest solution would be to 'soften' the soil by adding coarse sand (as much as is possible). The shape and size of coarse sand leaves lots of gaps for air, and makes the soil less 'sticky'.

Another way to fix clay soils, would be to add large amounts of compost or well-decomposed organic matter - this does the same thing as adding sand, but it will also improve the soil's fertility at the same time. The only problem is that you would need to add quite large quantities to see the equal 'softening' effect.

Also, bear in mind that clay soil compacts very easily when wet, and doesn't bounce back up the way sandy soil would. Because of this, make sure that when the soil is wet that you try to walk or run wheelbarrows over it as little as possible.

Beautiful Dirt, Beautiful Plants

Beautiful Dirt? It seems like a bit of an oxymoron, but, yes I think dirt is beautiful! Or at least it should be beautiful. Plants are just like humans, if you get their diet right, they will live long, healthy lives. They'll be less prone to disease, and will look good at the same time.

I've just given a soil sample report to a client, who's garden went through a bit of a rough patch around mid-winter. She called me in to look at the plants in a section of her garden that were looking a bit shabby, and in some cases were being attacked by aphids, scale and downey mildew.

Deciphering a soil analysis, is usually pretty daunting. The key is to know what you're looking for, and what all the figures mean.

The soil report for the 2 samples came back relatively positive, and this is what it looked like:

The report showed that a lack of Nitrogen (Cat2) would most likely be responsible for the poor health of the plants. The report shows that Phosphorous levels are very good, while Pottasium, Calcium, Magnesium, and Sodium levels are all healthy.

Clay content and organic matter is a little low.

Nitrogen is very low, and the pH is much too alkaline (most plants prefer a slightly acidic soil).

There is also the potential for deficiencies of micro-nutrients/elements such as Zinc and Copper, but this would be rectified by adding compost to the soil.

The overall best long-term solution would be to add regular large amounts of compost (as is usually the case) to all the beds, but particularly to the bank area below the house level. This will boost all the levels, but will increase the amount of organic matter in the soil, which in turn will help retain moisture and increase the plants abilities to absorb nutrients.

If chemical fertilizers (a short term solution) are used to boost nitrogen levels, then it is best to use Ammonium Sulphate Nitrogen (27%N) or ASN as this will help improve the pH slightly.

In general this specific report and remedial feeding of the soil could probably be easily applied to most of the Durban coastal surrounds.

The key to healthy plants is in the soil. If you can get the soil right, you take most of the irritating work out of the garden. Its also not something that you are ever finished with. Adding compost and feeding your soil should be a regular process, especially in areas like ours, with sandy soils and high rainfall. Most nutrients leach out of sandy soils very quickly.

But even clay soils can benefit from copious amounts of compost - it helps soften the soil, and reduces compaction. In short, you can never really add too much compost to the average garden to get beautiful dirt, and as a result - beautiful plants.