by Wally Richards

WHY DON’T MY PLANTS GROW?

I am often asked this question by gardeners who find that some or all their plants dont make much growth if any.

There are several possible reasons and a common one is NPK fertlisers locked up in the soil because of excessive use.

An example of this and is a man-made fertiliser that became very popular because of the TV Gardening show where the Prof would be tossing handfuls of Nitrophoska Blue over his gardens like it was confetti.

Now interestingly, (well I think it is interesting), I was the one that first introduced Nitrophoska Blue to home gardeners about 50 years ago. How it happened was that a rose society member in Palmerston North came to my garden centre and asked if I had Nitrophoska Blue. I didn’t but asked him what he wanted it for and was told that he had heard it was a good product to give to his roses. I told him that I would find out where it came from and get some in.

Nitrophoska was originally developed and introduced globally by the German chemical company BASF and Ravensdown became the NZ importer.

So I contacted Ravensdown and asked about obtaining a few kilos and their advice on how much should be applied to gardens and in particular roses. Their technical person said used sparingly for general purpose and about half a teaspoon per rose once a month would be ideal.

So I started selling Nitrophoska Blue in small 500 gram bags for $2 each with the instructions of using one half teaspoon per rose each month during growing season and 50 grams per square metre for general garden use.

It is a inexpensive (cheap) fertiliser that only costs about $2.00 a kilo in bulk. Commercial growers pay currently $1,830 for a metric tonne.

If applied as the Prof was doing on TV it locks up in the soil and plants get no benefit.

When people tell me that they have been using heavy quantities of fertilisers I tell then to drench the soil with Magic Botanic Liquid (MBL) at 20 ml per litre of water using a watering can. MBL unlocks the chemical fertilisers as well as the organic ones and plants then can have a feed and grow,

I have had some excellent reports from gardeners that have used the MBL in this manner one time only, the rest of the time as a 10 ml in a litre of water to spray the foliage of plants.

MBL we have found, sprayed onto plants that are sulking and not growing has kicked them into action soon after application.

Another product which has brought gardens to life is BioPhos sprinkled around gardens at 100 grams per square metre then lightly watered in and the plants take off. Likely they were lacking in phosphate.

Plants have evolved over millions of years and adapted to the conditions that they grow in; one of which is the pH of the growing medium or soil. Every plant has its preferred pH level and will thrive in that level which enables it to take up nutrients that are available. If the pH is outside of the tolerance which the plant needs, it cannot take up the nutrients that are available and grows poorly, no matter how much food you throw at it.

Some gardeners worry about the pH and buy inexpensive meters that are probes put into the soil to see what the pH is. Usually the reading they get on the metre is one of too high a acidity or far too low alkaline. This causes them to panic and hey want to know how to get the pH correct for the plants they are growing.

I ask them, ‘are plants and weeds growing ok or are they poorly?’ The normal reply is ‘everything is growing ok but my pH meter is reading such and such.’ I then explain to them that to obtain a true pH reading of the soil you need a pH meter that you calibrate with a Buffer solution to enable an accurate reading.

These meters range in price from $100 to over $500 and buffer solutions cost about $15 for each 250 ml solution.. a buffer solution of pH 4 for acid use and pH 10 for general use. With a known pH buffer solution you could use a cheap pH meter and once you see what the meter reads when putting into a known pH buffer, then you know how far out of kilter the meter is.

A better and less expensive way is to obtain a spa pool pH test kit or Litmus test kit for a few dollars. You take a small sample of soil from the area you wish to check and put it into a clean glass jar that has a lid. You fill the jar to half full with distilled pure water. It must be distilled pure H2O otherwise all other water may have its own pH reading.

With the lid on, you shake the contents for several minuets, then put your test strip into the dirty water and compare the reading to the colour chart supplied.

In a vegetable garden growing all crops other than tomatoes and potatoes you can get a good idea as to whether you need to make the soil more alkaline or not. To do this you plant two rows of peas about 50 cm long and 50 cm apart and with one row you sprinkle Wallys Calcium & Health along the row.

When they grow see if the row with the Calcium & Health appears better plants than the other row; if so then you need to apply the Calcium & Health to the garden.

If you find that the soil is too alkaline for the plants that need a more acidic growing medium then simply sprinkle Wallys Sulphur Powder over the soil to make it more acid.

Garden lime — they are not all equal in that if it is a hard lime/calcium it will take a long time to change the pH of the soil. A soft quick acting lime gives instant results.

The test is to wet thumb and forefinger and take a little of the lime powder and rub between the wet fingers. If gritty like sand it’s a hard lime, if it turns to a small slurry it is soft lime.

Plants like potatoes and tomatoes need calcium but not one that makes the soil alkaline.

For potatoes it’s best to use gypsum and for tomatoes dolomite.

Gypsum is calcium and sulphur, thus pH neutral and Dolomite is calcium and magnesium and also pH neutral.

Readers will realise that I am on and on about growing your own healthy food (boring but health critical) Now it has been revealed that NZ Health has admitted “nutrient depletion is caused by prescribed medications.”

Wow — you take medications prescribed for a health issue and they rob your body of nutrition and you are given no advice to offset this real problem for your overall health?

See for full story: https://envirowatchnz.com/2026/09/13/the-missing-system-what-health-nz-has-now-admitted-about-medication-induced-nutrient-depletion/

Get vital health from putting sulphur back into your food chain by simply adding some of Wallys Real Blood & Bone in the planting hole of your vegetables or incorporating into soil where you sow seeds.

Have the health back that we used to have in the 1950’s and 1960’s when Real Blood & Bone was used by market gardeners!

If you would like to watch or listen to our gardening session recorded recently by Rodney Hide and yours truly go to:

 https://rcr.media/episodes/gardening-with-wally-food-shortages-and-the-future-of-gardening

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