Potting mixes are not all the same!

Commercial Potting Mix Makers

Potting mixes are not all the same! There are a lot of potting mixes on the market. Some are good but expensive. Others are cheap but very poor quality and best not used because they can be quite toxic to the plant roots and burn the white root tips (the growing parts that take in water and nutrients).

Good potting mixes are composted for about two months to leach out the toxic tannins in the pine bark or sawdust that almost all potting mixes are made from.  Unless they are private businesses making organic mixes. The dark colour is mainly from the composting operation but can be produced just by applying some Ferrous Sulphate that will blacken the sawdust.   This is done with really cheap potting mix that may be only 2 to 3 days old but this is still raw even though it looks mature.   Super cheap mix will still be very toxic to your plants!!!

However cheap potting mix can be a good filler in some instances – such as needing back fill around a Compot in clay and sandy soil that will eventually be improved over time by the composting process inside the pot and worms outside the pot.

Organic Soil Conditioner

Organic Soil Conditioners

The Organic Soil Conditioners we sell comes from many different sources that are all organically grown or organically fed animals. EG. Pig Manure, Cow Manure, Chicken Manure, Sheep Manure, Zeolite, Rock Dust, and many other secret ingredients go in the mix to create this conditioner.

Because it is not potting mix you only need a small amount to add to your garden or potting mix to improve its quality. Roughly 1kg to 2kgs per linear meter of soil.

Or a pinch to a teaspoon of conditioner, in the hole of a seed you are planting.

Privately made soil conditioners are generally more expensive than store bought potting mixes and include a wider range of ingredients than store bought mixes which are obliged by law to only include a certain amount of nutrients or N,P,K. So you will generally get a better result from privately produced conditioners and require less quantity per linear or cubic meter of soil in your garden. It all depends what you are trying to achieve.

Using soil from inside your Compot

Soil inside a Compot

Using soil from inside your Compot to add to potting mix will greatly improve your potting mix and make maximum use of your Compot by adding free, nutrient rich “Frass” that you created all from your own waste. Wait till it has fully decomposed to increase the volume of your potting mix at no extra cost.   And mix it in well because it is super rich.

Any extra material you add will need to be well mixed throughout your mix, so there are no areas that have lumps of one type of ingredient that might cause large air spaces which could lead to some roots drying, so the plant won’t thrive.

Making “Fines”

If you want to make your own seedling potting mix, instead of buying the more expensive bags of special seedling mix, all you need to do is sieve your existing mix and use the ‘fines’ that drop out of the sieve.

These ‘fines’ can be caught on a piece of plastic sheeting and then tipped into the seedling tray ready for you to plant your seedlings.   The larger bits left in the sieve can be mixed into your normal potting mix.   Some plastic sheeting is useful to have on your potting up bench as a way to collect any mix that falls while potting up a plant. It is caught, kept clean and easy to tip back into your pot, so you do not lose any mix at all, and you keep your potting up bench clean and tidy.

I use the fines to sprinkle over the top of any seeds I am trying to propagate. The fines make it easy for the little seed shoots to poke their heads through the soil to expose them selves to the sun and air.

Repotting a Dendrobium

Bob Repotting a Dendrobium

Cheap potting mix does not have any (or very little) extra fertiliser added to it, but Premium mixes must by law have enough fertiliser added to be active for the next three months.  You can buy cheap potting mix, add some slow release fertiliser, eg Osmacoat, Nutricoat etc.  Mix it in well and then you have a “premium mix” at a cheap price. Or add some organic Soil Conditioner.

Adding fertiliser to your potting mix

Any added fertiliser in addition to any you may have incorporated into the mix, needs to be applied to the TOP of the pot.  The action of water, be it from rain or watering, will move the liquefied fertiliser DOWN with it, NOT up, NOR sideways.  A lot of people are advised to place the fertiliser in the bottom of the pot but all that does is lets the water take the fertiliser out of the bottom of the pot, away from the plant roots. ie. of no benefit to the plant but a lot of profit to the fertiliser manufacturer.

However, if you are planting a big tree or shrub in a hole where you had Compot, you would empty the semi-decomposed contents of the Compot into the hole, top it with a little soil and plant your plant on top of this soil and waste. The undecomposed waste will now break down slowly over time nourishing your plant for a few months as the waste breaks down. It becomes a slow release fertiliser. Some nutrients will be lost to the deeper parts of the soil but many will be readily available for new plant roots to access the nutrients as they grow down into the soil below. So in this instance it is OK to put fertiliser below the plant rather than on top of the soil.

Today’s Did You Know…?

Vanda Orchids

Lots of people think of Orchids as those plants with big purple flowers often used in a bride’s wedding bouquet or in an expensive flower arrangement.

Orchids come in a wide range of colours (including spots and stripes) and a very wide range of sizes.   Some Orchid plants are up to 5 m tall, down to ones that are only a few centimetres tall.   Most grow above the ground but a few Australian native Orchids grow entirely underground in caves in the deserts of central Australia.

Vanda Orchid’s above a water pool

Some of the flowers are a single flower up to about 15 cm wide while others are only half a cm. wide.   Some plants have multiple branches with a lot of flowers on each branch while others are just a single flower.
Some orchids are grown with NO potting mix at all, just an open container with the plant roots hanging down over pools of water underneath them. The water creates high humidity around the roots.   It is only the Vanda type orchid that is grown this way.

In Thailand large commercial growers of Vanda

Plant Roots and Nutrients
What Makes Good Compost?

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