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Archive for the ‘Pots’ Category

Lots of people think that all you have to do to grow in pots is grab some of the backyard soil and chuck it in a pot and Hey Presto!  But growing in pots is way different to growing in soil in the ground.

Confined space:  pots have sides and a bottom.  This restricts root growth and decreases the volume of media from which water and nutrients can be extracted.  Temperature fluctuations may be far greater in a pot.

Having a restricted root area in a pot is not necessarily a bad thing. Much better to have that ornamental Ficus in a pot than in the garden where it will seek out water leaking from any drainage/septic system and quickly grow towards and into it and clog it up.  And if you water frequently and feed well the top will grow and do so quite happily despite looking out of proportion.  So plants in pots will need more frequent watering than those in the garden.  If you have particular reason for wanting to keep plants long term in a pot then look at some of the more innovative root or air pruning designs such as rocket pots   or anti spiral pots .

The size and shape of the pot also plays a big part in how well (or not) the pot drains.  Tall thin pots drain better than wide shallow ones.  While we are on drainage,  NEVER sit keep your pot in a saucer filled with water.  You will get a perched water table (a soggy bottom) into which no roots will want to venture.  Zero aeration, reduced forms of nutrients which can be toxic and a high probability of root rot.  Plus if that drained water is never thrown away what you are essentially doing is recycled hydroponics without periodic leaching (throwing away the wastewater).  Some of the stuff that leaches out of the bottom of pots is unwanted and unhealthy as far as the plant is concerned.  Yes there may be nutrients in it but there’s also other nasty stuff.

Invariably, media for pots needs to be better aerated than soil.  As far as potting media goes you generally get what you pay for.  There is an Australian standard for retail potting mix.  Look for it as it means quality.  The pH will be good, it will be well formulated, well aerated and not toxic. Cheap potting mixes may be made with ingredients like sedge peat that look nice and black but are way too fine and just totally unsuitable for pots.  Cheap potting mixes have no guarantee of a suitable pH, may carry disease, be salty, devoid of any nutrients or if they contain relatively fresh wood chips or sawdust, can actually drawdown nutrients and take them away from the plant.  Mixes made from uncomposted manures and woody materials will be very dynamic, with large swings in pH shrinking in volume over time decreasing aeration and becoming easily waterlogged.  Your plants deserve better!

Potting mixes are dynamic.  Over time they will degrade and that is partly why you need to re-pot every once in a while.  Ingredients like pine bark will deteriorate and shed fine particles that can silt up the sides and base of the pot, decreasing drainage and aeration.

A few pointers on pots

  • Watch for pots with tops that taper in at the top – think ahead to when the root ball has filled the pot and you need to get it out to repot – and have to break the pot up to do so!
  • When you buy pots have a look at the drainage holes in the bottom.  Often they are inadequate – don’t be afraid to drill more.  And watch if the base of the pot is completely flat – think about how any excess water will get out – either buy a different pot or recognise you will have to place it on some sort of support that will permit it to drain.
  • Don’t over pot.  Putting a small plant in a big pot doesn’t do the plant any good.  You will have a large volume of potting mix that will be unexplored, go sour, be cold and generally yuk.  Much better to pot in a smaller pot and then repot later.
  • Never fill a pot to the brim with mix.  Leave a couple of cm at least, to act as a temporary reservoir when you water.
  • Think about the stability of your pot and the mix in it – Perth’s howling Easterlies are one good reason to have more sand than polystyrene in your pots!
  •  Black pots tend to last longer than coloured pots, especially light ones.  They do get hotter but because no light can penetrate, the roots explore more volume.
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