how many years.. have you been using the same media in that pot???

if its more than a couple.... you ought to change it regardless of these things ...

and is it media.. or soil/dirt ....

ken

Hi no more than 2 years. Always mix in fresh Multi-purpose Compost with fertilisers etc. We don't have any dirt etc as it is a concrete yard, so all soil is purchased from a garden centre

Also, I am intrigued why you need to completely change pots, as you don't change the soil in a garden? This stuff remains there for decades? Just intrigued that is all.

Hi I'm taking it no one can help with the identification of this?
After registering, I assumed someone would know?

Those are the larva of one of many insects (a general term for a multitude of things that fly around) and most likely came from eggs the parent laid in the growing medium during the season. It is difficult to identify since many of these larva look much the same. The only reason to bin that potting mix would be because it contains a disease pathogen. These larva will probably reappear next year as well.

Dreamer, no one has answered because your question hasn't been spotted by someone who knows. The longer it stays at the top of the page, the more likely someone will be able to help. A post begins to drop as soon as someone posts a comment, even you.

I would strongly suspect that they are Dahlia root maggots. Do some research about how to avoid them in the future. Sorry....I didn't see the post until now.

Potting mix, or anything used to grow plants in a container, is not comparable in any way to real garden soil happily situated as part of the earth. "Dirt " is constantly being renewed and restored. There are no walls, no bottom. Micro and macro fauna abound, all part of a highly complex, working system.....the soil system.

Potting mix of any kind is inert, dead. It needs to be changed because it can't renew itself within the confines of a container. The ingredients from which it is composed begin to physically break down, deteriorate.

As time passes, the characteristics we like about the potting mix we have chosen end up eroded. Porosity is lost. Some options last longer than others, but all must eventually be changed out or the plants will pay the price.

By the way, if you were to use your finest native garden soil in a container, it, too, will turn into sludge when it's taken out of that whole system of biological, chemical, and physical interaction.

the short version of rhiz explanation..

potting medias number one roll.. in my world.. is water management ... allowing it to flow thru.. retaining what is needed[depending on your choice of type .. e.g. cactus vs tree vs annuals..e tc] .. and shedding excess ...

over a few years.. as rhiz states.. it start breaking down.. and then it gets real hard.. to manage the water.. your plant needs..

so every now and then.. it should be changed out...

on some level.. you are doing that by refreshing it ... but a full change.. ever few years wouldnt hurt... as the media can also start building up retention of salts ... unused ferts... are salts...

and.. there go the bugs.. whatever they may be..

ken

Actually, ken...."every few years " is not often enough! The typical soil-less potting medium should be changed out every year, in my opinion. The one I happen to use is much sturdier than most, being composed largely of conifer bark fines, but it still becomes less porous than I like after several months.

It is possible to use a large percentage of inert ingredients such as perlite, turface, granite grit, diatomaceous earth conditioner (not the same as the stuff used to control pests), etc. Those are the components of a longer lived medium, and are used to build a good structure for a bonsai specimen. But even then, the sharp edges can wear away from those little pieces after some time, necessitating a re-pot and root pruning.