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I was given a gardenia in a pot as a parting gift from a fellow house-sharer a few years ago. I keep it as a houseplant on a bedroom windowsill.

It's looked increasingly sickly since then, but it's bounced back a few times as well. But lately, nothing I do seems to stop it shedding leaves and withering away. It now only has a few left.

I have noticed that there are crawling bugs in the compost - tiny ones. Since I'm sure I've solved all the other problems it might have had with its environment (soil fertility, acidity, humidity, temperature) I have a feeling these bugs are probably eating its roots.

What can I do to get rid of them?

edit #1:

Adding a picture of the plant as it currently survives. A sorry state indeed.

enter image description here

Note the streak of yellow along the veins of the leaf in the foreground; that came on extremely fast; a matter of days. Furthermore, after the dunking treatment I described yesterday, the same discolouration has noticeably receded on some of the other remaining leaves; this is in under 24 hours.

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    need a picture of the plant and a closeup of the insects. Some soil insects are harmful and others are not. – kevinsky Nov 3 '13 at 13:08
  • I don't think I have a camera that would clearly resolve something that small. I'll try and capture one and compare it to some photographs, maybe that will help. It's almost embarrassing to post one of the plant because of the awful state it's in, but I'll give that a go. – Tom W Nov 6 '13 at 13:26
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I note you are in the UK, so the likeliest explanation is either root aphids or fungus gnats (if you notice black specks flying about as well). Either way, there isn't much available to treat these with any more, so it's going to have to be the old fashioned method. It's a pity it's winter now, because really you need to do this outside, but what you do is get a bucket of water, about half full, take the plant out of its pot, shake off or remove as much compost as you possibly can, then put the rootball into the bucket (without immersing the foliage). Leave it for a while, then go back and give it a shake - what you're trying to do is get off all the compost, preferably without losing roots, leaving just root material, which often means a couple of changes of water and 2 or 3 hours. Once you've managed it, repot into a clean, sterile pot using new ericaceous compost. It would actually be better to do this in Spring, but if the plant is sickly, then it probably can't wait. In the meantime, check any other houseplants you have to make sure they are not similarly affected.

UPDATE: I've only just noticed how you're drowning the plant - that isn't what I'd call drowning, immersion in a bucket up to the stem base is what I'd call drowning. If you've noticed an improvement already, that's much more likely to be the plant taking up water - it may have been too dry throughout most of the rootball. It does look a very sorry state, I must say.

  • Thanks. I had read somewhere that for some infestations, drowning by slowly saturating the pot inside a larger container can work, particularly if the rising water level is slow enough that it forces the population to flee. I have also read that gardenias in particular dislike having their roots disturbed, so for all I know this will finish it off, but I think I will just re-pot it as suggested. – Tom W Nov 6 '13 at 13:28
  • Well you could certainly try drowning it in a bucket to see if that does the trick, but I'd 'drown' it a second time in clean water. Be interesting to see what, if anything, comes out. – Bamboo Nov 6 '13 at 13:36
  • Well, am simulating a flood now. There are definitely quite a few tiny grey jumping bugs escaping. – Tom W Nov 6 '13 at 21:37
  • Might do the trick then, saves disturbing the rootball – Bamboo Nov 7 '13 at 15:52
  • It might be wishful thinking, but I swear some of the yellowing on the leaves has receded since about 24 hours ago. I can well imagine that if I've killed a significant proportion of whatever was sucking its sap, it'll suddenly lurch into life. If it does that, I'll keep an eye on it and hope it recovers. If it doesn't, I'll resort to phase 2 and hope it pulls through. – Tom W Nov 7 '13 at 21:51
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My recommendation is to throw that plant away. The bugs are just a symptom of a much larger issue. If I had to guess, I would say that the root system has died from over watering and it has been starved of energy from lack of adequate light.

However, if you decide to try to salvage it (which I don't recommend) here are the steps that I would take.

Take the plant outside and remove it entirely from its pot. Wash all of the dirt off of the plant. Trim off all dead portions of the plant back to living tissue. If you don't see any living roots then throw the plant away. Seriously, it's dead already and these are just its death throes. If you do see living roots (probably white and fuzzy) then repot the plant in a new pot larger than the old one with brand new potting soil.

Once it's repotted, water it well and place it in an area where it gets filtered sunlight for a minimum of 4 hours per day. That should give the plant the conditions it needs to recover. Once it has produced green, healthy growth then I'd move it to a location where it gets a minimum of 6 hours of direct sun a day.

Do that and it will thrive.

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