0Controlling pests on indoor plants

I grow tomatos, cucumbers, chillis, lemons and olives in a south facing conservatory.  Over the last 5 years I’ve suffered with a range of vermin attacking my plants, it seems to be a different type of pest each year after I’ve conquered the previous pest.  Below I cover a few successful ways I’ve found to control a range of pests.

General advice

I’ve found that some varieties of each type of plant are much more resistant to vermin than others.  For example the F1 Aji Limon chilli peppers don’t seem to be targeted much by any vermin, so I now tend to grow these rather than other chillis.  If all else fails then I recommend looking at the varieties you are growing and try some different ones.

Red spider mite

Red spider mites are one of the worst pests as they seem very difficult to destroy.  They are fairly resistant to most sprays and treatments.  I have found a few approaches effective.  The first is to grow a few pots of chives both inside the room, and in the garden.  Red spider mites apparently are repelled by the smell of chives.  The second control I have used is predatory mites that eat red spider mite.  Red spider mites also like a room to be dry and hot so I have allowed the room to get colder at night (e.g. by leaving a small window open).

Greenfly & Blackfly

Greenfly and blackfly are common pests that can attack most plants and multiply extremely quickly.  However they are realtively easy to kill.  Mild soapy sprays easily kill them off, but to avoid using even this I usually obtain some ladybird and lacewing larvae around April-May and these will eat through greenfly in short order.  Greenfly and blackfly also don’t like direct sun so I have replaced my drainage trays with light coloured ones and repainted the room to a lighter shade so that more reflected light hits the underside of the leaves.


Thrips are also eaten by ladybird and lacewing larvae so the same treatment for greenfly and blackfly seems to help keep thrips under control.  Keeping a window open also allows the adult ladybirds and lacewings to escape into the garden where they will hopefully help to increase to local outdoor population, which in turn should reduce the supply of new pests in future years.


I’ve had these on my lemon tree but not on anything else.  They are particularly fast at reproducing, and seem to attack the forming fruit, killing it off.  They can be dealt with by a range of biological controls including ladybirds and lacewings.


This year I’ve had scale insects on my olive plant.  As with all pests I have initially treated them by picking them off and squashing them.  There are 3 varieties of parasitic wasp (Metaphycus helvolus, Metaphycus bartletti, and Scutellista cyanea which are all harmless to humans) that will control scale insects.  The first 2 of the 3 are only suitable for indoors, whilst the 3rd doesn’t seem to be widely available.  They are most effective with soft scale insects.  Hard scale insects are best addressed with a type of ladybird – Chilocorus nigritus.

General advice

The large majority of pests seem to be susceptible to ladybirds, lacewings, and predatory wasps.  The best thing for your garden is to support natural populations of these helpful insects by providing them with access to a suitable habitat and water.

What next?

I’m anticipating yet another new pest next year, perhaps I’ll get some vine wevils on my outdoor grape vine.  Whatever comes I’ll be ready.

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