Plant Compatability as Natural Insecticide

Including aromatic plants and herbs around the garden, to act as pest deterrents.



Well, yeah, certainly this can deter insect pests, but 'most' aromatic
plants will just sit there minding their own business. In order for
these plants to be effective, they need to be in high traffic areas,
where either they are being walked on, or brushed against everytime
someone passes by. The plants must be disturbed in some fashion - such
as crushed leaves and branches, or indeed the breaking of roots- in
order to stimulate the release of the aromatic oils.



As an experiment, plant a citronella geranium in your outdoor
entertainment area. For that matter, plant 20 of them - unless you are
actively bashing these plants every now and then - you are still going
to be attacked by mosquitoes.



Similarly, marigolds are said to be good for getting rid of nematodes.



Well now, this is quite true, but - it is a particular variety of
marigold that is best at achieving this. Not the lovely heavy-flowering
varieties, so attractive in the garden, no such luck.
In fact it is Tagetes minuta, or Stinking roger. You would NOT plant
this on purpose. It can grow to 12 feet, a magnifying glass is needed
to see the flowers, and the miniscule seed is shed anytime the plant is
disturbed - by the thousands. Not only will this plant out-compete
everything else in the garden - it can and will take over.



Let's have a look at mint. Highly aromatic and hardy, can be used as a
living mulch in high traffic areas. However, The only mint I would use
is Mentha pulegium, or Pennyroyal, as it grows on the surface of the
soil and is relatively 'soft'. Most other mints, notably Mentha suaveolens, or Apple mint (sometimes
called woolly mint), and Mentha spicata, or Common mint, are worthy plants
in their own right, plant them in high traffic areas, however, and
you've got trouble.



These plants can reproduce by seed, but most notable is the speed at
which they send out runners - all across your garden, and deep, looking
for areas of no traffic and moisture. This means IN your garden. Often
travelling UNDER your plants, so once established, is not any easy
beastie to get rid of.



It is often propounded that these mints will grow in poor soil areas
and don't particularly 'like' rich soil. Well, plant some in your
compost-heap and see how that works for you!



Personally, I would only plant it: in a concrete pot, sitting on concrete, preferrably on someone else's property.




Some plants do, however, exude their aromas without any help - carrots
and the onion family spring readily to mind, all they need is a bit of
sun.


For the most part, this type of 'insect control' is that of a 'deterrent'. Nothing more.