of pollinators and weeds in compost
I know there has been a lack of bees this summer, but I have also
noticed a lack of female blossoms on my cucumbers, melons and zucchini.
I was prepared to hand-pollinate, but with only one or two female
flowers on the latter two, I was very disappointed.
My other problem is with
weeds. Since bringing in compost and potting mix (I have tried several
different brands), I have noticed a proliferation of weeds, some
that I had not previously seen on my section. Nut grass, hydrocotyle,
milkweed and numerous strange grasses and unidentified groundcover
weeds. I've never seen paspallum here either - my lawn is all kikuyu
- but there is paspallum in my cultivated areas. Are compost and
potting mixes sterilized? Have other readers experienced these problems?
seem to have had the same problem as me this year. The lack of female
flowers on the plants is annoying, and there are a couple of factors
that cause this. One is high rainfall. The high level of rainfall
we have had can cause leaching from the soil of important nutrients
like potassium, which is used for efficient flower development.
Rain also carries a
large amount of nitrogen in it, so this can also cause an imbalance
with nutrients. The way to counteract this is to feed the plants
with a good fertiliser like Yates Thrive Flower and Fruit. It has
a higher potassium rate, which encourages flowering and fruiting
development. It has a lower nitrogen rate so you don't have a lot
of leaf growth.
The introduction of weeds
onto your property seems rather large, and could be caused by many
things, such as wind or birds as well as unsterilised compost or
A lot of weeds will be
coming into seed soon, so this will increase the number of new weeds
germinating before autumn. Another common reason for the increase
in weeds is due to you cultivating the soil. The seeds are brought
to the surface and the light, warmth and moisture on them makes
them germinate. Some seeds can last in the soil for many years,
so this is why you get weeds or plants growing that you may not
have had around your garden for many years.
When most composts and
potting mixes are made, they are not sterilized with chemicals,
but with heat that is generated in the stacks during production.
These temperatures can reach up to 75°C.
Gardener, Issue 94, 2002, Page 22
Reproduced with permission from the former Weekend Gardener magazine. The views expressed here are not necessarily those of the RNZIH.