Ask John Negus

John has been answering reader queries for 49 years

Will my avocado flowers become fruit?

Q I think this is a flower on my avocado tree. If so, what are the chances of fruit appearing? Mrs. M Wright, Southrepps, Norfolk

A You definitely have a flower on your avocado, which is wonderful! However, whether you get a fruit or not is rather complicated.

Avocado flowers are hermaphrodite, having both male and female reproductive parts, but they bear two sorts of flowers known as ‘A flowers’ and ‘B flowers’.

In each, the male and female reproductive parts are active at different times of the day so the plant may be releasing pollen in the morning and receptive to pollen in the afternoon, or vice versa.

This means that the chances of the flowers being pollinated are slim and the best chance of success is to have two or more plants. However, avocado growers suggest that a single tree gets more productive the older it gets, regardless of having a pollinator or not. You could also consider pollinating by hand.

Flowering and fruiting are also dependent upon temperature. At a steady 70ºF (21ºC) day and night, flowers will maintain their complicated activity as described above.

Below 60ºF (15ºC) the flowers are unlikely to produce or be receptive to pollen. At 65ºF (18ºC) you may confuse the plant enough that it drops its complicated routine and produces pollen at the same time as being receptive. Good luck!

Is it too early to sow petunias?

Q Is this the right time to start sowing petunia and how do I sow them successfully? Howard Taylor, Halifax, West Yorkshire

A December may be too early to sow in your part of the UK, bearing in mind that unless you have hardening-off facilities it could be late May before you can safely plant out your young petunia seedlings.