There is a lot of confusion around which fruit trees need a partner in order to cross-pollinate and produce fruit. Some trees are self fertile such as citrus, others are partially self fertile like some avocados and almonds, then there are those such as apples and plums that need a different variety that flower at the same time in order to develop fruit.

Confusing I know, but once you have the gist of it all it will be pretty clear. Most nurseries that sell fruit trees will have labels that will tell you of the suitable pollinator plant for that variety.

Self-pollinating fruit trees (meaning you only need one):

All citrus, most figs, apricot, banana, elderberry, guava, loquat, logan, lychee, mango, medlar, mango, mulberry, nectarine, peach, pomegranate and quince.  Avocado could also be included on this list, Hass, Fuerte and Reed as long as you have many bees around to do the pollinating for you.

Partial self pollinating – (meaning it will fruit with only one tree, but often does better with two)

Cherry  (Stella and Sunburst) Feijoas, and astringent Persimmons

Pollinator required 

This applies to almonds, apples, pears, plums, cherries, sapote, custard apple, carob, pawpaw, lychee, and non-astingent persimmons.

Apples 

Pears 

Plums 

There are many nurseries that specialise in fruit trees where you can obtain all the information on selecting the right tree for your climate, soil type and size of garden. Bare in mind some fruit varieties are better suited to different chill factors so be sure to check if they need a sustained cold winter (high chill) or milder winters (low chill) which have few nights below 5 degrees.