Fruit Tree Pollination

If you want your fruit trees to bear fruit, pollination needs to take place – which leads to fertilisation (mixing of male and female pollen to create new seeds)

Some fruit trees are self fertile, that is, they produce flowers that can be pollinated by their own pollen – like Citrus varieties, Peaches, Nectarines, Apricots, which means you only need to plant one tree and it’ll produce lots of fruit. Other fruit trees, like Apples, Pears, Plums, Cherries, Avocados and some Nuts generally need another variety to cross pollinate with.

Fertilisation is mostly achieved though sexual reproduction, and is pretty much the same as us humans.  Basically, male genetic information  needs to mix with female genetic information to produce offspring. (the new seeds) The difference between us and plants is in the transfer of that information –  Plants can’t move around, so they employ  other creatures (and even the wind) to get their genetic information transferred – mostly bees, birds and other insects (and even some small animals!) – where they attract these creatures using their colour, scent and nectar.

Busy Bees pollinating peach tree blossoms – early spring in the nursery

Once fertilisation has taken place, a seed with it’s own unique genetic material is produced, which is a mixture of both parent plants. The seed is what you’ve been spitting out as you devour the yummy fruity flesh that grows around the seed/s. The characteristics of the fruit (colour, size, flavour) remain the same year after year and is not changed by pollination.  If after spitting out those seeds, a tree grows,  it would differ from the parent tree from which it originated. It might grow into a healthy, lovely tree, but the fruit may be different in many ways – like small in size, with a sour flavour for example.    There are exceptions to this – Polyembryonic seeds, like the Mango , where you can get a seed grown tree that is identical to the mother, therefore producing the same fruit. ( look this up, it’s fascinating!)

Grafted Fruit

But – we’re here for the fruit, which brings us to grafting.  If your fruit trees are grafted, you know you’re getting a cultivated, known, tasty fruit variety. Grafting basically means taking living plant tissue via a cutting from a known variety of plant or tree  and attaching it to another plant of the same variety, usually one that has been grown from seed , or cloned – known as the rootstock. This new variety takes over from the rootstock and you’re left with a lovely tree that bears good quality and size fruit. Grafted fruit trees also are quicker to bear fruit than those grown from seed.

Baby Peaches forming after fertilisation

What about Seedless Fruit?

Seedless fruit can be sterile, forming with little or no seeds and without fertilisation (known as parthenocarpy) Seedless citrus like some lime and navel orange varieties are produced this way.   Other fruits like grapes that are seedless are produced through fertilisation, where the seeds die off, leaving the flesh to grow. (stenospermocarpy). As seeds contain natural growth hormones, commercial growers spray fruit with growth hormones onto their seedless varieties to achieve large fruit sizes.

Successful Fertilisation – Increase your chances of success

The bees  and  birds and other insects pretty much know what to do when it comes to pollination. Our job is to help facillitate this in our backyard orchard. This means, maximising the chances that your trees will cross pollinate. You can do this a couple of ways.

1. Plant trees close to each other – no more than 10 metres apart so that the bees don’t have to travel so far.

2. Provide other flowering plants to encourage bee activity in the vicinity of your trees.  We’ve seen here at the nursery that bees love lavender and rosemary, and also citrus trees –  which  all have long flowering periods. Grevilleas and other native shrubs are usually laden with bees. – This can also backfire – if your bees prefer these to your fruit trees! but we’re working on the assumption that lots of bees in your area are better than no bees, so recommend planting bee attracting plants.  I’m guessing that bees are also opportunistic – last year, we had a beekeeper put a hive on our property as it was in close proximity to a national forest area with native bushland –  where he wanted them to travel to so he could then harvest the honey. Great plan, but the bees didn’t think so – they found blossoms and flowers that were closer to their hive and stuck around here at the nursery! Also, bear in mind that many plants are pollinated by a mix of other insects as well. So having plenty of biodiversity in your garden by using a mixture of plants will encourage these guys in.

3. Make sure you’ve got the correct pollinizers. The main considerations for choosing the correct pollinizers –

a) Flower overlap –  all involved tree varieties need to be flowering for pollination to actually occur. Flowering times can be influenced by the weather, eg – wind blowing off the blossoms, flowering earlier or later due to temperatures.

b) Pollinizers need to differ genetically for fertilisation  eg – a Pink Lady Apple is a cross between a Golden Delicious and a Lady Williams Apple (these are the parents). They’re too closely related and not really suitable.

c) Plant more varieties to increase your chances. Even if trees are self fertile, or semi self fertile, you’ll get a better yield with more varieties.

Pollination chart for Apples, Pears and Plums that we mostly stock in the nursery.

Apples

Granny Smith is a good universal pollinator as it has a long flowering period that can overlap with others.  Ornamental Crab Apples are good all rounders too and are often used in orchards.

European Pears

Ornamental pears like Manchurian or Caleryana type pears can help pollinate fruiting pears.

 Plums

Santa rosa is a good universal pollinator

Fruit Trees for Small Gardens

If you have limited Space in your garden and require two trees for cross pollination, consider planting your two varieties in the same hole. This has a natural dwarfing effect as well as providing pollination partners.   We usually have some double grafted varieties in stock as well for this purpose. Or perhaps try to graft another variety onto your existing variety. You’ll need to find suitable budwood for your variety.   You can also keep many fruit trees dwarf by pruning. Many have shallow roots like citrus, apple and plums and even avocados.  Another great option is to espalier. We see many commercial orchards down this way using this technique to grow their fruit, almost like on a vine.   If you’re really stuck for space, and want to squeeze more fruit trees into your garden, we also have dwarf fruit trees available, which are great for pots or planted in the ground.

Would love to hear about your experiences.  We’ve got a long list of fruit trees to cultivate and so much more to learn – our Nashi and Plum trees need a pollinator, I really want some heritage Apples and want one of each Citrus varieties! Plus, there’s an Avocado hedge to establish.

   *Update Dec 2014 – check out all the Plums ripening up on the tree! The flowers were pollinated this year – Previously, we’d only got about 6 plums.