Let's talk about the Birds and the Bees
Spring (and love) is in the air, so let’s talk about the birds and the bees, or more specifically – plant pollination and reproduction.
Let’s start with pollination. What’s pollination? It’s the act of depositing pollen – the powdery substance that transfers male genetic material – onto the pistil – the female part of the flower. The majority of plants are pollinated via insects (and not all insects are created equal!) or wind. How can you tell? If the plant has a flower that isn’t showy or scented, it’s most likely wind-pollinated. This group contains grasses, corn (also a grass!), various grains (also grasses!), birch, alders, sea buckthorn, and many nut trees (including hazels). Here’s a picture of hazelnut flowers; the male catkins have opened and are releasing pollen, and the female flower is very nondescript.
Plants with showy flowers or flowers that are scented target the insect (and humminbird!) pollinators. Why did I say that not all insects were created equal? Because there are very specific relationships between different plants and different species of insects. Bumblebees are tomatoes’ best pollinator friend, because their large sizes means better pollination success for the large, awkward tomato flower. On the other hand, the tiny sweet alyssum flowers are fantastic for the small native bees, wasps, and hoverflies. Red, tubular flowers are a hummingbird’s paradise, perfectly fitting that long skinny beak. Pawpaw trees have pretty flowers that stink – the tree’s pollinators are flies and not bees!
So – each plant has its own pollinator friend. Whether it’s the gentle breeze, a teeny hoverfly, a bumbling bumblebee, a buzzing fly, or a chirping hummingbird. Why do we need to know? Because of the next section – some plants need not just a pollinating hand (wing?), but also another plant friend. And their reproductive details will determine 1) how many plants you need to have to get fruit, and 2) how closely they should be planted, and in what arrangement.
Now – let’s talk reproductive strategies. Because Ma Nature isn’t a prude and doesn’t judge, there’s a tremendous variety in how plants go about producing plant babies. Some plants – like tomatoes, peas, beans, broccoli, fruit trees (apples, pears, plums, peaches, etc) – have what’s called “perfect flowers” – each individual flower has both the male and the female parts in it. Others, like squash plants, have separate male and female flowers. But the plot thickens further! A single squash vine will have both male flowers and female flowers on it, while plants like kiwis and sea buckthorn will have the sexes completely separate – so you need a male plant and a female plant. So when the fruit ripens, each squash vine will have squash on it (because each vine had both male flowers and female flowers), but only the female sea buckthorn tree will bear fruit!
But wait, we’re not done yet! Some plants have both male and female flower parts (whether in the same flower or in separate flowers), but the plants are genetically incompatible with themselves. For these plants, we need a pollenizer - another plant of the same species, with a different set of genetics, to produce fruit. So if you have a Bartlett pear tree, you’ll need a Bosc or Anjou to get pears, for example. And no, you can’t pollinate a pear with an apple tree – with some (delicious) exceptions, you need to stick with the same species. The plus side is that in this case, both plants will bear fruit, and you’ll get both Anjou and Bartlett pears! This is the case with many fruit trees, including apples, pears, and plums, as well as many nut trees and berry bushes like blueberries, haskaps, and elderberries.
A super-random, super-cool, sexy plant strategy? Take avocados. Each flower has female and male structures, so technically they’re a perfect bisexual flower. But – when the flower first opens, only the female parts are functional, so the flower acts as female-only. It then closes for ~24 h, and reopens as a male flower! And not just that – there’s type A avocados (they’re female in the morning and male in the afternoon next day) and type B avocados (female in the afternoon, and male the next morning), so that you need one of each type to create fruit! Otherwise, the morning birds and the night owls never meet and we don’t get delicious guacamole! Stay weird, avocados, never change.
So tying it all together – you need to find out if the plant you’re about to stick in the ground is self-fertile or needs a pollenizer (or maybe the sexes are completely separate and you need a male and a female)! Would be a shame to plant that beautiful plum tree and watch it flower, but never get fruit, just because you didn’t realize it wasn’t self-fertile.
Then, you need to find out how your plant gets pollinated. If it’s insects, then you’re typically safe – just add some bee-friendly plants around to attract all those pollinators. If your future food-makers are wind-pollinated, the planting recommendation is usually within 30-50 feet between plants, or less if possible. Keep in mind that your planting should reflect the average wind directions. So if typical spring winds for your area are from the east (and to the west) and you plant your trees in a north-south pattern, you might not get much fruit, and we definitely want to avoid that!
Happy planting and fruit-growing, y'all :)