Growing apple trees yields delicious fruit, and saves you money on apple varieties you couldn’t find at the store. To achieve this bounty, though, it’s important to understand apple tree pollination. Even if you’re brand new to growing your own apples, this guide will help provide the knowledge and confidence you need to get started. The process is simple, and the bees and the trees do most of the work!
In this complete guide to apple tree pollination, you’ll learn:
- How Apple Tree Pollination Works
- Apple Tree Relationships & Compatibility
- Good Pollinator Partners
- Alternative Ways to Pollinate Your Apple Trees
- Why Your Apple Tree Isn’t Bearing Fruit
How Can I Cross-Pollinate My Apple Trees?
How Apple Tree Pollination Works
The act of plants exchanging pollens in order to propagate is called cross-pollination.
While a variety of insects, animals (such as humans), and even wind can facilitate cross-pollination, the primary pollinators of apple trees are honeybees. Mason bees and bumblebees also play an important, although slightly smaller, role in successful apple tree pollination.
These pollinators are most active when the environment is suitable for them. Bees prefer 65° F weather, free of rain or strong wind gusts. Installing pollinator-attracting plants is a great way to encourage hive development and bee activity in your home orchard.
It’s also important not to apply pesticides to apple trees around the time of apple tree pollination, as these are toxic to bees and will deter them.
The final important variable in natural cross-pollination is the proximity of your apple trees to one another. Bees prefer to stay within an accessible distance from their hive, so it’s important that apple trees are planted within 100 feet of one another.
The optimal time for apple tree pollination is during a tree’s bloom period. This is the time span during which an apple tree blossoms, producing flowers.
Different kinds of apple trees have different bloom periods. Bloom periods are usually described as early season, early mid-season, mid-season, mid-late season, and late season. Blossoms from neighboring trees must be completely open, simultaneously, in order for apple tree pollination to occur.
You’ll experience the most success nurturing your apple trees to bear fruit if the varieties you plant have the same bloom period.
Peak Blossom Days
Some guides advise gardeners to adhere to peak blossom days. However, there is no uniform documentation of peak blossom days that every gardener can utilize.
Blossom periods vary between regions, largely due to climate-related factors that accelerate or decelerate apple tree development. Additionally, seasons can behave differently from year-to-year, creating fluctuations in conditions that affect tree growth and apple tree pollination.
There are also differences in climate between continents. Much apple tree blossom data originated in the UK, which has more gradual spring-to-summer transitions than the majority of the USA.
So, while it may seem more accurate to aim for pollination on peak blossom days, it is actually most effective to focus on consistent bloom periods.
How Do I Choose Compatible Trees?
Apple Tree Relationships & Compatibility
As with many organisms, apple trees grow to be most healthy and bountiful whenever they experience genetic diversity. Simply put, it’s important to cross-pollinate apple trees with varieties that, rather than closely-related, are genetically distinct from one another.
An example of cross-pollinating compatible apple trees would be avoiding pollination between two Gala apple trees, and encouraging cross-pollination between a Gala variety and a Fuji variety.
Family relationships in apple trees discourage cross-pollination. For example, Honeycrisp is a hybrid of the Macoun and Honeygold apple cultivars, and is not recommended for cross-pollination with those varieties.
In most cases, traditional apple trees from the USA will not be closely related to traditional apple trees from Europe. That said, cultural exchange has produced some varieties of apple trees that bridge the family groups on both continents.
Rootstock refers to the stem and root system of a parent plant, which can have a new plant grafted onto it. Some apple trees begin with a nursery-grown rootstock before being planted in the ground. Crabapple rootstock may be used to provide beneficial, fortifying qualities to orchard apple trees.
When choosing apple trees to cross-pollinate, remember that rootstock affects bloom periods. Before selecting your apple tree variety, note whether any rootstock you are choosing delays or expedites the bloom period.
Choosing Your Desired Apple For Apple Tree Pollination
Apple varieties are measured on a sweet-to-tart spectrum. Sweeter apples tend to be used as dessert apples, while tart apples are usually best-suited for cooking. Apple varieties in the middle of the spectrum can be used for a variety of purposes, or enjoyed fresh, at your discretion.
You can choose which apples you’d most like to grow based on their described qualities and, most importantly, their taste. It may benefit you to keep your local climate in mind, developing an understanding of your regional seasons as to better choose apple trees that will bloom at ideal times for propagation.
Finally, you can prolong your home-grown apple enjoyment by planting some trees to bear fruit for immediate consumption, and others to bear fruit that can last in storage.
How Can I Know a Good Pollinator from a Poor Pollinator?
Good Pollinator Partners
Apple tree pollination is most successful with good pollinator partners. The best pollinators are genetically diverse from one another, and can improve the health and flavor of the fruit and seeds they create.
Some examples of great pollinator partners include:
- Golden Delicious with Fuji, Granny Smith, or Honeycrisp
- Honeycrisp with Gala, Pink Lady, or Red Delicious
- Red Rome with Golden Delicious, Ozark Gold, or Yellow Delicious
Pollinating with Crabapples
Crabapples are a group of apple trees which bear fruit that is roughly two inches or less in diameter.
Crabapples flower in abundance, and thus produce large amounts of pollen that can encourage apple tree pollination. There are numerous crabapple varieties to choose from, each of which can offer unique qualities and resiliencies to your apple trees.
While crabapples are great pollinators in general, there may be specific apple varieties that produce better apple tree pollination results depending on the apple trees you choose.
Poor apple tree pollination is usually resultant of an apple tree’s ploidy. Ploidy refers to the number of chromosome sets that an organism possesses. Humans have two sets of chromosomes. So we, like most apple trees, are diploid.
Some apple trees, though, are triploid. Apple trees with three sets of chromosomes do not pollinate diploid apple trees. In fact, triploid trees require two different compatible diploid trees in order to cross-pollinate.
While some triploid trees are self-fertile, meaning that they can bear fruit without cross-pollination, they still produce less fruit (and lower quality fruit) unless cross-pollinated.
Additionally, inhospitable whether conditions will render self-fertile trees self-sterile. Cross-pollination enables you to avoid barren seasons, as well as bitter pit. This fruit disorder is characterized by a calcium deficiency that produces brown spots in the skin and flesh the apples.
Some triploid apple varieties are: Jonagold, Gravenstein, Baldwin, Mutsu, and Ashmead’s Kernal.
Although triploid trees do not pollinate other trees, they do produce tasty apples. This is why some gardeners decide that triploid varieties are worthwhile additions to their orchard.
What Are Alternative Ways to Pollinate My Apple Trees?
Grafting involves attaching a good pollinator onto a lesser pollinator. The good pollinator is referred to as the bud, or scion, and the lesser pollinator is the rootstock base. Grafting increases the propagation of your apple trees.
If grafting doesn’t appeal to you, you can attain a similar effect by placing fresh, blooming bouquets of good pollinators into a bucket of water. Hang the bouquet-in-a-bucket from the branches of apple trees with lower pollination levels to encourage better apple tree pollination.
Pollinating by Hand
If your area doesn’t have a sufficient pollinator population, or if your selected apple tree varieties aren’t blooming simultaneously, you can pollinate your apple trees by hand.
Simply purchase your desired apple tree pollen, or collect ripe pollen from your own trees before the flowers open. Then, using clean hands and implements, apply the pollen directly to the unopened flowers of your non-blooming apple tree. Seal the pistils, the stalks attached to the ovaries at the center of flowers, with surgical tape after pollination.
If you’d like to maximize the number of pollinators in your area, you can find a variety of pollinator-attracting plants to add to your orchard.
Why Isn’t My Apple Tree Bearing Fruit?
Trees that create flowers, but not fruit, may be experiencing poor pollination. Especially cold weather (below 55° F) during the bloom period can discourage pollinators and delay blossoms. Gardeners living in colder climates can invest in cold-tolerant apple trees, like Red Falstaff or Spartan, to offset this effect.
Taking advance measures to protect your trees from freezes can help reduce flower loss at extreme temperatures. Additionally, gardeners can choose to produce late blooming apple trees, such as Braeburn, so that the bloom period is unaffected by unusually cool weather.
Apple trees that lack flowers may be too young to set fruit. Dwarf and semi-dwarf varieties require three to five years to flower and bear fruit. Standard orchard apple trees may take as long as five to 10 years. Creating flowers and bearing fruit are features of mature apple trees, so have patience if your young ones are still growing.
Heavy soil, a lack of sunlight, and other poor growing conditions can result in poorly growing trees. Without good health and the proper conditions, a tree will not have the strength to form flowers.
Now you’re equipped with the knowledge to start planning your own apple orchard. Proper temperature, tree spacing, and thriving pollinator populations are essential to successful apple tree pollination. Selecting varieties that bloom in alignment with your region’s balmy weather can help you enjoy the tasty home-grown apples you’ve been dreaming of.
Read more about apple trees to continue developing your expertise. Happy growing!