Cherry trees are usually among the more reliable flowering trees in terms of producing that abundant bloom in March or April. And short-lived as it usually is, it’s one of THE most spectacular displays in the world of arboriculture. Driving to work at that time of year, it’s usually tree after tree of beautiful pink blossoms.
But, we live in the real world, and sometimes cherry trees do not bloom like they’re meant to. My first cherry tree (planted 10 years ago) barely flowered – what was I doing wrong?
So why is your cherry tree not flowering well, and what can you do about it? How can I make it bloom?
Cherry trees will not bloom for their first 2 to 10 years, depending on variety and propagation method. In established trees, poorly timed pruning and harsh late frosts can prevent flower formation. Soil, nutrients, sunlight, irrigation and biennial bearing patterns also affect flowering.
I’ll unpack this below, in detail. As always, I’ll aim to give you the most complete answer on the internet based on my hands-on experience and the in-depth research I’ll do for you.
How old are cherry trees when they start blooming?
Firstly, be aware that you may not be doing anything wrong – cherry trees don’t bloom until they start to mature, and there are some pretty large differences in when this happens based on the species and cultivar of cherry tree that you’re dealing with. There are two main species of cherry, but there’s a confusing array of names to call them by – Prunus cerasus or ‘sour cherry‘ is also known as ‘acid’ or ‘tart’ cherry, and Prunus avium is known as ‘sweet cherry‘, but also called ‘wild’ cherry or ‘bird’ cherry!
Then you’ve got many, many cultivars of each that can be purchased and grown ornamentally – Prunus avium ‘Black Republican’; Prunus cerasus ‘Montmorency’ for example. As well as the time taken to bloom, the size, colour and number of flowers will vary from one to the others – some are cultivated for the quality of their fruit rather than that of their flowers.
So this explains why there’s quite a large variation in the age at which cherry trees start blooming, with two cultivars often being different. In general though, sour cherry varieties will bloom at a younger age than sweet cherries. When planted from seed, this might take around 4 years for sour cherries and eight for sweet ones.
Cherry trees bought from nurseries are not usually grown from seed, however. There’s a good chance they’ve been grafted – meaning an upper part (scion) of one tree was attached to the lower part (rootstock) of another tree with different qualities, so that the tree that subsequently grows has a mix of both qualities – for example, better fruiting potential or better resistance to cold weather. If you look at the base of a young tree, you might be able to see a line in the bark where the join was originally made.
Grafted trees get a headstart over those grown from seed, so will often produce flowers (and fruit) after just one or two seasons.
If you’ve bought a cherry tree in the last couple of years, it might be a good idea at this point to call the nursery and try to find out the name of the cultivar. They may be able to tell you how long it’ll usually take to bloom.
How does pruning affect cherry tree flowering?
Quite considerably! The timing of the pruning is the main thing. I’ve seen a number of cases where the owner has attempted to shape their tree, and cut off branches that had the very buds that would have turned into flowers. For this reason, owners who are prioritizing flowers should wait until spring blooms have gone before they get the secateurs out. It may even be better to wait until the late summer, particularly in the case of sweet cherries, which are susceptible to bacterial and fungal diseases.
It’s possible to tell leafing buds from flowering buds. Flowering buds are generally rounder and fatter than leafing buds – thinner, with a sharp point. Flowering buds might be in groups of two or three. Often there will be more leafing buds on the tall central stem.
If you’re interested in pruning cherry trees in general, here’s a really simple and helpful video.
Weather and cherry tree flowering
While cherry trees are generally ‘hardy’ – they can survive cold weather. Sour cherry trees grow best in USDA hardiness zones 4-6, meaning regions where there is an average annual minimum winter temperature of -30 to -25 °F (-34.4 to -31.7 °C) up to -5 to 0 °F (-20.6 to -17.8 °C). Sweet cherries prefer it slightly warmer, in zone 5 to 7, where there’s an average annual minimum winter temperature of -20 to -15 °F (-28.9 to -26.1 °C) up to 5 to 10 °F (-15 to -12.2 °C). You can check your hardiness zone in the US via this link to the USDA’s hardiness zone map.
If you’re in the UK, the vast majority of cherry tree cultivars will survive just fine throughout the UK.
Survival doesn’t necessarily = good blossoms though. Even if the tree makes it, some of the delicate parts can suffer in frosts. Cold snaps that cause frosts at the wrong time, particularly in the late spring, can kill off a cherry tree’s flowering buds and therefore its potential to flower that year.
Of course, if there are no flowers, there’ll be no fruit either. So in commercial cherry production, frost is a very important consideration, and measures can be considered to protect cherries and other fruit trees from frost. If you’ve got a small tree and frosts are expected when there are already round, fat, flowering buds on the tree, you can try to wrap or cover it with plastic, hessian or horticultural fleece.
Here’s a simple method demonstrated on YouTube. It’s not hard work and it could easily be worth doing, so you aren’t disappointed when it comes to blossoming time.
On the other hand, an usually warm winter can set back flower production. Cherry trees (in common with other fruit trees) need cold weather in the winter to trigger their natural progression into springtime growth. According to the University of California Extension, cherry trees have high chilling requirements – they need to be exposed to a temperature below 45°F (7°C) for 700-800 hours (for sweet cherries) or over 1200 hours for sour cherries.
Here’s a link to a map provided by the US Dept of Agriculture. It’ll show you how many ‘chill hours’ can be expected in various parts of the United States.
Year-on-year flowering variation
Some cherry trees are biennial bearing, which means that they have a tendency to produce an abundance of flowers one year, and an abundance of fruit the next. This is more common in young trees, and tends to become less marked as they mature.
But there’s data to indicate that even in the same regions, the same trees can vary their flowering behaviour year after year, because of local climate. The Environmental Protection Agency (EPA) has published the National Cherry Blossom festival’s ‘peak bloom’ dates since 1920. Interestingly, their graph shows that over a 5-year period, there can be almost a month’s variation over the date of peak blooming each year. The EPA has also pointed out that cherry tree blooming appears to be getting earlier over the years, and that this may be related to rising global temperatures.
Soil, sun, water and cherry blossoms
Like all trees, cherries have their preferences for their growing conditions on each site. Anything that makes your tree grow poorly will likely mean it blooms disappointingly as well.
Cherries like deep, slightly acidic soil (pH around 6.5) that’s well-drained, and don’t grow as well in poorly trained, waterlogged areas. Like many fruit trees, they prefer to grow in an open location with full sun (although sour cherries will often tolerate a bit of shade, and might do OK near a north-facing fence).
Cherry trees don’t usually need much watering when they’re mature, but can dry out quite considerably when they’re in the first couple of years since planting. It’s important to give young trees a good soak once or twice a week during any dry spells.
When watering the tree, avoid simply blasting at the base of the tree with your hose. The roots usually lie in a similar pattern to the branches above. Think about it as if you’re simulating rainfall – a 5-minute sprinkle is unlikely to get water to the deeper roots (any more than a 5-minute shower will). 20-30 minutes ought to do it.
Fertilizing cherry trees again is not usually mandatory, BUT if you’re having a flowering problem, it might be to do with a certain nutrient imbalance in the soil. Most fertilizers contain a balance of Nitrogen, Phosphorus and Potassium (called NPK) and will be labelled in accordance with their respective proportions, e.g. 10-10-10. Soils that have too much nitrogen can stimulate a lot of leafy growth, but not many flowers. Fertilisers that are specifically designed to stimulate bud and bloom production might be worth a try. It’s important to follow the manufacturers directions – applying too much can have the opposite effect.
It’s quite easy to test both the pH and the NPK content of your own soil, using a home kit. You can purchase these online. I use the Rapitest soil testing kit… every gardener must know their soil, right?
I hope you’ve found this guide helpful. Here’s hoping you’re on your way to better blooms next season… there really is nothing quite like cherry blossom time!