15 March 2025   in orchard by Mark Evens

How to monitor the development of blossom

When spring is coming and those blossom buds are starting to swell, it's interesting (well, interesting to me anyway 🤓) to monitor the development and try and estimate when the blossom will be out. In my case, I like to plan a "Blossom Day", so a rough estimate of "peak blossom" is especially useful. Logging the actual blossoming time is also useful for estimating when the fruit might be ready to pick. While you are going round your trees and observing their progress, this is also a good time to check on their condition - do the stake ties need loosening? do they have any canker? any pest problems or general physiological issues?

So how do we do all this?

Firstly, we need to recognise the various stages of blossom development:

Bud swell

Some of the flower buds are just starting to swell

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Bud break

Many of the buds are starting to break out of their cases

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Mouse ear

The buds have broken and there are little leaf curls (see pic) on a good number of them

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Green cluster

The flower buds are evident in the centres of at least half of them, but are not yet showing pink

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Pink bud

Pink buds are evident on at least half of the clusters

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Full blossom
Blossom has unfurled on at least half of the clusters

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Petal fall
The petals are wilting and in many cases falling

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I have added pictures to each of the above as we go through this season (2025), so be patient if we are not there yet.
Points to note: at the bud swell/break stage, remember that we are looking for flower buds. These are fatter than leaf buds and usually break earlier. The blossom stage is often used by commercial growers, who spray chemicals on their apples, to determine the optimum (and least damaging?) time to spray. NCOGers prefer not to spray.

Geek point 🤓: If you keep a record each year (distinguishing between varieties) then you will be able to guess how long it will be until the blossom opens - assuming the weather conditions are similar. However, if the spring is warmer or colder than previously, things will happen quicker or slower.

Double geek point 🤓🤓: If you log the full blossom date for each variety each year and then the date when they are ready for picking, you can use this to estimate picking dates in following years. Again, this will vary depending on weather conditions so a warmer summer (or at least a sunnier one) will mean that picking can begin earlier.

Triple geek point 🤓🤓🤓: You can use an app on your phone to do all of this. If you need to ask how then you are not a real geek, just an apple geek 🧐