Asparagus Season - Early?

It will soon be time to start enjoying our home-grown asparagus. The first spear of 2025 appeared on the 30th March ...

Photo 1: Early Start to the Asparagus Season 2025 (photo taken March 31st)

This is the second earliest appearance of the first spear coming just five days later than last year's (2024) record. The table below collates the 'date of first appearance' for the last six years.

Year	Date of First Spear (Day of the Year)
2020	2nd April (93)
2021	31st March (90)
2022	14th April (114)
2023	10th April (110)
2024	25th March (85)
2025	30th March (89)

In a previous post, I looked at a couple of weather parameters (Jan - Mar average temperatures and solar radiation) but could not find an obvious relationship with the first appearance date of an asparagus spear. A plot of total solar radiation in March against the day of the year when the first spear appeared is shown in Figure 1. Solar radiation can be used as a proxy for sunshine hours.

Figure 1: Relationship between Sunshine Hours and the First Appearance Date

Based on all six data points, there may be a weak correlation (R² = 0.25) between Solar Radiation and the first appearance of an asparagus spear. While correlation does not mean causation, I offer a possible explanation of the relationship in Figure 1. Higher solar radiation increases soil temperature and encourages early emergence of the asparagus. In support of my hypothesis, the correlation is much stronger (R² = 0.68) if we ignore the 2024 result. What was special about 2024? Apart from being the warmest year globally, you mean! Well the winter of 2023/2024 was the second warmest on record for England and Wales while Spring 2024 was the warmest on record (in part because May 2024 was very warm). With all that extra atmospheric heat around, soil temperatures would be much higher than normal and the beneficial influence of lots of sunshine would be less important.

Of course, it might be more complicated than that ...