from Granary Oils
Dates for the next 3 courses have been published on Eventbrite, as before we have funding from the Cotswold National Landscape (formerly AONB) for residents or those working within it.
If you are outside our AONB then you can still attend but contact me first please.
June 24th 2024, October 28th 2024 & 10th March 2025
One of the biggest dangers to walnuts is spring frost especially in our Northern European climate, cultivars can break bud from mid-March (very early) through to mid-May (very late) so it’s critical to select the cultivars appropriate to your microclimate. If you rarely have frosts after early March you’re very lucky and have an enormous choice, most of us don’t.
Spring frost damage takes place once buds have started to break and the bud scales have fallen off, any broken bud, leaf or flower will suffer with any kind of air frost, blacken and fall off. The good news is that walnuts will reshoot from a lower bud fairly easily.
The difficulty with selecting cultivars is that there is very little reliable information and often what there is has been plagiarised from countless other sources and almost all of it from other countries, so whilst it can be useful it is often not specific to our climate.
Cultivars can be advertised as very cold hardy, meaning in continental climates the trees ability to withstand winter cold temperatures without trunks splitting or dormant buds being damaged when dormant, it does not translate to spring frost resistance!
No Juglans will take spring frost to new foliage.
Below are photos of various Juglans and the damage (or lack of).
Seedling Heartnut – slight damage to a few leaves but generally unaffacted, most trees in the part of the orchard were completely unaffacted.
Grafted Butternut – No damage at all
Heartnut Jewelbox – The only other heartnut affected, a few leaves again but the flowers were not touched.
Walnut Perushtinski – Near the lower part of the orchard and one of the earliest into leaf, probably the most damage but nothing it won’t recover from, young leaves like this are the most vulnerable along with catkins.
Hican Marquardt – all the Carya cultivars and species seem to be less susceptible to mild frost, harder frost (below -1C?) will still damage them though.
Due to changes from Fedex/TNT on 1st March 2024 we can no longer ship larger trees, we are now limited to a maximum length of 1.2m before getting hit by a very large surchage.
In reality this means all the main crop bare-root trees will be collection only in the winter, the smaller bare-root specialist walnuts and pot grown Carya should still be transportable.
The very mild wet winter with no really cold frosts (-5C Lowest) has meant a much earlier bud break and flowering start, 10-14 days depending on cultivar. This is true of all the different walnut species (including the Carya) and pretty much every Heartnut has juvenile leaves already, we’re praying no frosts now but realistically we need to get to mid May here to relax. The very latest cultivars like Fernor have just started loosening their outer bud scales about a week early.
It’s too early to say what effect the wettest winter in maybe 100+ years will have apart from killing a few trees in marginal positions, a bit more blight possibly if we get a very dry summer again, which for us on our mostly acidic old pasture seems to be an issue in some parts of the orchard.
The 1st picture below is of the heavy male catkins developing on walnut Jupiter already, these will probably start dropping pollen in 2-3 weeks maximum, they won’t be the earliest but it is one of the heaviest and most reliable of our main crop pollinators, better than Broadview which seems more sensitive if there are any frosts around.
The second image is of walnut Sychrov’s female and male flowers, this is always the earliest to bud break and set pollen and unfortunately 4 out of 5 years gets frosted, of the main crop walnuts Saturn is probably the next which is why we took out 35 trees and only left 15.
