Deciduous or not? October 2025 update.

Losing leaves and frost hardiness

Trifoliate orange (Citrus trifoliata, syn. Poncirus trifoliata or simply – poncirus) is probably the only truely deciduous citrus species. Dropping the leaves in autumn helps it survive the winter (it reduces water loss during frost). The trait is common within the species, though not to the same degree in every plant.

The case complicates with poncirus hybrids. Some are highly evergreen, others tend to drop a part of their leaves for the winter. Very few simple F1 crosses of poncirus and other citrus are fully deciduous. Losing all leaves is more common in complex hybrids with the predominance of trifoliate genes.

I think that while hardy evergreen citrus are desired for ornamental value, in very cold areas they need protection to thrive. A deciduous plant would be less susceptible to physiological drought when a prolonged frost occurs. There are of course more factors affecting hardiness, but I find deciduousness, along with proper dormancy, essential for zone 6 growing without protection.

So: which citrus plants that I grow in the ground are deciduous?

Poncirus

All mature poncirus growing here tend to change color and lose leaves for the winter. The most deciduous ones in my garden seem to be two plants that I once got as seeds from Karel Mundl. I thought previously that this is ‘Sladká’ strain, but now I suppose it may be a different one. Maybe testing the fruit will bring the answer.

The next in terms of deciduousness is Flying dragon. What’s interesting – its fruits ripen faster than on the one from Karel Mundl. So it seems that the two traits: deciduousness and ripening time – are not related, at least not directly.

The next are Kinga plants (either pure trifoliate, or a kind of distant hybrid – but I include it in poncirus). It’s normal that the shoots emerging in summer tend to keep their leaves longer – and that will probably be the case here. The plants may also become more deciduous as they grow bigger.

Probably the least deciduous trifoliate in my garden is the one I once bought from Łukasz, also known as LuckyJimi. It was originally used as a rootstock. In previous years, this poncirus tended to keep a few leaves for the winter, until stronger frosts destroyed them. This year it drops leaves much more readily. It seems to be a rule that deciduous tendency improves with age, or rather with the size of the plant.

HRS899 O/Q seedlings

The contrast is still visible between the poncirus-type, and hybrid-type plants. You can read more about them in the previous post. All are of hybrid origin, but the first group seems to have the predominance of poncirus genes; while in the second group the poncirus influence is less than 50%.

I don’t expect the second group to be fully hardy here – they are grown for experimental and breeding purposes, and survive with protection.

All poncirus-type seedlings have entered dormancy and tend to be deciduous, however with some differences in the time of dropping the leaves.
Out of the hybrid-type seedlings growing in ground, Sorfo has stopped growth but with only a very few leaves dropping, the rest are green; Korela still has new growth with no leaf drop. It’s also worth noting that potted specimens tend to shed some leaves, but generally I would consider Sorfo and Korela mostly evergreen.

An interesting thing – Sorfo has produced an odd twig with narrow leaves and shortened thorns.

Flying dragon hybrids

Two plants which emerged from trifoliate orange seeds – but are clearly hybrids – are Orla and Yolar. Both originate from Flying dragon, but only Orla is twisted. Pollen parent may be yuzu, citrangequat 4 seasons, or citrange Morton. As for Yolar, judging by leaf scent, I’m convinced it’s a yuzu hybrid.

Both plants show some deciduous tendency. I’m curious what part of the leaves will ultimately drop this year.

Yuzu, Hybrid from Schleipfer, Citrandarin FA-5

This multivariety grafted plant has been sitting in ground since last autumn. I grow it with some winter protection, mostly for experimental purposes.
Single leaves of yuzu turn yellow, the rest are green. I think yuzu has some predispositions to shed leaves for the winter, or during the winter, but it may be a different mechanism than in poncirus.
Scheipfer hybrid – this one is rather evergreen, and won’t drop leaves unless a stronger frost kills them, but despite that it proved very hardy last winter. Some yellowing is visible, but no signs of true deciduousness.
A single leaf from previous season has turned yellow on Forner-Alcaide-5; the current season leaves have not. It has some partial deciduous tendency. Interesting that despite of that, it’s not supposed to be very hardy.

The whole plant hasn’t grown much this year and may have some root issues – which can also lead to leaf yellowing.

Ichang papeda

Ichang papeda ‘IVIA F2’ has regenerated well after the winter damage. The problem with growing Ichang papeda in my climate may be that this species doesn’t develop proper dormancy. A warm period during the winter may kill it. In spite of that, I’m going to test its hardiness with some protection again. No signs of deciduousness and it’s not expected in this species, as it’s evergreen.

Evergreen or deciduous?

It’s rather expected that poncirus, and plants resembling it in appearance, will be deciduous. Not all will shed their leaves in the same time though. This may be due to genetic factors on the one hand, with plant size or age and environmental conditions on the other.

Even more interesting from my point of view are hybrids with adequate deciduous tendency, some of which may prove better suited to growing in my climate. I think that although there exist many hardy and mostly evergreen citrus varieties, for growing in very cold areas it’s better to choose deciduous or semi-deciduous plants, and the ones which are able to enter deep dormancy. It’s also worth to further study the relationship of deciduousness to overall frost hardiness.