It is easier to maintain specific plant collections when you have a nursery. In that situation, special plants are maintained under nursery conditions and given more individual attention and care than in general garden collections. We used to carry a large array of different bulbs when we were doing mailorder and they were repotted on an annual basis, or at least every two years. We only listed bulbs if we had enough stock reserved to keep going for the following years.

We put out our last mailorder catalogue in 2003 – twenty years ago – even though I still get email and phone requests from people wanting to order plants from us! In the years since, I have planted most of the good bulbs in the garden, scrapped some that may have been botanical curiosities to half a dozen afficionados throughout the country but were of little merit as garden plants and the rest have languished under a regime best described as benign neglect. Some have not survived this laissez faire approach but, with an extra pair of hands, we are starting to salvage what has.

Our gardener, Zach, is doing his apprenticeship and one of his modules is on plant collections. I suggested the ornamental oxalis as a well-defined collection he could assemble in one place. There is no doubt that most of these thrive and look their best in containers. I have never forgotten Terry Hatch’s magnificent display of oxalis in pots at Joy Plants and that must be 30 years ago.

For years, I maintained a collection of my favourite oxalis in pots to be brought out when they look their best in autumn and early winter. I hate plastic pots in the garden so they were all in terracotta, ceramic or vintage concrete pots and truly, I just got fed up carting these heavy pots out of the nursery and into the garden and then back again when they were over, not to mention the annual repotting. I gave up and planted them out and let them fend for themselves. The most invasive of them, I put in shallow pots and sank the pot in the garden, but I rarely repotted them.

Zach has so far isolated 23 different forms of ornamental oxalis that grow from bulbs. Most are from the garden here and a few he has added from his own stash of plants at homes. (Note: he has just sourced another five from a local market, he tells me.) Amazingly, I think we only lost two varieties in the years between my getting them out of the nursery and him getting them back in again and they weren’t a great loss. I suggested that he also pot up the weedy ones we battle all the time. The creeping oxalis – O. corniculata – which we have in bronze and green is the worst and we have a pink one in a patch of grass that may be O. corymbosa.

Then there are the more herbaceous oxalis. The best known of these is probably what we call a yam in Aotearoa New Zealand, although technically it is growing from a tuber. Commonly known as oca in Spanish, it is a food crop and one we grow ourselves, semi naturalised in the vegetable garden. Botanically it is Oxalis tuberosa.

We have Oxalis peduncularis growing in one of those awkward, narrow borders against the house and it looks and grows more like a succulent, flowering for most of the year. Now that I am getting my eye in again, I have spotted another plant that is like a dwarf peduncularis but I have never even thought about what it is because it has just always been there, in its place. It must be another oxalis.

The family is huge overall with somewhere over 550  different species in the wild across most of the world except the polar areas. I have only just discovered that we have a native one – Oxalis exilis. It is a small creeping one and I think it is probably one that I assumed was corniculata, too.   

The thing about plants is that the more you learn about them, the more interesting they get. There are many worse rabbit holes in life that one can go down than the intricacies of the oxalis genus. I can see that Zach’s oxalis collection will probably continue and expand long after he has fulfilled the requirements for his level 4 apprenticeship.

I am wondering now whether I can get him onto isolating and sorting the intricacies of the lachenalia collection next. That went pretty much the same way as the oxalis collection when we retired from mailorder but is more complicated because of their readiness to cross with each other and produce natural hybrids. He doesn’t need to do it for his apprenticeship but I think he would find it very interesting and it would be satisfying to sort it out again. At least all the lachenalias are bulbs and there are only about 133 species so that makes it more tightly defined.