Last week I shared a post over on instagram of my Oxalis triangularis purple, in which I asked my readers if they had any care questions they’d like me to cover in this year’s annual Oxalis post, which has become a bit of a tradition here at HPH. And questions you certainly did have! So for this year’s post, I will share the obligatory update on how things are looking, plus my learnings from 12 months of growing this plant in a new climate. Alongside this, I’ll dig into your questions… so let’s begin.

Oxalis triangularis update + observations on growing in a new location…

If you read my recent small space gardening 2-part post (here + here), you’ll know that I only sifted through my 3 pots of Oxalis corms a couple of weeks ago. Partly because there’s been a lot going on here but mainly because it was still so cold! This time last year my pots were all showing signs of life + by mid June were bursting with colour. Things will be a little slower to start this year, but that’s okay — it’s been a completely different growing environment to navigate over the last 12 months or so. On that note, here are some of my thoughts on how my Oxalis have behaved in a new location…

1. Slow + steady is best

As much as we generally want our plants to grow into magnificent specimens, it’s better to start slow when your Oxalis shows signs of life after dormancy. In their previous home on my balcony garden in my old east-facing apartment, I was in charge of the watering + it meant I could regulate this easily. In an outdoor garden with no cover, this is a different story altogether! I can’t control the weather (shame) + I’ve really noticed how differently my Oxalis have reacted to this over the last year. This is something to be mindful of with your pots as they wake up because we have had so much rain in May, I think my pots in an exposed position would have got overwatered. If you can pop your Oxalis under a canopy like a doorstep or porch, or even a greenhouse if you have the luxury of one, your plants will thank you for it if you live somewhere where it rains a lot.

2. Provide shelter where you can

This was something I hadn’t fully considered when I used to moan that my balcony garden was in a pretty shaded spot! The balcony was on the second floor of a lovely old apartment block + semi-enclosed in a horseshoe shape. This meant that despite being really close to the sea, the plants weren’t exposed to the elements in the way they are now. Leading on from the first point above, Oxalis do prefer a more sheltered location I think, at least I think they grow better in this setting.

3. Overwinter in a protected spot or indoors

The Winter was pretty brutal here + it was slow to dissipate — as such, it felt like it went on for a few months too long! As the temperatures dropped, I huddled my Oxalis pots underneath my table + chairs which were covered with a tarpaulin + this provided a somewhat sheltered spot for them. But it was COLD so after a time, I opted to raise them up off ground level + moved them atop of the chairs to sit out the bleak December + January. In the new place, frosts + snow are a much more common occurrence than I’d ever experienced living at the seaside. So in this kind of environment, I think I’ll try to overwinter my plants in a porch area or somewhere more protected from the chilliest part of the year. We shall see how my pots fare this Spring + if their growth has been affected at all. I’ll keep you posted.

4. Raise the planter off the ground

It doesn’t have to be at any great height, but raising your plants up a bit can really help keep pesky bugs away! On the balcony, it was a rare sight to find anything eating my plants, unless something was lurking in a pot from the nursery (that’s why it’s always good to quarantine new plants!). This happened in my last Summer there with the arrival of a caterpillar that quite liked to munch the Oxalis. In a regular ground-level patio or garden though, there can be a riot of all sorts, particularly slugs, so using planters on a stand or a wall mounted option can help. Another reason to raise your pots off the ground is because in colder weather, it can help them to keep warmer than if they are sat directly on freezing ground. If you are in a colder location, it might be worth thinking about a more permanent solution, but even those little plant pot feet can alleviate this quite considerably.

5. Give the pots room to breathe

This is especially important when it comes to plants with lots of foliage like the Oxalis in somewhere with a proclivity for rain, or if you are watering using a hosepipe. It might sound bizarre if you are used to watering a garden, but I’ve only ever really watered with a can + directly into the top of the pot. My outdoor foliage plants on the balcony stayed pretty dry for the most part. Last Summer, one of my Oxalis planters fell foul to rust + it was very swiftly chopped right back! I’ve talked about this in more detail here FYI. But in short, a dense pot with lots of leaves coupled with changeable weather conditions + a lack of ventilation around the pots can be troublesome.

Your Oxalis questions answered…

Are they happy outside too? / Is this suited for outdoors as well?

Yes! I’ve grown it inside + out but on reflection, I prefer to grow mine outdoors. Over the last 2-3 years, Oxalis has been marketed quite a lot as a houseplant because of it’s lovely coloured foliage + interesting triangular leaves. But for many gardeners, Oxalis is primarily grown outdoors. If you are interested in moving yours outside too, you will want to acclimatise it over a few weeks if it’s only been used to indoors. Do this in the same way that you would harden off your seedlings outside for a few hours a day over a number of weeks. Also, try to keep it in a more sheltered location in a more shaded position too.

Here are my two indoor pots to the left, compared to my larger pot that lives outside:

I didn’t know that they flowered? / How do you get your plant to flower?

The flowers can come a little bit later in the growing season, especially on a younger plant. As the photos above show, I have found they will often produce lots more blooms when outdoors than when inside. Flowers will often appear when the plant has grown into its pot + is almost ready for a larger planter, but these plants don’t need frequent repotting at all. Repotting too often or in a pot that is too large will reduce the likelihood of flowering.

Oh no! I thought mine died completely! I didn’t know they go dormant! / I thought it was just another plant I managed to kill! / I think I would have thrown mine in the bin!

These remarks are just a small selection of words to that effect that all come under this ‘question’ which concerns dormancy. It’s quite a shock + can definitely make you panic + think you’ve killed your plant! I was amazed to see mine come back to life after the first winter I grew it so I completely relate to the many funny comments I got about this aspect of Oxalis care. I’ve not found it discussed much online, which is why I put together an Oxalis dormancy care post.

How many tubers do you have in this planter? I planted 5 in one pot + it doesn’t look full enough…

Ah that’s a good question! In the larger pot below I’d say there are about 25+ — the tubers mature + multiply over time + last year I started separating them into different pots as things got more crowded. In this blogpost there’s a photo of how multiple stems are attached to a single tuber (around half way through the post), so I generally just throw roughly the same amount across 3 pots, with some of the more mature ‘carrot-like’ corms in each pot. You’ll be surprised how much the tubers develop after a year or two!

How do you know when to repot?

Oxalis triangularis don’t require regular repotting + I don’t often need to repot mid-way through the season. My plant had such a boom in growth over 2019 that towards the end of Summer I was starting to notice new tubers popping up at soil level! You can see this in the photo below right. It was at this point that I decided to grow my collection on by dividing up the tubers before the 2020 growing season.

I never considered bringing mine outside! Now I’m wondering, what kind of light would it want outdoors?

Ah yes — well I actually dug this plant up quite a few years ago from a relatives garden after seeing the plant for sale in a pot outside the Liberty London store in 2017! I have grown mine best on a sheltered balcony out of direct light. In brighter light the leaf markings are more pronounced — they are a bit darker in a more ambient light position. As I mentioned earlier in the post, if you are thinking of transitioning your plant from indoors to outdoors, carry out the process gradually to acclimatise the plant over a few weeks. If in doubt, keep out of direct light + in a sheltered position if possible. You will probably find the pot will need more frequent watering outdoors + the stems might ‘faint’ if the potting mix gets too dry. But they are quite resilient really + will often bounce back after a thorough water.

Above shows my plant on the balcony in 2019 before I divided it up, Below, the 3 pots here at the cottage in Summer 2020.

My green one is getting sparse with no new growth… it’s down to 20 stems when it started and I bought with 40! / I bought mine with flowers but haven’t seen any since!

Hmmm that sounds like it could be a light issue (not enough or too bright) or a watering issue perhaps — it might be worth taking the plant out of the pot to make sure the tubers aren’t soggy or rotting. If it’s in a heavy soil that gets waterlogged this can happen. I add perlite into my potting mix. Another thing to consider is the container you have your Oxalis planted into — for me, I find terracotta dries out too easily + I’ll often get shrivelled up stems occurring in this type of pot. I’ve found a nursery pot to be the best, but I’ll use a terracotta as a cache pot or cover pot.

In terms of the flowering, that is frustrating! I wonder if you are growing it inside or outside? I find mine flowers more readily if I fertilise it twice a month + they also occur more as the pot matures — so later in the summer months is when there are the most blooms. As you will be able to compare with some photos earlier in the post, you’ll see that my indoor Oxalis rarely flowers, but my plants outside have an abundance of blooms!

o9

Mine just came back to life but tiny leaves, what could be the problem?

Growth can sometimes start off smaller, especially after dormancy — in the photo above right, you’ll see that my initial growth last spring was also very small as my Oxalis was waking up after its winter rest. These small leaves will often get taken over by larger foliage as the plant gets growing. Another HPH reader also confirmed this was the case with her plant too, so hang in there! I’ve also found that replanting the tubers in fresh potting mix annually at the start of the growing season to be a good way of keeping the plant as happy as it can be. It’s also a good idea to think about fertilising when active growth starts too as this can really help the plant stay strong + growing healthily.

Does this beauty need a lot of sun to grow like this? Or just grow under medium indoor light?

Thank you! Mine prefers an ambient light position — if it’s too sunny I find the blooms in particular (if there are any) fade more quickly. The foliage can also crisp up a bit or wither altogether if the location has too much intense light. Be aware that if growing indoors, you might notice a different growth habit to those pots that are outside. Slower + more steady growth will help keep your Oxalis happier for longer, so an indirect light position is best for longevity.

Mine is ‘alive’ all year round! It was my first year with this plant so I was confused when people warned me it would go dormant + it didn’t. I wonder if mine will still explode with spring growth…

Ahhh how lovely! I must say I’m a little envious… my climate is far too cold. Another HPH reader commented here too + said that they have also experienced a more steady stream of new shoots, as opposed to an explosion of new growth come Springtime. I know that some growers will try to trigger dormancy by reducing watering as the cooler part of the year approaches. Others will simply chop back all new growth + move somewhere darker + cool in wintertime, even if it’s not being grown in a very cold climate. The main thing to note here is that regular feeding when the plant is actively growing will help keep it looking its best + I always feed at half the recommended dilution rate. If your compost has slow release fertiliser in it, be sure you aren’t doubling up on fertiliser as this can cause some damage to the tubers.

o2

What do you do when half the plant goes dormant + the other half keeps growing over winter? It’s really dry over winter in my house so I have to water quite a lot, but I worry it’s too much for the dormant tubers.

Thanks for your question! I know what you mean — the dormant tubers might rot if they are getting too much water. I’ve tried two ways before with this — if I can separate the ‘alive’ part I will pot that in a separate pot + keep the dormant tubers apart. These days, now that my tubers have matured, I’ve got a bit more brutal with them + I’ll just cut the whole plant back when over 60% of it goes dormant! You can also do as I mentioned earlier in this post + try to provoke dormancy by moving the plant to a cooler, darker location if you want to encourage your plant to have a sleep. If part of your plant is becoming dormant, it’s usually only a matter of time before the other part of the plant will follow suit.

I repotted my oxalis today + it looks like I accidentally ripped the roots off my tuber! Do you think they will grow back? I just popped it back in the pot hoping there’s no real damage…

Ahhh that’s happened to me before too — they will grow back! But just be careful not to overwater so that the tuber doesn’t get too soggy if it’s damaged at all — they are quite resilient. When I take my tubers out of the planter like below, it’s inevitable that some minor damage will occur, despite trying to be gentle with the corms. After a few weeks, if temperatures allow you’ll often see new growth popping up. If your potting mix is very heavy, add in something to improve drainage + aeration such as perlite (that’s what the white speckles are in the two photos below in case you wondered!).

o11
o7

I have to say mine is a little spindly, no way near as vibrant or as full as yours is! Any tips to help it grow like yours would be greatly appreciated!

Thank you very much! My plant is a few years old now so I think I’ve figured out what it likes. Hopefully by reading this post, you’ll have gained a more in-depth understanding too! I’ve also added the links to my previous Oxalis posts below (at the end of this blogpost) for you to have a look at more specific elements of their care. If possible, I’d recommend making up a back-up plant in case one of the pots starts to struggle. They really are such pretty plants, particularly when they first appear, but they can often end up looking a little bedraggled + droopy or spindly later in the growing season.

If you want to read more about oxalis care in general, or to see how my plant has matured over the last few years I will link my posts here (they are clickable links!) :

So there we have it! I hope you’ve enjoyed reading some of the most commonly asked questions around Oxalis care + that it has offered some help + advice in growing these lovely plants. Whether you choose to grow these inside or outdoors, I wouldn’t be without this plant + it’s purple butterfly leaves! Happy growing + here are some pins to share or save with someone that might like this plant:

sign off

Posted by:Laura HPH

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