What are the white balls growing on my Chain of Hearts?
That random white ball growing along your Chain of Hearts stem or in the soil is not a seed pod, disease, bug or fungus. It's a tuber. And it's good sign! Chain of Hearts, also called Rosary Vine, is properly known as Ceropegia woodii. Here's more about what those white balls are, what they do, and how to make the most of them if you're lucky enough to get tubers on your Chain of Hearts...
What is the ball on my Chain of Hearts?
That white bumpy ball on your Chain of Hearts plant is a tuber, or aerial tuber, sometimes called a tubercle or bulbil. Most often first noticed along the stem (they're hard to miss), but you can also find them in the soil, usually in clusters, and they can get pretty big too. They normally start off round and have a cracked, dry appearance, but can change shape as they get larger. Tubers are more common to find in older, more mature Chain of Hearts.
Why do Chain of Hearts produce tubers?
The tuber-like nodes are not only normal but a good sign. Your Chain of Hearts is making the most of the good conditions and planning for a rainy day. Or rather, a dry day! The tuber is like a stash of emergency rations for your plant. They provide back-up storage of vital nutrients like moisture and sugars. They allow your plant to withstand long dry patches or times when conditions are less than ideal.
The reason tubers are considered a sign of a healthy Chain of Hearts is because your plant's got enough available nutrients to put towards forming a tuber, instead of using everything to fuel growth of foliage or flowers. I'd take that as a pat on the back for good plant parenting. Well done you!
Find out below what to do with your tubers...
Above: Tubers tend to start out round in shape but can change shape as they get bigger and older
Above: A mature Chain of Hearts with lots of stem tubers (copyright Lukasz Emski)
Above: Tubers also form at the base (copyright Becky Bec)
How to propagate Chain of Hearts from a tuber
Tubers root very easily. One of their jobs is to take root where they touch the soil, helping the plant spread and survive. Chain of Hearts are also relatively easy to propagate from a stem (look up the butterfly method if you're wanting to do it that way). But if you're lucky enough to have a tuber, you're pretty much guaranteed successful propagation. Tubers are an almost fool-proof way to either propagate and make a new plant, or fill in bald patches on your existing plant.
There are 3 main ways to plant a tuber. You can trim the tuber off the mother plant, or leave it attached, or a combo of both, where you start rooting it while it's attached to the mother plant, then trim it later once rooted.
My preferred way is keep the tuber attached to the mother plant, press it into the soil in a pot placed next to the mother plant, then once rooted, trim the stem and voila, new plant! You can also simply press and pin down the tuber into a bald patch in the pot of the mother plant to fill in the gaps and create a fuller plant. I find soil pins superb for that.
If trimming BEFORE you propagate, cut just under the tuber on one end where the stem comes out of the tuber, and keep some stem and a couple of leaves attached on the other end. I plant it so roughly half the tuber is in the soil, and the other half above the ground, with the stem end above ground. In a drier substrate press it down so it's about 3/4 below the surface.
How long does it take for a Chain of Hearts tuber to root?
They have a very high rate of success, but do take a while. I find Chain of Hearts tubers need a good 6 to 8 weeks on average for the tuber to root in good conditions (longer in winter, faster in summer). If you gently pull on the tuber after a few weeks you should feel some resistance which tells you roots have started growing.
Above: Plate 7704 of Curtis's Botanical Magazine vol 126 (1900) showing Ceropegia woodii Schltr (source), including tubers and flowers.
What substrate is best to propagate a Chain of Hearts tuber in?
I find it best to keep the substrate lightly moist when propagating a Chain of Hearts tuber, rather than let it dry out as much as you normally would for a mature Chain of Hearts plant. That's why the usual substrate you might use for an established Chain of Hearts tends to hold too little water for propagating a tuber.
I still use an airy mix but aim for medium instead of low water retention. I've found succulent mix with a little extra soil added works well. I use around 3/4 succulent mix with 1/4 soil or peat mixed through. I've also been experimenting with the pre-mixed Bio Leaf Starter Mix with great results so far (but again, just keep it lightly moist, not sopping wet).
Do you need to fertilise a tuber when propagating?
Yes and no. Until it starts producing roots I personally skip the fertiliser. The tuber has a store of nutrients built in to kickstart that root growth. However, once it starts to grow roots, then yes, I do fertilise. There are lots of options - and you can just use your normal fertiliser if it's not too high in salt (newly formed roots tend to be more sensitive to fertiliser burn from the high salt level of most fertilisers). My go-to is a specialist root fertiliser made for propagation, called GT CCS, which is low-salt and gentle enough to be safe for those sensitive new roots.