How to revive Mandevilla losing leaves?

[Rosana1]

Hello Bunnings workshop!

I bought a red Mandevilla from you guys a while ago and replanted it in our back yard, in a bigger pot. The spot is half shade/half sun, gets a bit of wind, but I believe it is a good place for it to grow and climb.

Unfortunately, the weather hasn't been very summery here in Adelaide, so it had to cope with a lot of rain, wind and some cold days so far, but also some sunny warm ones, so I'm not sure what's going on. It has many, many flowers, but recently it's been losing so many leaves. They all go yellowish before falling.It has increased a lot lately and they follow so quickly. It is also looking a bit sad, at least some parts of it. There's new growth , so I was wondering if the loss of leaves is normal due to all the flowers or if it has to do with the way we re arranged its branches with new supports and wall climbing devices. I'm attaching photos to give you a better idea. I have a water measurer stick that helps me water it only when necessary, so I don't believe it's water related.

Please help, a beautiful important piece in our backyard, would hate to see it die...

Thank you,

Regards,

Rosana

 

[JacobZ]

Hi @Rosana1,

Your Mandevilla actually looks very healthy, and the leaf drop you are seeing appears to be quite minimal. Mandevillas often shed a few older leaves as part of their normal growth cycle, especially when they are putting energy into flowering. Because yours is producing many blooms and new shoots, it is completely expected that some of the older foliage will yellow and fall away. This is the plant’s natural way of reallocating energy and keeping itself in balance.

The recent weather in Adelaide may still have played a small role, but only in a mild way. Cool nights, wind, and the extra rain can cause a few leaves to yellow, but in a plant that is otherwise thriving, this is not a concern. Since you have already given it a good position with a mix of sun and shade, and you are attentive with watering, the plant is clearly coping well overall. The fact that new growth is appearing strongly suggests that the Mandevilla is happy and establishing itself nicely in its new pot and support system.

Rearranging the vines and adding climbing supports can sometimes lead to a small amount of leaf loss, simply because the plant adjusts to the change. This is temporary and normal. As long as the stems are not pulled too tightly and have room to move, the plant will continue to climb and fill out beautifully.

For now, the best approach is simply to maintain your current care. Keep the soil free-draining, water only when needed, and provide light feeding during the warmer months. With the healthy new growth you are already seeing, your Mandevilla is on the right track and should continue to flourish as the weather becomes more consistently warm.

If anything changes or becomes more concerning, please get back in touch, but at this point, I don't see anything particularly concerning.

Jacob

[Rosana1]

Thank you, Jacob. I did think the photos would not show it all, as I had cleaned most of the yellow leaves, but I'll follow your advice and keep an eye on it. It is such a beautiful plant!

Have a great week, and thanks for the advice.

Regards,

Rosana

[JacobZ]

Hi @Rosana1,

The main thing that makes me think it will be fine is the new shoots. When plants are struggling, they divert energy away from new growth, so the fact you are seeing new shoots, even with the leaf drop, tells me that your Mandevilla isn't really struggling too much.

Keep an eye on it, but I think it will be fine.

Jacob

[Rosana1]

Hi Jacob,

It's me again! I've been keeping an eye on my beautiful Mandeville and each day I notice more leaves on the ground, on the pot and others turning yellow. Flowers are going dry, which I know happens, but what I've noticed is that even new leaves stop growing and turn yellow. I've been sweeping the floor and getting rid of the leaves and flowers that are already almost gone.This plant had a huge burst of flowering, it was looking gorgeous, so my doubt/hope, is that it is now exhausted but it will eventually recover. But I'm not sure, so thought of touching base: should I feed it with some organic fertiliser to see if this helps? Should I get rid of the supports I stuck in the pot to help it climb? I'm attaching more photos, you might be able to compare to previous images.

Hope you can help,

Kind regards,

Rosana

[EricL]

Hello @Rosana1 

Your photos show that your Mandevilla is going through a mix of post-flowering fatigue and temporary stress, which is very common after a big bloom cycle. The yellowing leaves and the amount of leaf drop suggest that the plant has been under a bit of pressure, especially since some of the fallen leaves appear to be newer growth that stopped developing. When the soil becomes slightly compacted, as it looks in the pot, the roots receive less oxygen, and this affects nutrient uptake. 

The combination of yellow older leaves, yellow new leaves and dropped bud's points to watering inconsistency or mild overwatering or underwatering. There is also a small possibility of early spider mites since a bit of speckling is visible, and these pests tend to settle in dry, warm spots. The good news is that none of this looks serious or permanent, and the plant appears quite capable of recovering.

Mandevillas often bloom heavily and then enter a natural resting phase, during which they drop more leaves than usual and slow their growth. After such a big flush of flowers, they rely on steady moisture, good root aeration and enough nutrients to rebuild energy. If any of these are slightly off, it can lead to the kind of leaf drop you're seeing. This doesn’t mean the plant is declining for good, only that it needs a bit of support to steady itself.

To help it bounce back, start by making watering more consistent. Allow the top two to three centimetres of soil to dry before watering again, and avoid leaving the soil soggy. A light, balanced fertiliser is a good idea at this stage Richgro 5kg All Purpose Complete Garden Fertiliser. A liquid feed made for flowering plants is also ideal Scotts Osmocote 1L Pour+Feed Indoor Plants, and organic fertilisers work well as long as they include nitrogen, phosphorus and potassium. Improving soil aeration will also help. Gently poke a few small holes in the top layer of soil with a chopstick to allow more oxygen to reach the roots.

There’s no need to remove the support stakes, as they aren’t harming the plant and simply provide structure. Continue removing spent leaves and flowers to keep things tidy and encourage airflow. It’s also worth checking the underside of a few leaves for tiny dots or fine webbing, which would indicate mites. If you find any, a weekly spray of horticultural or neem oil for a couple of weeks will manage it.

With these adjustments, most Mandevillas recover within a few weeks. The stems in your photos still look healthy and strong, so you can expect the plant to stabilise and produce fresh new growth soon.

If you need further assistance, please let us know.

Eric