Sick Choisya ternata plants

[Madcat]

Hi community, I have a row of choisya ternata plants against my front fence that were planted by a landscaper. Unfortunately 3 went yellow and died, so I bought new ones and replaced them. Now 2 of the 3 replacements are going yellow too, but the neighbouring plants are growing well. Not sure what is causing this, so hoping some experienced gardeners out there could help ?

 

[EricL]

Hello @Madcat

Welcome to the Bunnings Workshop community. It's great to have you join us, and thank you for sharing your question about your Choisya Ternata plants.

There are a few things that might cause your Choisya to turn yellow. One of them is overwatering if the water beneath the soil is not draining away fast enough the overly damp soil is detrimental to its roots. Remove the stones near the root area and let the soil breath to allow evaporation to occur.

Next is soil imbalance, this particular area could be lacking in nutrients, I suggest digging out the soil and mixing in some Garden Basics 25L Organic Compost to improve soil condition. 

The third and final option is soil compaction. The soil in that area has hardened and becomes impossible for the roots of the Choisya to borrow through. I suggest digging deeper and loosening the soil to allow the plant roots to travel into the soil.

Let me tag our experienced members @Noelle and @Adam_W for their recommendations.

If you need further assistance, please let us know.

Eric

[Madcat]

Thank you very much for your response Eric ! I will certainly give this a go. I have weed mat there under the stones as well so that could be keeping it moist all the time. I'll try that and leave it for a few weeks and see if it improves

[Adam_W]

Hi @Madcat, I just checked one of my rather detailed plant reference books & a point they very much emphasised is that Choisya must have good drainage and if anything they will perform better in soil that is on the dry side.
Investigate to see if drainage is an issue in that particular spot. It may be there is clay in the soil there or it's a low point where water collects?

[Madcat]

Thanks @Adam_W ! I've moved away some of the pebbles and opened up the weed mat around the base. Hopefully that will help the soil dry out and breathe 

I have a moisture sensor at the base of that plant and it reads 19% moisture

[MitchellMc]

Keep us updated on your plant @Madcat and I hope you see improvement soon. Reach out if you need further assistance. We're here to help.

Mitchell

[Madcat]

Thanks @MitchellMc ! Will do !

[Madcat]

Update: I noticed recently that all of the other plants to the left of the one in the photo (about 4) have started going yellow and the one at the end of the row appears to have died (this was a replacement for the previous one that also died). (There is a very slight decline to the left of the one in the photos)

I used one of those analogue pH and moisture sensors and pushed them in all the way into the dirt (about 30cm) and at the base of the dying plant it shows "wet" and for the one in the photos, "moist", so it appears that @Adam_W 's suggestion may have been spot on (the probe rages are wet - moist - dry)

Not sure what to do so am seeing suggestions. I have stopped watering, but if it rains then the problem will continue. Should I replace the Choisya Ternata with different plants that like moisture & clay soil ? or is there a way to improve the drainage ?

[MitchellMc]

There are a number of Australian natives that will tolerate wet clay-based soils @Madcat. Plants like Callistemon citrinus and Melaleuca squarrosa come to mind. Alternatively, suppose you are going to replace all the plants. In that case, it might be an opportune time to remove some of the clay-based soil, replacing it with premium garden soil whilst installing draincoil to divert excess water away from the area.

Mitchell

[Madcat]

Thanks for the ideas @MitchellMc ! would you have any suggestions for hedge plants that tolerate wet clay-based soil ? (The ones you suggested appear to be large bottle brush trees so probably not suited up against the fence). The Choisya ternata's were meant to form a nice hedge against the fenceline however I could change it from a hedge to a row of small, nice trees

I'll give the soil a go too when I find a good plant replacement but I don't think I'll be able to install the draincoil due to where the decline is (meets the front concrete footpath)