How to diagnose issues with Teddy bear magnolias?

[SteveP4]

I have five planted in a row against a back fence in a raised bed. The centre three are the worst losing foliage. There is obvious stress, but how do I check if over or under watered? 

[JacobZ]

Hi @SteveP4,

Welcome to the Bunnings Workshop community, it is wonderful to have you with us.

Is it possible to get some photos from a bit closer in? Particularly of the leaves and the soil around those three central trees. Are the dropped leaves in the garden bed? Are they crisp or moist? Do the leaves at the top of the trees feel crisp?

I note the pattern of leaf drop, with the higher up branches looking bare compared to those that are lower down. Overwatered plants often lose older, lower leaves first and may have soft, limp new growth. Underwatered ones tend to drop newer, higher-up leaves first, with wilting that improves slightly after watering. 

Considering the elevated nature of the garden bed, it seems like the issue might be that water is draining outwards away from those central plants, leaving them underwatered compared to the other areas.

You could confirm this by using a Brunnings 3 in 1 Soil Meter in different locations around the garden bed, noting the differences in soil moisture.

If you find that the centre of the bed is not holding moisture as well as the outside, consider mixing in compost or manure, which will help hold moisture in the soil. Adding a wetting agent can also help water penetrate rather than run off. Finish with a thick layer of bark mulch to slow evaporation, but keep it a few centimetres away from the trunks to prevent rot. 

Over time, these steps will help balance moisture levels so the central trees receive a steadier supply of water.

If you do not find the centre is drier than the outside, report back and we can look at other potential causes and other solutions.

Jacob

[SteveP4]

Thanks Jacob.

Hard to see from the original picture I sent I guess, is the bamboo behind the fence, neighbour side. It drops a lot of leaves..

Also, there is irrigation running along the wall and trees, (watering daily) and since the picture was taken,  I removed a lot of the fallen leaves at the base of the trees. 

I thought, the soil beneath was damp and made worse by the bamboo leaves trapping the moisture acting as mulch.

It's hard to determine (from inspection of leaves at top or bottom) which are crispy or not.

I'm erring on the side of these trees being Overwatered right now.

With leaves cleared, I'm watering in seasol every two weeks and will see how it goes.  

Im attaching a close up picture of the middle tree, and a picture of growth I noticed on it, (which may mean nothing).

As I'm going to buy the moisture testing kit..   What reading is a good moisture level for these trees (so I know to regulate the watering regime?)

 

 

[JacobZ]

Hi @SteveP4,

I don't think you really need to test the moisture of the soil based on the fact that you are currently watering it every day. The truth is, this is almost certainly too much water. I would be reducing this to a deep watering once or twice a week for 15-20 minutes and using your finger to check the top 5-10cm of soil for dampness before watering again. If the top of the soil is still damp, it means the soil further down is still damp, and there is no reason to top it up. 

Watering every day keeps the soil constantly wet, which can suffocate the roots and lead to root rot or stress. Watering less frequently allows the soil to partially dry out from top to bottom, helping the roots get enough oxygen and encouraging deeper, healthier growth.

At this point, I would continue the applications of Seasol fortnightly, and just reduce the watering frequency to once or twice a week. The growth you are seeing is a good sign and an indication that things are improving.

If there is a lot of leaf buildup around the base of the tree, you should also rake it back as this can reduce the amount of oxygen getting to the roots. A 10cm diameter around the base of the tree is about ideal.

Let me know what you think and if you have further questions, please don't hesitate to ask.

Jacob

[SteveP4]

Thanks Jacob.

Ok, watering is off, and I'll assess moisture every week for now before manually watering.

I'll let you know how it goes... Hopefully I can post another picture of lush, green teddy bear magnolia trees here soon !