yellowing of new growth

15 years ago

The emerging leaves and shoots on several of my salvias as well as two annual hibiscus and a lemon balm are quite pale. It seems to be almost random too. S madrensis,"Red Dragon" and one of the two S.nemorosa in one garden bed are affected while two S. greggii are untouched. "Costa Rican Blue" has yellow tips while its bed-brothers S. canariensis and "Black and Blue do not. The affected S. wagneriana is next to untouched S. guarantica and another S. greggi.

We don't have frost. Each bed was given the same feedings and mulchings. I can see no parasites. All of them are in pretty much full sun (except the S. wagneriana) and all would have a certain amount of competition from tree roots as it's been a very long hot summer. All of them get a feed of fish emulsion and/or seaweed every month.

Any ideas??

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Comments (5)

hybridsage
15 years ago
ladyhana:
Do you see green veins in the yellow leaves? What is your
soil ph?The other problem could be a nitrogen deficiency as well.
I am not familiar with the soil types in Australia
so please help educate me.
Sicerely
Art
rich_dufresne
15 years ago
I had a number of my stock plants develop yellow leaves because of a cold spell just after the plants broke dormancy. Now that the weather has turned warmer again, they have resumed growing. The yellowing could be a problem with the roots. Too much cold and wet will do that.

As Art said, pH can also be a problem, resulting in reduced uptake of certain micronutrients like iron. Microflora and microfauna population changes might also be affected.
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ladyhana
Original Author
14 years ago
The soil here is originally Bay of Biscay; a slightly alkaline, heavy clay. I have been improving it by raising the garden beds and adding large amounts of organic matter over a period of years. It is currently mulched with about 5cm (2") of composted rabbit bedding, so there is a fairly high nitrogen level.
We had a very hot, dry Summer followed by an extended warm spell through Autumn with daytime temperatures around 25 - 30C (75 - 85F). The first significant rain since September arrived with Easter, along with a 10 degree drop in temperature. This means the daytime is about 18C (65F) and the nights have got down to about 9C (48F).
There is no yellow veining. The ones I listed are just beginning to flower, all are less than twelve months old, planted at the end of last Winter. It is likely that they have not yet acclimatised, and the sudden temperature drop is at issue here. The days will get steadily cooler and wetter here for the next month or two.. I will see what happens next.
hybridsage
14 years ago
Look at giving your plants some nitrogen that should help them green up with (a iron and some sulfur content as well). We have alkaline soil here also. The phosphorus levels may be out of balance causing the yellowing(to high).Rich
has a excellent point that it may just be the colder weather.Wait until next spring and see if the problem persist.
Art
Art
andy_sa
14 years ago
I had a similar problem in a relatively new garden-sandy loam, great for planting, but salvias and abutilons experienced yellowing while still growing bushy. Charlie Carp soon sorted it out!