AusBonsai

I planted a load of grevillea seed last spring and had a fairly good germination rate, a first for me & Grevillea. All up I got about 15 seedlings come up.
Wanting to start them off on the right track from the start, as soon as they were big enough to handle I removed them from the seedling tray, cut the tap root, leaving what fine feeders they had and potted on into individual 4" pots. Over the course of summer I lost one after another until I had just 1 left.

I repotted this one into an 8" pot as it had filled the 4" with roots. It has continued to grow but has never been very healthy looking even when in the 4" pot. I am starting wonder if I am doing something wrong with it. I have used osmocote native fertililzer and have it my regular 50/50 mix of gravel and potting mix. I have attached a pic to see if any can help with what might be the problem and provide some advice on what else I can do. Being a seed grown plant there is a slight chance that the colour is normal but given its slow growth rate compared to what I am used to with this species. And also the fact that some leaves have a more normal colouring to them there has to be something else going on. HELP!!! It is not a cost issue as it cost me nothing but time & a bit of soil/fert, I hate losing any plant if I can avoid it.

Matt

Edit: forgot the pic

Did you use 50% native potting mix? I think Grevillea leaves turn yellow before they die with too much phosphorus.

Or they might need a pinch of iron chelates.

Google Gavelia yellow leaves and you get similar suggestions as Craigs iron chelates as well as possible pH issue offcourse.
This sounded informative.

However, mixing a packet of Magnesium sulphate(Epsom's salts) in approx 20 litres of water and applying it to the soil around the plant(making sure it soaks in around the plant), will help the plant to unlock. Mixing iron sulphate or chelated iron in with the above will help with the yellowing leaves. However this may have to be repeated a few times to have any noticeable effect. Regularly watering the leaves with a very light soluble fertiliser mix(including some iron or zinc sulphates) will also help. I have used very weakly mixed Nitrosol(Aquasol) and iron sulphate solution watered or sprayed onto leaves on a weekly basis to resolve these problems. Most native plants prefer fertilisers to be applied to the leaves. Almost all fertilisers are acceptable to natives despite all tales to the contrary. The trick is more to use them lightly(mixed with a lot of water) and frequently.

Other possible causes include fungus disease from soil borne fungi. This may not be repairable and the best solution is to avoid certain species.

Several sites state the possibility of Phytophthora. From what I read I reckon it would kill seedlings pretty quickly so not sure yours whould have gotten this far with it? but it is nasty (kills all, no treatment) so better of to be prudent and not let the water run of get to any other plants as it travels in the water soil to soil.

The first visual symptoms of infection are generally shown as yellowing of the foliage (chlorosis) followed by dieback of the entire plant. Depending on local site and environmental conditions, this can occur in a matter of weeks for small shrubs or even several years for large shrubs or trees.

http://www.environment.sa.gov.au/biodiv ... ooklet.pdf