What to feed nandina

[evtubbergh]

I have a Nandina in a pot. It is in rich, well-drained soil and does not get a lot of water but it does get enough. It does not get enough sun though because I have a vigorous viburnum that keeps blocking out the sun. It shouldn't die though because of that surely?

I also did not cut it last winter, which I believe encourages new growth and I will remember this year.

It has leaves on all lower canes but the one tall cane has lost almost all it's leaves.

I have just fed it an organic 5-1-5 fertiliser as it is past mid-summer and as I understand it, new canes only really grow in spring while now it should be concentrating on fruiting and/or leaves. It used to do really well, in fact the large branch to the right was in front and it obviously grew quite a lot. It was originally planted with bone meal and 2-3-2.

What should I be feeding it and how often? Could the yellowing of the leaves be a lack of feeding or something else?

It does go a little red in winter but not as much as it could because the tree also protects the garden from frost.

Oh and in addition I did not get flowers this spring, so as you can see, no fruit. I don't mind if that's just because of the lack of sunshine but I do want it to be healthy otherwise.

[rainbowgardener]

The yellowing of the leaves, with the veins remaining green is called chlorosis. It is usually a mineral deficiency in the plant, often iron or manganese. HOWEVER, that may or may not mean the soil is deficient. Anything that prevents the uptake of these trace nutrients can cause it, even when the soil is not deficient.

That would include anything that damages the roots and their ability to uptake nutrients, like soil compaction. If the soil is very acid (like less than pH 5) or even a little bit alkaline (like 7.5 and up), it can tie up the minerals in the soil. If the roots are staying very wet or in severe drought conditions, it can cause chlorosis. So you need to know what is going on with your plants and which of these conditions might apply.

[evtubbergh]

Thanks. I will try to figure it out. It is defintely not very wet. It has dry periods because that is what Nandina likes but never to the point of absolute drought for days on end.

I have fed this plant within the last 8 weeks though and since the soil is fine otherwise I would go with PH.

I did try to order a PH meter once but the order just wouldn't go through. If I get one then great otherwise I will have to figure out another plan. Is it more likely low or high PH? Maybe high PH? It would be easy to rectify either but not so easy to figure out which one.

[rainbowgardener]

High pH would be more likely to cause it, but if that is potting soil with peat moss, it isn't likely to be alkaline. Peat moss is acid.

[evtubbergh]

No, no peat moss. But now I can't remember if I used acid soil when I planted it because Nandina does not like alkaline soil. Sigh! What a pain. This might actually be the problem. I will figure it out and remedy it. Thanks.

So this would affect the growth of the plant and cause it to lose leaves?

[rainbowgardener]

Yes.

The leaves are pale/ yellowish because they lost their chlorophyll. Chlorphyll is how the plants trap energy from the sun and make carbohydrates. Without it, they can't grow and eventually can die. Your plant obviously still has chlorophyll, just reduced amounts, so it isn't going to die, but can be stunted, and the worst affected leaves will fall off.

[applestar]

Have you checked for sucking pests like Spidermites or scale?

I'm not up to verifying right now, but when my mom gave me a volunteer Nandina, I remember choosing a sunny location and putting a lot of sand in the area where the subsoil is clay to plant it. I remember I chose this area because it tends to avoid the summer drought, being downslope from my little rice paddy. So well drained moisture rich soil?

[ElizabethB]

Rainbow is correct - it does look like chlorosis. Since the older leaves are being affected that would be a magnesiam/zinc deficiency. When new growth is affected it is an iron deficiency. As she pointed out I would check the pH before adding amendments. The soil pH meters do give very accurate readings. The paper strip and tablet kits do not. Try calling your local nurseries and garden supply stores for a meter. The big box stores sometimes carry them but not until later in the spring. If all else fails try ordering from a different source. Pruning nandina is not a top pruning. When canes get too tall or lose their bottom leaves remove the cane from the base. Don't chop off the tops. You may also want to consider a larger pot. Nandina spreads. Gently remove the plant from the pot and check the roots. If they are wrapped around the root ball you definitley need to pot it up. Gently loosen the roots first.

Good luck

[purpleinopp]

The more you cut it down, the more it will grow. Tall canes will be naked at the bottom, that's just their nature. I think an individual cane needs some age to make flowers, so you might want to leave the tall one uncut and see if it will flower. My Mom has these in pretty heavy shade and they flower, so I don't think lack of sun is your issue unless there is no direct sun on it at all. A hour or 2 should be enough.

[evtubbergh]

Thanks everyone. My nandina is much better. It actually grew some new foliage which is much darker and I am sure in spring it will really come back. I hope it flowers this time

[evtubbergh]

Aargh, here is the image: