Bamboo leaves are yellowish

[TexasGrower]

I've noticed that a select few have yellow leaves. My guess is over watering (it wont stop raining in Dallas). Thoughts?


Update 9/2/07... I took some photos.

http://s181.photobucket.com/albums/x293/joebannon/Bamboo%201/

[Mark Meckes]

Whew. I know what you mean by too much water. An unusually rainy season it's been for parts of Texas.
Container plants can especially be prone to getting 'warshed out' from too much water.
Another factor leading to chlorosis and yellowing bamboo leaves is the soil PH.
Most bamboo species prefer soil on the acidic side and are sometimes not able to easily take up nutrients essential to healthy green leaves if the soild it too alkaline.

Here's a well written article that discusses yellowing leaves, and though it is about Roses, they too often grow better in more acidic soils, so much of this can apply to bamboo.
In fact I have used 'rose' fertilizer for my potted bamboo at times.

Yellow Leaves on My Roses
http://www.gardenguides.com/how-to/tipstechniques/flowers/roses/yellowleaves2.asp

This article discusses soil PH and outlines ways to amend the soil's acidity or alkalinity to make it more suited to growing bamboo.

Soil management for bamboo
http://www.halfsidebamboo.com/gpage.html1.html#_Soil_Management

Mark

[Dean W.]

Great post, I too am having a problem w/ yellowing leaves on a couple of potted bamboos. I'll apply some Ironite and see if it doesn’t diminish the effect of chlorosis.

Dean

[ShmuBamboo]

A few points about leaf yellowing: I have a certificate in horticulture, and I was a landscape gardener for several years in Monterey, CA. I also grew many roses for years and have published a booklet and articles on growing Roses. I do not agree that bamboos are like roses... grasses grow somewhat differently than roses do, and you need to feed them for different reasons. You want to feed and purge roses in cycles during the growing season for blooms, and bamboo rarely blooms (never mind many times a year). You want to feed bamboo like lawns or pastures. Generally you want a large application in spring before shooting. I also believe that you should add nitrogen before and during rhizome season. This is my own deduction based on recent observations that I will get into here below.

One important thing to note when leaves are turning yellow: look to see if new leaves or old leaves are yellowing. New leaves turning yellow generally indicates an iron deficiency. Iron is not mobile in plants and becomes fixed in leaves. Iron tends to be deficient in alkaline soils because when the pH is above 7, iron becomes bound to the soil and is not available to plant roots. When the pH is below 7, iron is freely taken up by plant roots. So if your new leaves are yellow, feed them a fertilizer with chelated iron. Chelated iron will not bind with the soil, and thus will be available to the plants roots even in alkaline soil. Ironite is a good source of iron for plants if you have alkaline soils. I used to buy a 20 pound bag when I lived in California where I had alkaline soils and I spread it around my garden once a year. In the same way, acid soils fix phosphates, and as a general rule, you need to add extra phosphate in acid soils for the same reason that you add chelated iron in alkaline soils (except that low phosphate does not cause leaf yellowing; generally it causes stunted growth). I have acid soils here in Oregon, and I use superphosphate the same way I used iron in California.

Now, back to leaf yellowing: if older leaves are turning yellow that generally indicates that there is a nitrogen deficiency. Unlike iron, nitrogen is highly mobile in plants. When plants become nitrogen deficient, they will sacrifice older leaves and move the nitrogen from the older leaves to the new leaves and green growth. The solution in this case is generally to apply a nitrogen fertilizer. Also note that during certain times of the year, bamboos will shed their older leaves. Some types constantly shed their leaves, and no amount of fertilizer or iron will stop this process from happening. Phyllostachys bamboos in particular will shed all of their leaves once a year.

As for bamboo fertilizer timing... it is common practice to dump a large amount of fertilizer on bamboos before shooting season in spring. This is similar to grass pasture management, in that you want to time your application just before seasonal peak growth. Timing is tricky though. Cooler years will lead to later peak growth and your application should be made later in the year. Warmer years will result in an earlier peak feeding requirement. Heat summation is used to time the fertilizer application in pastures, and I believe that the same process can be applied to bamboo. A certain number of days above a certain temperature, and that is the time to apply nitrogen.

From my observations of bamboo, I believe that this time of year there is nitrogen demand for rhizome growth. I am testing this now, after seeing a lot of older leaves turn yellow in a lot of my bamboos recently. The timing for this application does not seem to have a correlary in pasture management, as pastures have generally flowered, seeded and died by this time of year. Bamboos typically do not flower and die annually, so this application seemingly has to be done after some older leaves start to turn yellow (your bamboos are talking to you!). So far the yellowing seems to have stopped after feeding.

As an aside... a secret to rose feeding... you want to feed and flush perpetual blooming roses (ie., hybrid teas, floribundas and grandifloras) in cycles to force growth, then withdraw fertilizer and stop growth, which will in turn set blooms. You can do this in 6-8 week cycles several times a year to get cycles of rose blooms. I got up to 5 rose blooming cycles this way in warm climates like San Diego. Feed, then in a week stop feeding and water to flush the nitrogen from the soil, water only until the blooms set and flower, then feed again, stop feeding, and so on. Roses are pigs too, and will dine on just about any type of fertilizer. I use 20-20-20 on my roses. For bamboo I use 30-10-10.

Hope this helps.

[Mark Meckes]

Thanks for the clarification ShmuBamboo and excellent explanation!
Yes, the only correlation I was referring to was the preference of roses and bamboo to soil on the acidic side, and even this is a very generalized statement as different bamboos, and probably different rose species vary in their tolerance to acidic/alkaline conditions.
And as you mentioned, flowering puts other demands on fertilizer needs.
Flowering of bamboo is (generally) quite seldom ... there are greater chances of seeing other 'bloomers' hanging from their branches ...
1253

The ability for a plant to access the nutrients it needs also varies greatly if a plant is growing in a confined container or in the ground.
And nutrient uptake of in-ground bamboo will also vary according to soil density (friability), and available moisture.

I have found that, despite having alkaline growing conditions, if the bamboo is mulched and given ample water, the rhizome roots are able to grow deeply into our alkaline clayey soil (we are on a hill so there is never standing water/oxygen deprived soil)
However during very dry periods more yellowing occurs, as if less available moisture leads to an increased concentration of alkalinity. (?)
Areas given supplemental watering in the same soil condition have less yellowing of leaves.

I have never actually measured our soil alkalinity, though this area is known for such conditions.
Our hillside also has intermitent calcified ancient seabed layerings containing fossilized clam shells etc.

I rarely add any "concentrated" fertilizer to our groves with the exception of organic mulch in various form, when available, which main difference is in retaining moisture during dry seasons and enabling roots to grow deep.
I'm sure I could pump up the size of our bamboo a notch or two using a high fertilizer regimen, but on a utlility perspective ...
... Gnarly boo is tougher boo.

Mark

PS ... recently found a local source of free "stable mulch" ... horse doo-doo, straw and sawdust :)
I may have to eat my fertive words if my runners begin to gallop. ;)

[Dean W.]

Hello ShmuBamboo and Mark,

Great tips, I believe I have a combination of iron/ nitrogen deficiency. These bamboos get watered every other day due to the hot Texas sun. Both the old and new leaves are yellowing. Maybe I'll add some miracid and see if that doesn’t do the trick.

Thanks for the extensive replies ;),
Dean

[ShmuBamboo]

Miracid is Miricle Grow formula 30-10-10. That is what I use on my orchids and bamboo here. It has chelated iron in it as well, and a boatload of nitrogen. It is formulated for acid-loving plants.

As for Mark's question about alkalinity increasing in low moisture conditions, I do not think that happens. pH is very difficult to change in soils. There are compounds like RAK that will radically change soil pH toward acid. Also here in the PNW where the soils are more typically acid, we use ag lime to shift soil pH toward the middle. But moisture will not change overall soil pH level. Excess moisture will leech the soil of nitrogen though.

Another aspect of leaf yellowing is potentially caused by plant genetics and growth habit. For example, I have this Pseudosasa longiligula that has light green to yellow leaves all the time. I thought it might be nitrogen defficiency, so I fed them with 30-10-10. Well, that just burned some of the leaves. This type of plant likes morning sun and shade (#3 on the sun scale), and they are growing in full sun. So? The solution for them having yellow leaves is to be moved into shady areas.

[sasa fool]

Shmu - My Ps. longiligula is growing in full sun - 90 to 100F hot sun for the past several weeks - and it is a beautiful deep rich green color, with no yellowing. We are in the severe drought stage and this plant has not been given any supplemetal water, so I suspect that yours may yellow for reasons other than the sun?

[Mark Meckes]

My only 2 bit comment is that when a container plant is growing in full sun, it's leaves will yellow faster than in-ground bamboo growing in full sun.

Maybe this is also because the container can also get hot with the sun shining on it, and I believe a plant's photosynthesis shuts down at high temperatures. (?)
Perhaps there's other benefits, besides having to water less, that nurseries grow (even sun-loving) plants with some shade cover during warm months.

Another issue regarding soil alkalinity/nutrient uptake is the PH of the rain or tap/irrigation water.
I have not checked my water here in central Texas, but I know, when living in Pennsylvania, that we had acid rain ... and acidic soil.

Mark

[ShmuBamboo]

Interesting thought... we have really really hard and very alkaline well water here. It is so hard it is off the charts on my hot tub water tester. I also have very soft neutral water from a spring that feeds a water line I can tap into as well. I will try watering them with the spring water and see if there is any affect.

Also point noted about growing bamboos in pots. It has been hot here this month and in the 90s today. My brother noticed that potted bamboos are far more suseptible to heat and cold damage than bamboos in the ground.

But one thing to note... Ps. long. is listed as growing best in sun zone 3 in the ABS source list. My Ps. long. are markedly more yellow-green in leaf than the Ps. japonicas growing next to them.

[TexasGrower]

One important thing to note when leaves are turning yellow: look to see if new leaves or old leaves are yellowing. New leaves turning yellow generally indicates an iron defficiency.


Nope, they are green.

My plants are getting spots on them. I'll try to get a good photo to post so people can see.

Update... Here are the photos...

http://s181.photobucket.com/albums/x293/joebannon/Bamboo%201/

[ShmuBamboo]

What you have there is not your typical iron or nitrogen defficiency. My first thought is heat damage or water stress (not enough water). It could also be damage from spider mites, as they dine when the heat goes up and will defoliate all kinds of plants in a hurry. I have some boos with similar types of leaves with those types of spots in sections of the plants, and they seem to have responded well to spraying with insecticide oil and insecticidal soap (my spider mite spray). The temperature needs to be below 60 degrees to spray this stuff though, or you can get leaf damage (we get cool nights here in the PNW). They also seemed to be in need of plant food too though. If it is water stress or heat damage, I would move them into a semi-shady spot. If they are types of boos that are less tolerant of sun then they need less light.

Also I have found that bamboo really needs a lot of food this time of year. My late summer feeding has really greened them all up. I am getting new shoots on a lot of my Phy.: aurea, nuda, vivax Aureocaulis, bam. Allgold, as well as the Ps. japonicas.