Pereskiopsis cultivation problems

[Lee]

Hello Group,

I am seeking some cultivation help. I wish to grow my Pereskiopsis under optimal conditions to improve the rooting stock and
also achieve good growth for the grafted plants.

Please view the attached picture. I am not happy with how my plants look!

My Pereskiopsis grow in a 63mm pot, indoors under fluorescent lights for 12 hrs per day.(10watts/ foot) or 80 watts / 4ft x 2ft shelf. Shelves 15 inches high. 

Potted in grit, coir and perlite mix. Daytime temperatures 25 degC night 15degC. 

My plants are growing yellow leaves and they have a red pink cast to them. You can see that the new growth has smaller leaves and fatter stems. The original leaves are larger and used to be greener.

Could members advise if they think it it too much light?
Do you think the coir compost is the problem?
Perhaps they need more feeding and to be kept wetter?

I pot my Pereskiopsis in a compost mix that drains freely. Should I aim more for a water retentive mix?

If someone can advise on the best cultivation conditions for Pereskiopsis, it would be much apprecaited.

With best regards
Lee(inUK)

[fanecchissimo]

you should give a try to a good fertilizer.

with that power of light it is not probable you have a chlorosis problem.
do you use "plant spectrum" lights?

the pot also is quite little. you should think about bigger ones for explosive growth of the scion.

do you use hard water (GH) for your plants? because this could affect the absorption of nutrients..

to me the problem is P and K...
give them a try and let us know.

how hot it is on the apex of the plant?

[Lee]

Hello fanecchissimo,

Thank you for your help and advice, it is much appreciated.

I use 40w warm white fluorescent lights.

The pH of the water is dropped to pH5.5 with phosphoric acid and I feed at 300-450ppm.
uS/cm 600-800.

It is quite a low feed rate, I normally only
feed with tomato food. N-P-K 2.2.6

The apex of the plants are at room temperature as the light tubes are spaced and the plants grow the same across the
shelves.

It is quite noticable that the leaves are dense and small. The space between leaves (internodes) seems too short.

I think it may be a lack of food as you suggest and too much light!

The bigger pots is a good idea. The cuttings are rooted in perlite with no food before potting on.

Thanks for the suggestions.
Lee(inUK)

[Simon]

Too much light is not usually a problem with Pereskiopsis. It will grow well under 5000-10000 foot candles(I think that's what my light reader measures). That is 5 to 10 times brighter than the reading I get with the meter right up against a flouro tube.
I think it is a nutrient deficiency. The levels you are using are low. Most hydroponic crops are fed at over 1000 ppm.
I usually feed by putting 4 grams of slow release in a liter of soil.
Make sure you know the time period of slow release it can be 3,6,9 month. I go for 6 month then supplement with liquid feed after that. But if you are going to stick with liquid feed try 1000ppm or more every fortnight for perry. It is always interesting to trial different levels on different plants and observe the results. I have learned a lot from doing trials then when I find I am on a good thing I stick with it.
Two more things are nitrogen draw down of the growing media, this is when the organic matter in the mix decomposes and the microorganisms responsible use the available nitrogen. The peat you use will make this happen so i would probably recommend a well composted potting mix as your organic component. The other thing is cation exchange capacity(CEC). This is the growing media's ability to hold nutrient cations in a form that makes them available to plants. Once again it is the organic component of the mix that facilitates this. I am not sure of the CEC of peat but I think it is reasonable, good quality potting mix is excellent. Potting mix has a better structure too whereas peat(especially fine) tends to fill up the air pockets it media.
I also agree with Fane, pot size makes a huge difference as pereskiopsis grows to be a large shrub. I once put a 30 cm perry into a 10 liter pot, the first month average growth was 1cm per day in the second month average growth was 2cm per day!
I grow nine grafted perry in 19cm square 4liter pots and get excellent growth for several years.
Temperature is the last thing, perry wont grow optimally under about 24degrees C in my experience.

[fanecchissimo]

the light can't be too much with that power/surface ratio, it can be the wrong one.

try with a good fertilizer. peresk do like normal slow releasing for tomatoes and so on. i use for them about  NPK 18-20-30..

pH is quite low. you don't need so much acid. for you need some calcium too and magnesium for the plant... give it a try with about 6,5...

have a nice night

[Lee]

Hi Simon,
Thank you for your advice and help.
It is interesting to hear my problem will not be too much light.
My light levals are still quite low under fluorescent.

It would appear I may be 'starving' my plants as my feed levals are very low.
I was worried about root burn, but now I can increase the ppm.
I can easily feed at 1000ppm with liquid feed.
That would more like feeding non-cactus houseplants!

I understand your comments on nitrogen being used up by micro-organisms.

I pot in coir, grit and perlite. I do not use peat as it is difficult to re-wet when dry.
However the coir can hold good nutrient levels.
The CEC of coir may hold onto Calcium so I will have to watch this.

I will aim to grow them warm in larger pots.

Many thanks,
Lee(inUK)

[Lee]

Hi fanecchissimo,

Thank you for your  advice. I will raise the pH of my fertiliser and water.

It is interesting to hear that they require calcium.
The coir in my mix may be holding onto this due to the Cation Exchange Capacity (CEC).

I have aimed for low pH because of the other echinopsis I grow.

I think feeding may be where I am going wrong.
I will try larger pots and warmer too.

Many thanks,
Lee(inUK)

[fanecchissimo]

let us know if they do feel better!

[Lee]

Hi fanecchissimo,

Thanks for your interest. I will keep you posted.

With regards
Lee(inUK)