The Tropical Fruit Forum

As soon as I had 3 inches of root.  Kumquats grow so slowly that it takes too long to get through the damp-off susceptible stages and are killed

ok, thanks, mine aren't that far yet, I'd say the roots are maybe almost 1 inch atm.

It’s only pumping 25 watts which is not very much right now. I’m using a 300 watt LED and I haven’t had any problems yet. Could it be damage from soluble salts?

Perhaps, I have no idea, that's why I put it up here, but maybe the nutrition I added has those.
Guess they're too young for that and I'll have to stick with root booster only then for now.

I’ve had some new buds sprouting out of a new scion die off too, and it seems that the meiwa kumquat likes to do this more than my other grafted varieties. Another bud growing out again later though. I think kumquats are fussy; I have had more difficulty getting their cuttings, seedlings, grafts to grow than any other variety. Maybe try a horizontal cleft graft. I think I will. I did this with sour orange on PT this year and it’s growing faster than my vertical cleft graft of same variety.

Well this was a purchased plant so I didn't graft it, it definitely was not the cleft graft they used though but other than that the plant is in good health, just like brian said, it's been doing nothing besides that shoot for a while, so I don't expect new growth until next year provided I can get it to survive winter (the rootstock needs much protection)

So I have a kumquat in good condition, nice green leaves, that recovered from root problems a few months ago. Since the new growth is looking very healthy I was hoping one day the scion would grow a new second main branch. Eventually it did, I noticed a tiny new bud growing at the bottom, well above the graft union (yes, I was very sure) but after a week just gently touching it made it fall off. Thing is, it's not from overwatering as it's planted in the full soil and in greenhouse, nor is it showing signs of overwatering ( no yellow leaves and no other leaves are dropping either).

I'm wondering if a sudden temperature increase from the sun suddenly being revealed after a few days clouds + rain and my greenhouse windows being at minimal opening to avoid excessive rain from entering (and the 80Km/h winds from destroying everything) may have caused this, even though it has a shade cloth against the window it's located near.
I really thought new growth should be more resistant, how are citrus in warm climates otherwise be able to grow? O.o (temperature in greenhouse was with clouds 23°C and without clouds 35°C, I have no option for ventilation, I try to open / close windows as timely as possible and yes I know there are automated windows systems, I just didn't take them)

I bet this will probably be perceived as the most stupid question ever asked, but i kept banging my head over it anyway.
One of my kumquats is grafted on a volkamerian rootstock, which is said to have a low cold hardiness of about -2 °C, but the scion is a nagami kumquat and kumquats are sead to be cold hardy to about -7°C (give or take, i may be a degree or 2 off but anyway)

My question is, does the scion take the cold hardiness of the rootstock (in this case, would it die at -2°C) or do both parts have different temperature tolerances?
With poncirus trifoliate i already know the scion inherits some of the cold hardiness but I don't know how it works when it is the other way around.

and yes I was planning to overwinter it in a semi sheltered environment with frost cloth but it's just to know if I need to equally protect it or add a few layers extra around the rootstock.

Incubator, it is not the water that causes the problem, it is the lack of rootzone oxygen that causes the problem.  When the soil breaks down and compacts the water plugs up all the air spaces.

I see.
Before I had bigger shaped clay granules (turface) at the bottom of my pots, someone in this forum i was told to remove them.
Granted they were unclean and of poor quality.
If adding the finer and cleaner seramis along with some gravel and pumice will provide a good texture I'm all up for it.

Living in southern England I have very similar climate to yours in Belgium.
I have been growing citrus for very many years and I now always use the following mix which is very free draining but requires frequent watering in hot weather. It contains no nutrients so I add slow-release fertiliser granules initially and every spring. I also water always with dilute soluble fertilser. I have included some links to suppliers in the UK so you can see what I use but you can probably find equivalents locally.
Following parts by volume:
2 parts clay granules. This is a type of moler clay about 2mm diameter. It is sold for bonsai but is much cheaper to buy in quantity as Sanicat cat litter or as a chemical spill absorber. See https://www.safetyshop.com/clay-absorbent-granules-safety-tread.html and https://www.petsathome.com/shop/en/pets/kitty-friend-pink-absorbent-cat-litter-30-litre
1 part coarse pine bark sold as reptile bark or orchid bark. See https://www.ebay.co.uk/itm/265209292884?hash=item3dbfb4a854:g:MHYAAOSwbu1g14zU
1 part horticultural potting grit  see https://www.homebase.co.uk/rhs-horticultural-potting-grit-handy-pack-5kg/12812882.html
1 part coarse perlite This makes the mixture a bit lighter but can be omitted. See https://www.ebay.co.uk/sch/i.html?_from=R40&_trksid=p2047675.m570.l1313&_nkw=coarse+perlite&_sacat=0

The last two are literally impossible to find here in bags.
Even horticulture grit is not known here.
We have the play/beach sand, river sand, any sand for construction, course draining sand (only available in bulk) , expanded clay pebbles for me hydroculture.
I don't know where to get that kind of bark but these things turn to compost after a while, which is not desirable in containers.
I know.... seems the commerce doesn't want me to make a better mix and just sell more common stuff.... anything special i have to get from Amazon Germany or France

I would like to give the following soil mix a try:
Cellmax terra soil mix
garden peat
brown peat
sphagnum peat
ground peat,
Coarse Perlite
Organic / Mineral Fertilizers.
pH (H2O) 5.0-6.5
EC 1.19 mS/cm
Organic/mineral plant food NPK 14-16-18. contains micronutrients
Water retention capacity: 600 ml/l

and add some more perlite, pumice and aquarium gravel to it:
https://www.amazon.de/-/en/Dehner-Decorative-Gravel-Aquarium-medium/dp/B01M5H2O7E/ref=sr_1_7?dchild=1&keywords=pflanzenkies&qid=1625591679&s=pet-supplies&sr=1-7&th=1

if that still retains one watering for weeks on end I don't know it anymore. Soil mix feels very lightweight though
and yes, unfortunately there is a limitation as to which components or materials I can get, even online. So sorry for not being able to get "just the right stuff".
I'll have to do a drainage and retention test with this later when I have time.

If "sand"  is used it must be quite coarse.  Children's sand box sand is not a good type to use.  Personally I do not use sand of any type.

Well, 3 years ago I found a Dutch website that discussed using 50% white sand and 50% compost, the white sand is indeed the childrens sand box type and it was awful, it kept sucking water in and did not drain, and the compost in containers caused fungus development too.
For reference here is the google translated site: https://translate.google.com/translate?sl=nl&tl=en&u=https://www.foodplanting.com/potgrond-voor-citrusbomen/

I've been through many of those miserable guides but if I can use the soil that you buy for seeds and cuttings instead and mix that with peat like pagnr said I should be better off because the Mediterranean soil I was advised is not suitable for our climate, you could compare ours to London. Wet well not always but right now they just said we have an extremely rainy and wet, humid summer

One of the soil suggestions I received from a nursery in Italy was the following:
- blond peat (about 60%)
- pumice (about 30%)
- some soil to get the right texture  (but he did not mention which soil) (about 10%)

Anyone's opinion on this?
I find this an awful lot of peat to be honest.

I am not an expert but I can relate some of my experience with root issues. If the citrus is in a large pot it is often hard to determine how wet or dry the soil is around the plants roots. I sometime grow a pepper plant or annual herb with thin sensitive leaves, in the same pot with a large citrus plant. When leaves lose turgor, the citrus needs to be watered enough to keep the pepper's leaves looking good but no extra water should be given. The tree doesn't suffer and it takes the guess work out of watering. I think watering a set amount is not good, you have to watch the plant's leaves and water when it indicates it needs water. Since citrus have thick leaves this is hard to detect. But a pepper is open about its requirements.

If the roots stays wet and are hot the roots will start to die. I have this trouble when my plants stay in the green house too long into the summer. The roots usually start dying off and a lot of root death can happen before the leaves start to show symptoms. But citrus are usually resilient and will grow back quickly if re-potted into fresh dry soil. Too high a ph will also be a problem for PT root stocks.

Yes, I think keeping an eye on the leaves is my best bet along with the finger in the soil .
I know peppers very well, I grow them for 11 years, but I can't add one to a citrus pot because mine grow.....huge O.o especially Aji Amarillo's, these plants grow like jungle bushes.

For now they're all stable, leaves look happy, the plants that lost all their leaves (2 kumquats) have already regrown them in one month time (alemow rootstock).
The keraji on PT is currently planted in the greenhouse soil and is stabilised, but growth is very slow but I was aware of this and need to be patient, shikuwasa on PT is also stable, a month ago some new leaf buds shrivelled (dried out and turned brown) while all other leaves still looked good, but that was because of the sun / heat so I'll have to wait till next spring for new growth.
The pursha, I was already told this is a very sensitive plant, is currently also stable, I did remove a lot of flowers so he can concentrate on growing, but I merely started this topic because I found it so weird, after all I done to correct my past mistakes that the soil is still moist for so long but since the air is quite humid here, I think that's the problem right now, none of our plants seem to need water right now.
I just hope we get some more sun again and then things will get better.

I was recommended by several european people to use Mediterranean soil for my citrus as it doesn't dry out too quickly and because the 5-1-1 soil won't work (we don't have the same kind of bark and it starts to compost and do nasty stuff)

I followed a guide from a dutch website https://www.allimone.nl/citrus-limon/  (which I had to purchase, since this pdf is not free) and in that guide they too recommended
- to cover the drainage hole of terracotta pot with something such as a piece of a broken terracotta pot
- add a thin layer of expanded clay pebbles to improve drainage
- use Mediterranean soil mixed with perlite
- water in summer : 1l for plants smaller than 0.5m and 4L for plants bigger than 1m each week (more if theres a heat wave)

turns out the core of the root ball is drying out faster than the soil around it, the soil in the entire container stays too wet so I'd need to wait 2 weeks but despite that root rot still happens.
Granted I am using for some plants pots that are too big, but for 3 I managed to get a pot that was about 5 - 10cm wider (no more than that) so that would be an appropriate upgrade. Yet these are suffering from the same problem too.

In response to these issues I first mixed my soil with a larger amount of perlite (30% or so) but the soil didn't dry out enough.
I started noticing leaf drop (as I posted in some earlier topics) and yellowing / browning branches and that told me root issues,
I repotted all of them and added another 30% pumice (4 - 8mm size was all I could find from a german bonsai shop on amazon ) to further improve drainage. While gently removing the root balls out of the soil, I noticed that the size of the root balls of some of them reduced , some even by 50%
I also removed the expanded clay pebbles as others here mentioned they do harm for citrus.
 
So my questions:
- since my drainage can no longer be improved because I already did what I could, how can I decrease the time for the soil to dry out? (we had a few weeks of hot sun but after that much cloudy and rainy weeks, during rain I place them under a roof outside so the soil doesn't get even more wet.
- watering amount: i know many will say this is difficult to answer, I even looked up a table to calculate how many galllons for the canopy size and that came close to the amount I  found in that PDF but I still think for a freshly bought citrus plant in a 20cm pot dimeter with height of 60cm of plant (as mentioned on the site of oscar tintori) that 1 liter / week is too much. I started giving 0.5 liter but still seems to be too much. soil won't dry. (it feels dry on the top until the first knuckle of my finger and moist below that, never wet or sopping wet, but moist for so long is not good for citrus)
Is is perhaps a better idea to water 250ml with an accurate cup in the center of the root ball / week so it gets less water and should be dry by the next week?
Because, I know many will say "water only when it's dry or when you need to, not at regular intervals" and that's fine for me too but if my plant has root issues from this then I don't agree.

PS: the shards to cove the holes I use are not flat, they allow water to freely leak out, because they're somewhat curved. it's just to prevent the soil from clogging the hole.


Is there anything else I can do? I put them outside in the morning sun as much as possible but right now our summer is awful, the air humidity is high and we need more sun. and if it' not that then we get heat waves for which these young and now stressed plants are unable to withstand.
Side question: I have a pursha that was bought in a 30cm pot, this plant was bigger, but lost half its root ball due to heat wave (40+°C in greenhouse) it's still alive but losing a leaf or 2 a day, it's still has a lot of flowers and I was wondering if it's a good idea to remove them so he can concentrate on growing. I don't mind not having fruit next year, I want healthy plants.