Oncos 2011

[Hendrik Van Bogaert]

Yesterday we had a lot of sun here in Belgium.
Two onco's start flowering: Iris sprengeri and Iris nigricans, both plants from our friend Janis.
As you can see no problem to send Janis some offsets of Iris sprengeri.
Hendrik

[Regelian]

Hendrick,

you have a knack for raising wonderful oncos in pots.  I've had much more success in a gravel garden.  Can you tell us a bit more about your potting regimen.  Mixture? Potting season?  Year round maintainance?  Your I. sprengeri is perfect.  I've not managed to keep it more that 2 years, so far.

[Luc Gilgemyn]

More beauties Hendrik !! 

[David Nicholson]

very nice indeed Hendrik. If only I could........................

[BULBISSIME]

You're right Jamie,
I don't have such a success with Onco's in pots in the greenhouse, only pots in the frame but much better in the open bed...
what is your secret Hendrick ?

[BULBISSIME]

Outside, in the bulb frame, Iris swensoniana, from Syria, is flowering ; as always, looks very different depending of the light direction.

[Lesley Cox]

Magnificent, Fred. Outstanding!

[Hendrik Van Bogaert]

Hendrick,

you have a knack for raising wonderful oncos in pots.  I've had much more success in a gravel garden.  Can you tell us a bit more about your potting regimen.  Mixture? Potting season?  Year round maintainance?  Your I. sprengeri is perfect.  I've not managed to keep it more that 2 years, so far.

The secret (?) is loam and akadama (I think).
I had the possibility to visit several countries where onco's grow; I saw that they always grow in heavy soils, mixed with chalk stones; the soil is not particularly poor!
So I decided to add a sandy loam in my mixture, together with akadama (Japanese clay pellets) - see google.
My mixture is: equal volume parts of split (here we call it Japanese split), coarse river sand, small dolomite stones  (yellow sun 8 - 11 mm), akadama, sandy loam, ordinary potting soil + bonemeal.
I use always clay pots; they stay just to the rim in a sand bed.
Watering must be done carefully, but due the presence of akadama most of the free water is quickly absorbed; so a few hours after a water gift my soil feels humid, but never wet; otherwise there is always sufficient water available during the growing season. I add sandy loam, because loam can absorb a lot of nutrients ... important to achieve strong growing plants
Potting season: October.
First watering after summer: as late as possible October - November (even December if possible)
I try to reduce leaf grow during winter, but that's not easy in my climate. So I use artificial led lights during the dullest months of the year, but I have my doubts if this make the difference.
And maybethe most important thing: everyday of the year I visit my greenhouse and check the plants....
Hendrik

[Hendrik Van Bogaert]

You're right Jamie,
I don't have such a success with Onco's in pots in the greenhouse, only pots in the frame but much better in the open bed...
what is your secret Hendrick ?

Frederic,
I think you must avoid as long as possible early leaf growth in autumn...
I received in December plants of the collection of Jim Archibald; they were in very bad condition and extremely dry.
I thought: impossible that such rhizomes will recover.
During this winter: no leaf or very little leaf growth.
Next week I will show you flowers! Unbelievable!
Hendrik

[BULBISSIME]

I agree with you Hendrick regarding starting growth time : they usually start mid september here which is too early.
This year I'll start to delay it untill december.
In the greenhouse, may main problem is temperature as they're grown with caudiciforms plants, so I have to keep minimum 9°C and sometimes more than 25°C durung winter days.

I've really more success growing them in the bed ( with rain protection) so I think I'll build another one to put all plants in this conditions.

[arillady]

I read that growers want to keep them from growing as long as possible but I find that they start growth without any holding them back here. Rhizomes that I have dug previously and stored in paper bags start growth by themselves and I NEED to put them in the ground. I am going to try to protect them in the middle of winter from too much rain (if we get it) and maybe a little frost protection too.

[ian mcenery]

As a person struggling to learn how to grow these plants (I only have a couple so far to kill  ) I find the information and experience of growers sharing their experience here very helpful. Thanks

[PeterT]

Hendric, when do your temperatures drop so cold that the Iris stop growing for the winter?
I repot in September because the warmer days and cooler nights at that time of year seems to stimulate root growth. That is too soon if cold weather comes late in December because they are growing for too long but if the cold comes early, and they are not well rooted, they suffer in the winter.
  I try to avoid a lot of leaf before winter by giving very little water once the plant is growing and recoverd from repotting. I give no water from the end of October untill warm weather in February.

[Regelian]

Hendrick,
thanks for the secret!  I've tried watering a clay slurry into the gravel beds to create a heavier, non-organic soil, but it does tend to soak up the water in Winter.  Not always good.  I've not tried akadama clay.  Does it break down or is it a lightly fired clay?  I know it is very popular for bonsai, but, other than the internet, I've never seen it offered.

I can't stop them from growing in the Autumn, actually, I have a lot of seed germination in Septembre to Decembre and most overwinter very well.  Generally, those with pure of more than 50% onco genes want to start growing early, while the regelias seem to wait until they have a freeze to start back into growth.  I find I. hoogiana very difficult, though, regardless of how I treat it.  Don't know why. I. stolonifera generally does quite well for me.  The last teo Winters have hit -15°C, which is bloody cold for Cologne.

[arillady]

Hendrick,
So glad that you got some of Jim Archibald's oncos to grow on. You seem to know exactly what to do for success with them.
Pat