Ixia viridiflora

[Uli]

Dear All,


The form of Ixia viridiflora posted yesterday and today seems to be paler than the one I grow. Mine was raised from an autumn 2019 sowing and it flowered beautifully in its second year. I donated seed to the US BX in 2021. What this plant needs is ample water during growth and flowering and a dry rest only after the leaves have died down. This year the flowers were almost completely ruined by a hot and very windy spell, last year's performance was better.
My seed was purchased from https://www.owlsacreseeds.co.uk/ixia-viridiflora after a discussion on this list. Owls Acre stated that the corms are short lived and new plants should be raised from seed regularly. They also stated that they carefully selected the seed bearing plants. 
The enclosed picture is from 2021. Do you see the beetles? I checked the flowers yesterday. The center appears black but is in fact of very dark blue.
The second picture shows seedlings from a November 2021 sowing. They are in a 20cm pot and the tallest ones are 30cm tall, still growing. They will not be repotted until after flowering next year.

Bye for now 

Uli 

[Colin Davis]

I've found Ixia viridiflora to be quite easy and not at all short lived, given that it receives proper care. Having lived in both truly coastal and inland climates, I have experience with this species in areas that rarely exceed 75 degrees in summer, and areas that routinely get up into the low 100's/high 90's. I forgot I had posted about growing this species before, but re-reading that 3 years later I agree even more. Summer water has not proven helpful for me, and may even be detrimental. The only mature bulbs I have lost have remained too damp for too long into dormancy. Those that have had a completely dry and hot dormancy rarely perish, and have lived for years and years regularly producing offsets and flowering. That said, my best performance has been in large 7 gallon plastic pots that have a longer and slower drying off period once water is withheld in late May/June (Southern Oregon), but then I've seen great performance in smaller containers as well. By the time growth resumes in September/October the soil is bone dry, and I have excellent performance doing this. If you were growing in terra cotta pots you might consider watering once or twice in summer, but I really do not think this is necessary.

The single biggest factor for bulbs re-emerging in fall and flowering in spring is a hot dormancy period (or at least warmer). Ixia, as well as many other South Africans, really struggle to re-emerge without that summer heat during dormancy. In short -  this species wants sharply draining soil, full sun, lots of water during growth and a hot, dry summer dormancy. Mary Sue has previously discussed the difficulty of growing some other bulbs in her coastal climate, such as Lapeirousia oreogena - which literally shows up as a weed in pots here. Biggest difference is I get a very hot and dry dormancy period. I don't think the importance of summer heat can be exaggerated. Even if for you that means moving dormant pots to a warmer attic in summer, it will help.

Ixia viridiflora
-Soil - Typical bulb mix (although this species can take higher amounts of organic matter than others) of equal parts pumice, sand and potting soil (I use Fox Farms Happy Frog)
-Water - Ample water fall through spring (usually water once deeply as temperatures start to drop in late September, then resume regular watering once I see growth emerge, continuing through late May/June once foliage begins to wither/seed is collected)
-Light - Full sun (part shade in early fall and late spring in hot climates, but still full sun in winter)
-Planting Depth -  Around 3"
-Temperature (current location)- average 45-60 daytime in winter, nighttime lows in the low-mid 30's-40's. Has proven hardy to down to 16F for short and irregular periods (with frost blanket). I wouldn't want to try growing this unprotected outdoors in colder climates than 8b, I think i'm on the lower end cusp.
-Dormancy - June through September. In hot climates move pots into shade (full sun will cook bulbs), but don't stack pots as that can retain too much moisture for too long. In cooler climates that don't exceed 85F in summer, move bulbs to an attic or as warm a location as possible.

Colin

[Uli]

Hello Colin,

Thank you very much for your detailed information about Ixia viridiflora. As I have been growing it only since the 2019 autumn sowing, I still cannot comment on its life span. It seems easy to grow in my condition provided it gets plenty of water during growth.
I have a question concerning how you start them  in autumn. In one passage of the text you write that the new shoots emerge from bone dry soil but in another passage you mention a thorough watering in September.
Not only with Ixia I find the decision difficult when to start to water my winter growing bulbs in autumn. I do worry about them getting damaged if they start into growth too early and after that would they be stopped by a new spell of hot weather. 

Bye for now 

Uli 

[Colin Davis]

Uli,

Thats a great question, and even after 15 years i'm still on the fence. By the time September rolls around i'm itching to get fall bulbs started, but I try to wait until days are no longer in the 80's, which is usually very end of September here. Lots of winter growing bulbs naturally begin growth as temperatures begin to drop in August/September - the earliest being Oxalis and Lachenalia (for putting out root initials). In my opinion temperature is the biggest factor for signaling bulb growth, with moisture being the second.

To clarify about fall watering - the first watering in of bulbs is a very deep, thorough watering. If your soil is peat based, as many are, a summer with no water has made it very hydrophobic, so over the course of a day or two I give many repeated drenchings to try to get the entire soil column as saturated as possible. Once I feel the pots are sufficiently re-wetted, then I do not water at all until I begin to see leaves/shoots pushing through the surface. This is general advice too, not just for Ixia. Once there is visible growth on the surface, then I begin watering at regular intervals.

It's true that water + heat can be a lethal combination for these bulbs, which is why I generally stay away from all summer water. It MAY be beneficial, but without exact knowledge of your soil, container, container size, humidity and temperature it's risky business giving supplemental summer water. Last summer I had accidentally stacked my dormant 7 gallon pots of Ixia viridiflora directly on top of each other, and digging around in July showed that the pot on the bottom had retained far too much moisture and bulbs were indeed rotting. The pot on the top had dried as it should and all bulbs were in perfect condition.

Without knowing specifics I would recommend watering your plants starting in September, but I really feel that daytime temperatures need to be around 75F or lower, thats your best bet in terms of avoiding rot. Whether for you thats early September or closer to October, go off of that. Thats a conservative approach I know, but with the amount of bulbs I have I don't like to take chances.

Colin