Pot culture of Haemanthus

[Helen Johnstone]

Hi
Having recently discovered the PBS I am now receiving packages with exciting bulbs in. However I am struggling to find information on the best growing conditions for some so could some one advise what compost mix do haemanthus humilis subsp hirsutus do well in? Will they be OK in a cold greenhouse with my other bulbs or would they benefit from some heat?

[ArnoldT]

Helen:

Glad you're enjoying the PBS BX/SX distribution.  Why not pose the question to the PBS list.  The person who donated them may be the best person to ask about pot culture.  I think we are a friendly group.   

[Helen Johnstone]

What a sensible idea hadn't thought of that, the conversations are always a bit over my head but will give it a try

[Maggi Young]

An excellent suggestion, Arnold  but since Helen lives in England and there are a number of UK growers of these plants around the forum, I understand why she has posed the question here.

And it is quite possible that the PBS donor is a member here too - like Jim Shields, for instance - who posts quite often about Haemanthus 

Jim's H. humilis humilis from June last year

Hans J. grows these in Germany, also forumist "Haemanthus" - also Angela, who lives in NE Scotland and Darren is great with South African plants in North West England....... all may have relevant advice for growing in England, I hope.

[Helen Johnstone]

Also I was hoping for a quicker response than the PBS often gives. Have bulbs need to plant as already in growth

[Maggi Young]

Looking around the forum to see what info there might be for Helen, I saw this and couldn't resisit showing this  pic here again - it's another of Jim Shields' - this time a sparkling white  Haemanthus humilis subsp. hirsutus -

[Helen Johnstone]

That is nice. I did do a search in the forum and PBS but couldn't find any advice

[Maggi Young]

I've sent out a plea for help , Helen!

[Maggi Young]

A reminder that back in the Haemanthus 2011 thread there are various photos of the bulbs of different forms from Jim S . again - what a great source of info he is!
http://www.srgc.net/forum/index.php?topic=6891.0

Must  get those drawn into their own place sometime.

[David Nicholson]

From "Growing Bulbs: The Complete Practical Guide" by Brian Mathew (Batsford 1997) and widely available, and cheaply, on the Internet based bookshops.

 "All the species [Haemanthus] are frost-tender so in all but the mild winter areas, they need to be grown in containers in a frost-free greenhouse........ The species I have tried appear to grow well in a sandy, loam-based soil with a minimum temperature of about 5C in winter"

[Jon Evans]

I grow most of my Haemanthus in a mix of JI no 1 or 2 and at least 50% coarse grit, in deep (rose) pots.  They make long roots which are retained over the summer rest, and are easily damaged, particularly when most of the root system is in your sand plunge and not in the pot.  They don't need a lot of heat, but I try to keep mine frost-free - the thermostat in that greenhouse comes on at +3C, and the heater usually manages to keep the frost out.  I have several seedlings of H. humilis ssp hirsutus which are flourishing, but need to be bigger, and  probably hotter and drier in the summer, before they flower.  It is the first of my Haemanthus to come back into growth - usually late July - but goes dormant early (March - April); during dormancy it needs to be kept reasonably dry but the roots are perennial so I tend to water the sand between the pots lightly once or twice during the summer.  I don't add any additional fertilizer; some of the South African bulbs seem to be extremely averse to anything of the sort, so better safe than sorry.  Because of the perennial roots, I try not to re-pot until they really need it, usually at the end of June when they are about to come back into growth; I figure any root damage will be less significant then. I expect the experts will point out the error of my ways, but my plants seem to be growing, and some of them flower every year.

[Maggi Young]

Quoting from from Jim's Blog : http://www.shieldsgardens.com/Blogs/Garden/index.html

"I grow a lot of Haemanthus. Since the climate here in central Indiana is not optimized for Haemanthus, that requires a greenhouse and some improvisation. Much of the information on appearance and all the information on culture in this article are based on my personal experiences.

I use one mix for almost all my bulbs, including all Haemanthus. I call this my Gritty Mix; it is made up of Premier ProMix (based on Canadian peat) + sand + granite chick starter grit in the proportions (by volume) of 2 : 1 : 1. It drains fairly well, but the peat does hold water and I have to pay attention to my watering schedule in winter. The granite chick starter grit is crushed granite with a mesh size of about 1/16 to 1/8 inch. (Do not use a grit with any chicken feed in it for this part of the mix.) The ProMix I use is type HP, for succulents, and has somewhat more perlite and possibly vermiculite in it than other forms of ProMix.

I feed almost every time I water, using a soluble fertilizer with composition 20-10-20 plus micronutrients. Our water has calcium in it to about 19 grains of hardness, so I do not add any calcium to the system. My fertilizer is Jack's Professional Peatlite, soluble, with a fairly high content of nitrogen as nitrate. Avoid fertilizers that contain nitrogen mainly in the form of ammonia, urea, and/or ureaform. High levels of phosphate are not needed, as most South African plants are adapted to growing in phosphate-poor soils.

Caring for the winter-growing species is the trickiest part. Do not water when the temperatures are too high; heat promotes rot. Use low levels of nutrients when you feed (100-200 ppm nitrogen, no higher!) Do NOT use organic fertilizers -- they promote growth of bacteria and fungi, which are not desirable for South African amaryllids.

After the fourth or fifth years, I move my Haemanthus gradually to larger pots. H. crispus will bloom in a 5.5 inch sq. pot, as will young bulbs of coccineus, but a large bulb of coccineus needs at least a 2-gallon (22 cm diameter x 22 cm deep) pot. Most bulbs are in 1-gallon plastic pots (ca 18 cm x 18 cm). Repotting can be done just at the start of the growing season, but even then major disturbance of the roots can cause the bulb to suffer. It is perhaps best to repot Haemanthus without disturbing the roots at all.

I have a lot of bulbs and plants in pots, and I use strictly plastic pots..."

[jshields]

Thank you, Maggi.  I would probably have rewritten that from scratch, and left half out.

I would like to point out that Haemanthus humilis of both subspecies, H. montanus, and H. carneus are mainly summer growing.  They should have a cool (but not freezing!) and dry winter rest, then resume watering gradually when the weather warms up again.

Jim

[Helen Johnstone]

Many thanks all for the advice. I think I have got the compost mix right but think maybe a deeper pot is needed, maybe a long Tom type? I do enjoy discovering new plants and this is such a good way to learn about them.

[PeterT]

I concur with most of the advice given here.
Haemanthus humilis can have very small bulbs -which seem to sit barely below the soil surface. I would recommend a good layer of grit on top of them to keep them anchored until they root.
I have found a potting mix made of garden loam,  coarse sand and grit  suits most Haemanthus well. (exceptions being albiflos, pauculifolius, (and I imagine deformis). Normally I grow them in 50/50 John Innes and fine grit (2-3mm) (or 3-6mm) for convenience - commercial John Innes has a lot of humus in it- but this has not posed a problem. I do not think that they like to get their roots too dry, even if the top of the plant is very hot so a little humus may even be a good thing. -Compare to the peat content in Jim Shields mixture.

 H. humilis seems to be dormant from early Spring until mid Summer. It grows well in a greenhouse kept frost free, I have not experimented with sub zero temperatures.  I know H. abiflos may withstand freezing, but it is a very different species.

I have had no problems with alkaline potting soils, nor with rot in Haemanthus. You can tell if you over feed as the leaves go a nasty dark blue/green -similar to the colour of over fed grass. I don't think that they need a lot of food though.
Rooting small or even not so small bulbs of Haemanthus is best done in cool, mild, gentle conditions,. Not in the heat of a sun baked green house.