Hello; A brief introduction here, and a belated reply to Oliver Sparrow's comments as below.
I live in Tauranga, New Zealand and "across the river" from another member here knowledgeable in Disas... Been growing cacti, orchids, bromeliads etc for about 45 years at a hobby level. Many of the names on OGD are familiar to me from the OLD list in its heyday. I also subscribe to another list - see http://www.orchidspng.com/index.html - a very nice one where everyone is particularly gracious, and the Pleurothallid List. Like one or two others here I've been on a search for an ideal, trouble-free method of growing these plants, particularly orchids - at long last I found what is now proving very promising on Ray Barkalow's site http://www.firstrays.com/semi-hydro.htm - Which brings me to Oliver's point. I've been trialing several types of plants - orchids, epiphytic cacti, Hoyas, miniature daffodils and other bulbs in Ray's semi-hydro system using Hydroton expanded clay pellets. It's early days yet, but results are encouraging to say the least; e.g. cuttings of whatever type just don't rot but pour roots into the substrate mostly regardless of the (relatively) winter temperatures and day-length. (I think the key success element with semi-hydro is low CO2 around the roots - this is explained better on the semi-hydro site.) The main aim was to establish a nutrient level which would give optimum root development, as well as appraising the semi-hydro system. The containers I use are two sizes of ex-cat food, transparent, square plastic 'squat-pot' variety which fortuitously seem to resist two or three years' worth of UV light. There's a section on Ray's site covering MSU fertilizers http://www.firstrays.com/msu_fertilizer.htm - the main principle as I understand it is that a reduction in the phosphorous part of the NPK ratio actually improves flowering and growth in orchids and other plant types. On the assumption that a good root system is a desirable basis for a healthy plant, I took the opportunity to study the root growth of fast-developing plants at this time of year (in NZ) in transparent semi-hydro containers, using spring bulbs mainly - orchids are slow to respond - but it soon transpired that what I was about to observe applied to cacti, Hoyas, Begonias etc as well although these should be 'out of season'. Local tap water pH-adjusted to around 6.5 with citric acid measured on average 55ppm. Roots growing in this alone were fast-growing as expected, seeking nutrients, but thin and without root-hairs. Application of fertilizer (the nearest I could get to the MSU stuff was some Peters, I think, NPK 17:8:14 obtained from Ron M.) at 300ppm caused the roots to almost stop developing whereas the plants continued to grow quite happily. A reduction of fert. strength to about 150ppm caused a dramatic change in the roots' behavior - they grew fast again, but thicker and with root-hairs extending though space onto adjacent Hydroton pellets. I guess they thought they were in real dirt. Remember that about 50ppm of this is from the original water (calcium and magnesium citrates! - the plants love it) so true fertilizer concentration might be around 100ppm. Plants get watered with this 100% of the time. This may be the optimum nutrient level for a good root system covering different plant types, but obviously a couple of growing seasons will need to pass before the jury's totally out - particularly since the ppm count used here is unexpectedly low... and someone else might get different results. So you might see that I saw at least some parallels in Oliver's posting. Regards Dave - Days getting longer; looking forward to _true_ Spring Oliver says: >To get off overheated personalities, could I ask about people's experience with fertilisers? I have been trying a regime of sharply restricted nutrients and I have to say that I am impressed by the results. Mind you, this is a trial that is only in its second year, so one cannot generalise. However - for example - Grammatophyllums that had one-two spikes in previous years now have around a dozen, and this is far from unusual. In addition, there is less growth but it is woody and firm, with no rot in evidence. Roots growth seems much enhanced. Compost seems to be more stable. >The previous regime was a weekly light dose during all of the growing season. Now, they get fertiliser once every two weeks, starting from when the growth is firmly under way and ceasing before the Autumn slowdown. I could not recommend this to a commercial grower, as the rate of development is slow and the number of plants that you can push out is correspondingly less, but where you are looking for solid plants and flowers, it seems a winner. >I have also been exposing some plants - Cymbidiums in particular - to much brighter sun than hitherto, insofar as the UK can generate this. Leaf leangth has halved, but width and thickness are increased - particularly thickness - and pseudobulb size has also increased. They look much more like field plants. >Thoughts? <
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