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Riceflower : Cutflower Cultivationcharacteristics cultivation disease drainage fertiliser harvest nematodes types varieties Ozothamnus diosmifolius, formerly known as Helichrysum diosmifolius, belongs to the daisy family. The shrub is native to eastern Australia and we have been cultivating it since 1988. It grows from 1.5 to 2.5 meters high, depending on the particular cultivar. While there are dozens of types, they fall into two major groups - broader leaf types (often associated with the coast or higher rainfall areas) and narrow leaf types with finer stems and leaves. All the types we are currently cultivating for the cut flower market are narrow leaf types. They are propagated from cuttings, as seedlings are much too variable. Good commercial cultivars have long, slim, straight stems branching into a number of flower heads. Flower heads are usually flattish, with dozens of pink or white buds opening into tiny papery-textured daisy flowers. The white forms have been easier than the pinks to grow so far as they seem less prone to problems. They also average more stems per bush. However, prices have tended to favour the pinks. Riceflower is drought tolerant when mature and it is frost hardy at Helidon. Most types flower in spring. Different cultivars flower at slightly different times, with most of our pinks flowering earlier than our whites. For the cut-flower market we have selected types where all the flowers on a bush are ready to harvest at the same time and all the bushes of the same type are ready to harvest together. Out-of-season flowers are ignored or pinched off. A bush should yield about 10 stems at first harvest, with the number rising to at least 40 in subsequent years. DANGER ! DANGER ! DANGER ! There are two things Riceflower hate - wet feet and root-knot nematodes. Water-logged soil or nematodes are both deadly. There is no point in trying to grow Riceflower until these two problems have been addressed, as you risk losing 100% of your plants.
Because we have nematodes, our soil is fumigated with methyl bromide before we plant. As the plants are expected to last for at least several years, even a small initial infestation of nematodes in the soil would soon build up to killer levels. None of our types shows any resistance to nematodes. We strongly urge prospective growers to have their soil tested for nematodes before planning any further, as the high cost of fumigation needs to be allowed for.
Growers use a variety of cultivation practices, but good drainage is essential. We hill our soil. There are no well-established rules about spacing, so we plant 80-100 centimeters apart to match the trickle irrigation spacing. Our rows are 4 meters apart to allow easy access for the tractor for spraying and slashing, and the utility for harvesting. We grass between the rows for wet-weather access and weed control. Grass between the plants is sprayed from time to time with Gramoxone. Thistles and other fluffy-top weeds must be constantly destroyed, as they cling to Riceflower leaves and have to be picked off during packing. Bindweed is another of our problem weeds. A single missed bindweed can take a long time to unravel from the stems. A lot of maintenance time goes into spraying and chipping or pulling weeds.
It is important to pinch out the young plants several times during their first few months to encourage extra branches and a low bushy shape. Watering is essential for young plants, but be careful not to over-water. After the first few days taper off to weekly watering until they are growing strongly. Once they are well established they may only occasionally need irrigating. Despite the worst drought in memory, our mature plants were watered only three times during 1993.
The use of fertiliser will depend on the soil, the quality of the water and the rainfall. Growers in different areas will need to experiment to find what works best for them. It seems from the limited work done so far that nitrogen and iron chelates are important to combat a tendency for foliage to go yellow, especially the re-growth after harvest or the flush of growth after rain. If soil pH is too high, nitrogen and iron in the soil may get locked up so that the roots can not absorb them. Where soil alkalinity blocks the uptake of nutrients through the roots, iron chelates, nitrogen and complete fertilisers can be applied as foliar sprays but check the label on iron chelates carefully. It needs to be specifically recommended (1) for use as a foliar spray, and (2) for use with high pH soils.
We find the best time to plant out cuttings is from March to July, although we have planted them out during every month except November and December. We do not know how long they live. We still have some good producers that were first harvested six years ago but there are more lost every year. We have had no problem with Phytophthora, although p. cinnamonii devastates waxflower here. However, the Queensland D.P.I. has isolated p.cryptogea in some plants in N.S.W. and S.A. There are crown and root rot problems which have not yet been unravelled. Certain types seem more resistant than others. Two other problems seem to be associated with root and crown rot; strangulation, where the plants were pot-bound before planting out and the twisted roots eventually choke each other; and infection entering through splits where small branches join the main stem. Insects are not a major problem here. A few days before harvest begins the bushes are sprayed to get rid of as many insects as possible. Hopefully, being dipped in insecticide during packing will get rid of any that remain. Harvesting: Riceflower which are planted in time to catch our autumn / winter growing flush are ready to harvest the following year. We start harvesting here about mid-September. Each type flowers at a slightly different time, so we check regularly (daily as harvest approaches) so that we can cut the flowers at the best time for marketing. We cut when the most mature buds on the central stem are just beginning to split and show their anthers. Buds picked too young will droop, but if they are left too long they open and the quality drops sharply. Maturing anthers usually turn off-white to brown, and the open flowers dry out and then shatter with handling.
We harvest with a hedge trimmer on a chain saw motor which must be tuned to suit. The first year we cut 12-15 inches above ground level to give the plant a good framework for future years. The semi-mature wood produces good sturdy shoots, providing we leave a branch or two or some low branchlets to feed the plant until the new shoots mature. Each harvest we take care to cut a little above the last year’s cut as they only seem to re-shoot from semi-mature wood. The "nurse branches" which were left to nurture the new shoots are trimmed off a couple of months later. Back at the shed, the stems are cut to length with compressed air secateurs, then bunched and dipped in an insecticide/fungicide mixture. After draining, they are packed in boxes ready for the cold-room. Ideally, we try to have the boxes on the forced air cooler two to three hours after the flowers were cut in the field. We do not pulse in water, or STS, or any other solution.
Up until now, we have sold all of our crop in Japan. We market stems from 60 - 100 centimeters long. 60cm stems are packed 10 to a bunch, the longer ones 5 to a bunch.
Two of our cultivars have been released for purchase under Plant Breeders’ Rights. "Cook’s Snow White" is our best type, with straight dark stems and good white flower heads. Many of our mature bushes have up to 100 stems each.. "Cook’s Tall Pink" holds its colour well, and provides the long stems the Japanese market likes.
These notes are intended as a guide only. Riceflower may have many different reactions to different conditions, and intending growers are urged to plant a small crop initially to check its viability in their particular area. We have described it as we find it, and take no responsibility for differences in plant characteristics or management needs that other growers may find. We are always interested to hear from other growers who are adding to the pool of knowledge about Riceflower that is gradually accumulating. © Graham and Esther Cook March, 1994 Cook’s Flowers M.S. 464 Helidon Qld. 4344 Australia tel. 07 4697 5130 fax 07 4697 5291 |
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