This year I grew some forbidden black rice plants (Oryza sativa). I don't know what I am doing when growing rice, and I am certainly not in their preferred climate, so it was all a bit of an experiment.
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| Forbidden rice not yet ripe |
There is not much advice available for backyard rice growers, so I had to largely work this out myself which is why I am writing this blog post.
I had a few plants so thought I would do some comparisons, see what works better for me, and share the results. Hopefully someone finds this useful.
If nothing else, recording this here is useful for me in future years to remember what worked and what didn't.
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| Rice growing comparison |
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| Rice plants comparison |
I am told that growing this variety of rice in shallow water is done mostly to control pests and weeds, and this variety of rice performs much the same in shallow water as it does in the vegetable garden. Strangely I also read that shallow water grown rice tends to provide larger crops.
I divided some of my rice plants, I planted one in a pot of soil in shallow water, the other is in a pot of soil. Unfortunately this test was not overly great. The soil used was the same, but the colour of the pot is different, as is the shape, and its volume, all of which may have an impact on growth of plants.
I also had a few other rice plants in soil, and a few others in shallow water. Some are in full sun, others part shade. These two plants are growing side by side, and I figure it is easier to take photos of the same two plants time and again for comparison.
I took the first photo on 20 November 2025. Both plants were reasonably similar in size and health.
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| 20 November |
I pull out the weeds, and leave them on the soil surface to die and break down releasing nutrients back to the soil. The one in shallow water did not have issues with grass and weed seeds germinating, the water took care of that for me. From that perspective, shallow water grown rice was easier.
Another week later, and it became pretty clear which plant was performing better in the short term.
After a few months, in March 2026, I took the next set of comparison photos. The situation had changed since the initial comparison photos.
Shade grown rice compared to full sun
Rice Plant Growing Conclusion
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| 26 November |
Another week later, and it became pretty clear which plant was performing better in the short term.
The plant in shallow water with azolla is noticeably taller. The leaves are darker green, and the stem has more black colouration. This is black forbidden rice, the black means it is high in anthocyanin.
At this stage neither started tillering, and they were both far from flowering stage. There was still a long time left to run with this little experiment but it was interesting to see such a dramatic difference so early.
After another week the water grown rice was racing ahead. It was too early to know if this would have any impact on the vigour of plants later in the season or the grain harvest at the end of the season.
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| 6 December |
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| Black rice in shallow water with azolla |
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| Black rice growing in soil |
After another week the water grown rice was racing ahead. It was too early to know if this would have any impact on the vigour of plants later in the season or the grain harvest at the end of the season.
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| 14 December 2025 |
After a few months, in March 2026, I took the next set of comparison photos. The situation had changed since the initial comparison photos.
The plant grown in shallow water had about 3 large tillers, and the soil grown had about 5 large tillers. This may have been because the dry soil grown rice had a larger amount of soil, or it may be because this variety of rice performs better under dryland conditions, I don't know. I only count the larger tillers as they can produce grain, they also had a number of smaller tillers.
Interestingly, the water grown plant flowered and produced seed over a month earlier than the soil grown plant. I'm not sure if there is enough heat left in the season for the soil grown plant to produce seed before the first frosts come.
It is noteworthy that I had azolla floating on the water in that first comparison. If one grew better or worse than the other it may be due to the shallow water, or it may be due to the azolla.
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| Azolla comparison March 2026 |
As I didn't know how much impact azolla would have, I also grew some rice plants side by side in shallow water, with and without azolla. I only have a small number of plants, and limited space, so was not able to have many replicates of each.
Once the plants grew a little I increased the depth of water to the top of the container. From here I tried to keep the water topped up in both containers. The water evaporates fast over summer, the one that did not have azolla evaporated much faster. I did my best to keep both containers topped up.
Growing rice in shallow water with and without azolla.
I divided two similar sized rice plants on 29 November 2025. The one without azolla was perhaps a little larger, and stronger. It also was starting to tiller. These two were as close in size and health as I could find. While not perfectly identical, they were near enough.
I planted them in identical pots, in the same soil, and placed them in identical containers, and added water. This comparison was better than the first one as the conditions for this were as identical as I could get them.
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| The rice plant on the right is slightly larger - 29 November |
I left these pots so the soil could settle for a while, both had roots under water and the leaves were in the air.
Once they had settled in, I increased the depth of water, and added some azolla to one container. I added quite a bit of azolla so I wouldn't have to wait long before it covered the water surface. I didn't need to start with so much azolla, the azolla covered the water surface over the next few days, the growth rate of azolla is remarkable.
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You will notice the water without azolla also had a few algae blooms. The water turned green and soupy for a while. I don't think these blooms are great for plants, and I didn't notice many tiny things swimming among the algae. When I parted the azolla the water underneath appeared clear and was teeming with tiny life. While I don't know if this impacts the productivity of the rice plants, aesthetically having azolla and lots of tiny life is nicer.
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| Rice in shallow water - 06 December |
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| Rice in shallow water with azolla - 06 December |
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| Algae in the water that without azolla |
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| Both plants similar size at this stage |
One benefit to rice from azolla is that azolla sequesters nitrogen from the atmosphere, and puts it in a form that can be taken up by other plants. This type of nitrogen fertiliser would be otherwise expensive to apply, where azolla does this organically and for free.
I read a study https://pmc.ncbi.nlm.nih.gov/articles/PMC12149377/ indicating azolla has more benefit to rice than simple nitrogen fertilisation, apparently it also acts as a 'biostimulant'. We are only beginning to unravel this interaction, but it sounds like azolla is more promising than simply being an organic and free fertiliser.
In that study, growing azolla with rice resulted in the accumulation of small peptides, lipids, and carbohydrates in rice roots, as well as flavonoid glycosides and carbohydrates in rice leaves. Early research suggests that this may make the rice plants more vigorous and higher yielding. That early research indicates not only does azolla increase the amount of rice grain produced, it may also make the grain more nutritious. More research needs to be conducted in this field.
I am getting off track here, time to get back to the rice plant growing comparison. About two weeks later, the algae bloom had cleared from the water, and both plants had grown noticeably. The rice grown with azolla was taller, more lush, and beginning to develop more tillers. It was still very early in this comparison.
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| Rice plants with and without azolla 19 December |
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| This plant is growing well, but not as well as the one with azolla |
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| Clear water, lots of growth, it is going well |
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| Larger and healthier looking plant |
The water without azolla eventually cleared, and stayed clear for the remainder of the growing season. The other plant had azolla that grew into a thick azolla mat, the lower levels breaking down and releasing nutrients while the azolla on the surface continued to grow.
I had some issues with tiny birds getting into the greenhouse and messing with the azolla. I don't know if they were eating it, or bathing in the water and splashing the azolla out, or searching for feed under it. I made no attempt to stop them, I think having fairy wrens come into the greenhouse isn't a bad thing as they eat a lot of small insect pests.
In March 2026 I took the following comparison photos. The azolla grown rice had 6 large tillers, while the non-azolla grown rice had 3 large tillers. Each of these tillers could have eventually flowered and produced seed.
It is noteworthy that the plants with azolla had more tillers, and flowered several weeks before the ones grown in water without azolla.
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| Azolla rice comparison March 2026 |
Shade grown rice compared to full sun
I had a few pots of rice growing in full sun, and I had some in part shade. I wondered if in small pots perhaps rice would over heat and might do better under a little shade to keep the roots cooler.
I didn't persist with this for very long as it became evident that rice growing in full sun was far larger and healthier than rice in part shade. After a few weeks I moved the shade grown rice into more sun, and they almost caught up to the other plants.
I don't have any photos of the shade grown rice. They were just small seedlings, they grew well once I moved them to an area with more sun.
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| Rice seed heads forming in autumn |
Rice Plant Growing Conclusion
While I got some seed from my rice growing experiment, all my rice plants struggled to produce a decent sized crop this year, I think there are a few reasons behind this.
This summer, apart from a few days of extreme heat, was largely mild and dry. We had very few tomatoes ripen this year, presumably due to lack of consistent heat. I have a feeling if we had more consistent heat plus a bit more rain I may have been able to produce a better rice crop.
The pots I grew the rice in were far too small. If they had larger pots, they may have been better able to mature.
I initially worried that the rice plants may not get enough sun in the greenhouse, but this didn't seem to be an issue. The greenhouse grown plants didn't perform any worse than rice plants grown outside in full sun.
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| Rice growing outside in full sun - not part of the comparison |
When rice was grown on dryland, it initially performed worse than the submerged rice plants. As time went on, the dryland rice caught up and grew better than the flooded rice - but dryland rice also had issues with pests.
I had a large pot of soil with several rice plants that I did not take many photos of as I had no similar water grown comparison, I have a photo below of the end result.
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| This rice was all killed by pests |
Every rice plant in this pot was damaged by pests, and over time they all died. It seems in my garden that slaters/wood lice have a taste for rice plants, and like to eat out their base. I did not lose any of the flooded rice to pests, nor did I notice any pest damage to them at all. In this sense, the flooded rice was better as it suffered no pest damage in my garden where everything is grown organically.
Home grown rice performs best in full sun. Growing in part shade did not do well. This was not a great surprise.
Home grown rice in shallow water performed better with azolla than it did without azolla. This was to be expected as it agrees with results from much research into growing rice with azolla.
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| Rice not yet ready |
I only had a small number of plants this year, so this may be coincidence, but all of the rice grown in shallow water flowered and produced grain weeks before the dryland grown rice. I expected the dryland rice to perform better as I had them in in pots with a larger volume of soil, but for unknown reasons they are the last to produce grain.
The rice plants grown in shallow water with azolla were the first to flower, followed several weeks later by the shallow water rice without azolla, while the dryland grown rice only began to flower in late April.
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| Forbidden black rice seed heads forming |
I am told that this rice is perennial if protected over winter. I will try to protect some and see if any survives. I will have some in shallow water (to insulate against temperature swings), and some in damp soil, and see how they go.
Frosts are on the way, so I have moved all my rice plants into the greenhouse. My rice plants are all yellowing from the cold. I'm not sure if they will survive my winter. Not everything survives winter in the greenhouse as it is still very cold in there over night, but it is worth a try.
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| Rice plants turning yellow in cooler weather |
While my preference is for the rice plants to survive winter and to grow as perennials, I will also try to collect and store some seed to replant in Spring. They produced hundred of seeds, so saving some of this shouldn't be an issue.
Next year, if I grow black forbidden rice again, I plan to grow it in a few buckets of soil, or in large pots in buckets of water, similar to how I grow Chinese water chestnuts in buckets. Given a larger amount of soil I think these plants would perform much better.
