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Monday, 4 March 2013

Re-potting lotus ready for the new growing season


The lotus plant is a symbol of friendship, family, rejuvenation, hope, rebirth, fortune, purification and positivity. The rhizomes of the plant lie buried in the sludgy, smelly mud on the bottom of lakes and ponds. Rising up from the mud are the leaves and the strong stems, which come up through the water to support the heavily scented, beautiful flowers. This pattern of growth makes the lotus a very important and powerful symbol in Buddhism. It signifies the progress of the soul as the flower rises from the primeval mud of materialism, through the waters of experience, and into the bright sunshine of enlightenment (source). Though most water plants send blooms to the surface in this way, only the lotus flower sits up to one metre above the water’s surface, truly rising above it all (source).

Lotus are a primitive plant. The fossil record shows that 15 million years ago there were eight different species of lotus, which were later reduced to only two species – the Asian lotus (Nelumbo nucifera) and the American lotus (Nelumbo lutea). The spiritual, nutritional and medicinal importance of this plant in Chinese, Vietnamese and Indian cultures has made it the focus of extensive research and breeding programs. There are over 500 different cultivars of lotus in the world and the University of Bristol Botanic Garden has carefully chosen cultivars that show the range of flower forms and colours for its small collection.

Last week I met Penny Harms, Glasshouse Coordinator at the Botanic Garden, in the potting shed to see what she’s doing to prepare the Garden’s lotus collection for the next growing season. Penny and her team pulled the lotus plants out of the pond in October, where they have been sitting dormant in their pots ever since. Now, it’s time to give them some attention and get them ready to go back into the pond.

Penny is very careful when cleaning
the lotus rhizomes as any damage will
affect its growth.

Looking after Lotus

First, Penny tips the pots out, getting rid of all the old soil and gently collecting the lengths of rhizomes that wind around in circles within the pots. The rhizomes are then placed into plastic trays with lids that have holes to ensure they don’t get moldy. Over several days, Penny then sorts through each of the trays and pulls off any of last year’s rhizomes, which are brown and rotten compared with the cream-coloured healthy rhizomes.

“You have to be really careful,” explained Penny. “These are the growing shoots – this is a leaf here – so if you damage these, the plant won’t grow very well this year.”

Once the rhizomes have been cleaned they are potted up. Penny has prepared a special mix which is a loam-based potting mix to which she adds Bracken Down – a mixture of thoroughly composted bracken, bark and manure – and Osmocote – a controlled release fertilizer.

“Osmocote releases its nutrients over 18 months in a normal pot,” said Penny, “but because the pots are going into a really warm tropical environment, this will speed up considerably. It will release the nutrients over the summer, which is quite handy as these are quite hungry plants.”

Bonemeal is also added to the soil to give added support to the roots and chicken manure pellets are also added to provide more food. The lotus plants replenish themselves each year, so all of the rhizomes Penny showed me will be completely replaced by new growth this year. If the soil doesn’t have enough food and the temperature isn’t warm enough, the plants get weak and don’t really do anything.

“Last summer was quite poor,” said Penny “which meant there was less light and the glasshouse didn’t get as hot. We noticed that the quality of the rhizomes has gone down this year. I record the quality of the rhizomes when I pot them up and we’ve had some really strong rhizomes in the past. But this year, they don’t seem to have done anything – it’s as though they reached a growth plateau.”

Trays of lotus rhizomes. The tray on the left hasn't had
the old material removed yet, but the one on the right has
been cleaned and is ready to be potted up.

Placing lotus by the poolside

After the lotus have been potted up into clean pots with all new soil, Penny will write new labels and bring them into the tropical house. The pots then stand in trays of water along the side of the pool. This keeps the soil constantly wetted and after about a week of being in 25oC temperatures, the plants come into growth.

Once the leaves are 3-4” high and there are enough of them that Penny knows the rhizomes are growing, she raises the water level of the pool and moves the pots down onto a lower edge along the pool. This keeps the pots submersed in the warmest upper layer of water.
For the final phase, the pots are moved into the main pool where they sit on top of a stack of mesh trays. The water level is raised again so that it covers the top of the pots, but this has to be timed as well with the growth of the giant water lilies (Victoria) that occupy the large planters in the pond.

“Then that’s it for spring and summer,” said Penny “and I have to just cross my fingers that they do their stuff and produce beautiful flowers.”

The many uses of lotus

The rhizomes of lotus are rich in sugar and starches and contain up to 2% protein. They are sliced and roasted, dried or pickled. For medicinal purposes the rhizome is made into a juice or steeped in a tea and taken topically or ingested to stop bleeding.
The disc-shaped leaves and stems are eaten raw or used to wrap other foods, such as rice, for cooking. Medicinally they are taken to clear fever.

The flower has many uses. The outer covering of the flower – the calyx – is used in medicine. The petals of the flower are eaten and the male stamens are used to flavour tea and also contain the fragrant essential oil, which is extremely coveted. Lotus oil is three times more expensive than gold weight for weight. The receptacle, which houses the female parts of the flower and eventually the seeds, is aged and used for medicinal purposes.

The young green seeds have up to 16% protein content and are considered quite a delicacy. They can also be ground into flour to make bread or used medicinally to stop incontinence and digestive problems. The green shoots from the seed – known as the plumule – can also be removed and used for medical purposes.

There’s a lot in a name

When you visit the lotus display in the tropical glasshouse, you will notice that each of the labels has a series of names. At the top is the latin name (e.g., Nelumbo nucifera), then beneath that is the Chinese name (e.g., Xiao Foushou) and the translation (e.g., Small Buddha’s hand). Finally, along the bottom of the label is a description of the flower type (e.g., pink cup lotus). Chinese lotus flowers range from pink to white and some are cream or with a hint of green, but there are no yellow flowers in the Chinese lotus species. Yellow flowered cultivars, originate from the American lotus lineage.

The Botanic Garden has recently ordered some new cultivars from China to expand their lotus collection, including a yellow-flowered cultivar of the American lotus.

Date holder: Mark the 19th of May in your calendars as the Botanic Garden will be hosting a Fascination of Plants Day event

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