< Pat Clifford having fun

Season's End at
Royal Botanic Garden

by Pat Clifford
RBGE Senior Horticulturist
Click images to enlarge

Well, it's that sad time of year for those of us who look after tropical ponds in the far flung northern latitudes. The light levels are steadily dropping and all the aquatics are starting to feel sorry for themselves. 

The first plants to be removed were the Nelumbos. They stopped flowering about six weeks ago after a very impressive season where both plants produced around 15 flowers each.


With the light levels dropping the Nelumbos started to show signs of mildew and we knew it was time to remove them. We just have them labelled as Nelumbo cultivars as we are not sure which varieties they are. All we do for storing them over the winter is take them from the pond and leave them under a bench in one of our temperate houses, which has a minimum temperature of 10° C (50° F). There they sit drying out until we repot them in the spring.

< Nelumbos on their way to storage

Next to come out are the Nymphaeas. We had eight cultivars this year and they have all more or less stopped flowering. We take the large pots out the pond, prune off the leaves, remove the tubers, and repot them in small 8 inch (20 cm) plastic pots or baskets. They are then stored in a tropical glasshouse 16-20° C (61-68° F) water temperature. In the past we have tried dry storing them in peat but we seem to have better results this way. When the Nymphaeas are repotted into the large pots containing plenty of fertiliser in the spring and placed in the warmer water of the display pond 30° C (86° F), they burst into growth. 

Nymphaea 'Jack Wood'

N. 'St. Louis Gold'

N. lotus

N. 'Pamela'

My pride and joy, the Victorias, are struggling on although there is a marked decrease in growth. They should last until late November. This has been a strange year for them. They have had much smaller leaves but many more of them. This could be due to one or both of the following factors: 

Above, the Victorias in 2007
At right, the Victorias in 2008

1. The Weather.

We have had so much rain this year and therefore very low sunlight hours, e.g. the total sunlight hours for June, July and August 2008 was 359, compared to last year which was 419, about average.

2. The Fertiliser.

I ran out of my usual granular fertiliser and decided to buy some with a really high nitrogen content in the form of ureic acid, thinking naively that the more nitrogen the bigger the leaves -- not thinking the more nitrogen the more leaves, which could as easily have happened. 

There is another factor which is the variability which is inherent in any cultivar. What do you think? I must add that I cut all flower buds off until late June as I always do.

So now we have about four months when the pond looks a bit uninspiring, mainly inhabited by Eichhornia and Pistia. How do other gardens brighten their ponds up at this time of year?  

The pond empty

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