Wellington City Council's Earthquake Resilience Programme Director, Neville Brown, says the decision has been made to start necessary work on the building in order that it be fully reopened for its visitor peak in the summer.
Picnic Cafe, which occupies one end of the landmark building, will be closed for three weeks for the first stage of the project. It is scheduled to reopen on Fathers' Day weekend (1 and 2 September).
Mr Brown says Council engineers have been working this year on designs to strengthen the 50-year-old steel-framed and glass-clad building.
The intention is to add extra framing and bracing to the existing frame to lessen flexing and movement in the event of a substantial quake. Some extra reinforcing of the building's concrete foundations will also be done. Some $150,000 has been provided for this project within the Long Term Plan.
"The work will be relatively quick and easy to complete," says Mr Brown. "Much of the framing will be prefabricated offsite and welded into place."
The work on the Begonia House has been scheduled as part of the Council's earthquake resilience programme - for which provision has been made in the Long Term Plan.
Councillor Helene Ritchie, the Council's Natural Environment Portfolio Leader, says she supports the strengthening work. "While it may be disruptive, this is luckily the quietest time of the year for the Gardens. It's obviously essential that the Begonia House - which hosts thousands of visitors a year, is brought up to current building codes."
The Council's Parks and Gardens Manager, Paul Andrews, says many of the tropical and fragile plants in the Begonia House will be temporarily moved to other hothouses. Other, bigger, plants will have to stay - but Gardens staff will continue to keep them watered and cared for.
"The same goes for the fishpond inside the building - it'll be looked after."
The Begonia House - Background
The Begonia House was built in 1961 with funding provided by prominent Wellington family the Norwoods. It followed the establishment, in 1956, of the Lady Norwood Rose Garden - named by the Council in honour of Lady Norwood for the support and services she and her husband provided for the city.
The building contains a wide range of flowers and plants and of course many types of begonias. Tuberous begonias, both pot and basket types, with their spectacular large colourful flowers, play the starring role, and dominate the displays during the summer months. More beauty is added by orchids, bromeliads, cyclamen, primula, impatiens and various bulbs.
The building is made up of two separate areas - one for tropical plants and one containing temperate plants. The temperate section, heated to a minimum of 15 degrees, contains seasonal displays of potted flowering and foliage plants. The foyer of the temperate house has long been a popular wedding venue.
The tropical section's minimum temperature is set at 20 degrees, and most of the plants in this section are permanently planted. It contains bromeliads - members of the pineapple family, aroids - members of the arum lily family and orchids.
The Tropical Waterlily Pond houses many aquatic water plants including the giant Amazon waterlily species Victoria amazonica and Victoria cruziana. The pond is heated to between 23 degrees and 27 degrees celsius depending on time of year, and is stocked with plenty of tropical fish, to keep algae down.