The leaves may be falling and the frosts starting to bite but it’s still a busy time of year at the Christchurch Botanic Gardens, we caught up with one of the curators there for some winter gardening advice.

Shizuka Cornelius has a huge passion for gardening, even admitting she’s ‘addicted’ so her role as head curator at the Central Rose Garden is a pretty good gig.

Her favourite part of the job is watching the garden come alive in spring but says all the hard work is done in winter.

Pruning

Shizuka says many people think winter is the quiet time of the year in the gardens, but the cooler months are the busiest time as they have to get all the rose pruning done.

“You need to cut them back to about a third of the height, traditional advice is to create a vase shape with the plant and thin the cane in the middle to create air flow.

“However, we prune to encourage as much flowering as possible, to do this we leave more cane in the middle and do a lot of liquid feeding.”

Feeding

The best thing to do in a rose garden is to use traditional gardening compost with a neutral PH and liquid seaweed.

“We spray the seaweed fertiliser all over the plant because the nutrition is absorbed by the leaves and stems as well, it creates a really healthy plant with glossy green leaves.

Shizuka says they never spray insecticide and rarely use fungicides.

“We want to encourage beneficial insects because they help the whole ecosystem, the sparrows and ladybirds eat the aphids.”

The rose garden is its own little ecosystem even on a cold day, bees are flying around and birds scurry around the garden – a big hedge around it keeps the temperature about two to three degrees warmer than outside the garden.

Dead leaves

Fallen leaves are a great way to get nutrients back into the soil.

“If they’re slow to break down what I do is mulch them up with the lawn mower and then put them back on the garden.

“But for roses it is different, you should remove all the fallen leaves from the garden beds because of rose rust we don’t want spores on the leaves to go into the soil.

During winter we actually spray the soil as well to ensure we are getting rid of the spores,” Shizuka says.

It's the perfect time to plant

She says autumn and winter are the perfect time to plant, flowering shrubs, roses and fruit trees.

“Bare rooted plants are the best because they’re faster to establish.

“Because the soil is usually moist in autumn and winter, if you do forget to water them the plants will survive.”

Design

Don’t love where your hydrangea is planted or think your rhododendrons would look better somewhere else – Shizuka says winter is the perfect time to shift plants around.

“You can’t do this any other time of the year otherwise the plants will die; I love moving things around and playing with design, it’s the best part of gardening.