Turn the compost heap

If your heap is more than three months old it’s likely that there’ll be some usable compost at the bottom as plant materials break down faster in warm weather.

I make ‘‘cold’’ compost in a plastic bin as I don’t have enough material all at once to make a ‘‘hot’’ heap.

Turning the pile every month or so gives the uncomposted bits on the edges a chance to catch up with the material from the middle, which breaks down more quickly.

Turning also keeps the pile aerated, as composting microorganisms need oxygen. If your heap is smelly it’s likely to be decomposing anaerobically (without oxygen).

Take out any lovely, crumbly finished compost. Layer the rest back into the bin along with more plant material and a sprinkling of lime, manure, sheep pellets or blood and bone as an activator to get the heap going again.

LEAVE FERNS ON ASPARAGUS

If your asparagus bed resembles a fernery, never fear! These tall, wispy ferns are formed from unpicked spears and their purpose is to provide the crowns in the soil below with energy (through photosynthesis) for the following season’s spear production. While the ferns are not particularly pretty, they have a vital function so don’t be tempted to cut them back until they have turned brown and dried off around mid winter. When it’s time, cut the ferns back at ground level and add to your compost heap.

This is also a great time to lay down thick mulch to help suppress weeds. There’s no need to feed asparagus during winter – wait until it bursts back into action in spring, when the spears start emerging.

If you want to start an asparagus bed, now is the time to start building up the soil. Dig in loads of well-rotted manure, seaweed or blood and bone, compost and pea straw.

Let it break down until planting time in spring.

You can buy dormant two-year-old asparagus crowns in winter, but the best time for planting in the garden is when the soil temperature reaches 12C in early spring. Instead, bed these crowns into a tray of potting mix to save risking them rotting in the wet, cold winter soil and plant once conditions are more suitable.

Crowns are fairly expensive but they will save you several years of waiting until you can harvest.

However, if you’re patient and have time, asparagus grown from seed can provide many more plants for a fraction of the cost.

Asparagus is slow to establish, but once it is, a well-nourished bed will keep you in tender spring spears for at least 20 years.

WINTER HOMES FOR WILDLIFE

Winter is a tough time for the insects that pollinate our crops, eat pests and bring interest to our gardens. Some avoid the issue by hibernating or pass the winter as an egg or a pupa. Others require a cosy place to hunker down and also need food and water.

Bumblebee queens look for a cosy spot under leaf litter, in old mouse holes, or a compost bin to spend the winter. In early spring, the queen goes on the lookout for a more permanent position for her nest, so get a bumblebee hotel ready.

We¯ ta¯ are gobbled up by rats and hedgehogs and need safe retreats in we¯ ta¯ motels.

Bees and pollinators are still about in winter. Include flowering trees and shrubs

GET GROWING

This column is adapted from the weekly e-zine, get growing, from New Zealand Gardener magazine. For gardening advice delivered to your inbox every Friday, sign up for Get Growing at: getgrowing.co.nz

in your garden to supply nectar. Tree fuchsia, five-finger, wattle and sasanqua camellias cover the winter hunger gap.

DIG UP DAHLIA TUBERS

Decreasing day length in autumn triggers dahlias to store energy in underground tubers which lie dormant over winter ready to grow again next spring.

In colder areas it’s best to dig up the tubers after the first frosts have blackened the leaves so the tubers don’t rot in cold, wet soil over winter. Split large clumps up, keeping some of the crown as a part of each section as this is where new shoots arise in spring. Rinse the tubers off and after drying, store them in a cool, airy place until replanting in spring. Label them by colour and height so you can plan your garden layout in spring.

In warm frost-free gardens with good drainage, dahlias can be left in the ground for several years. Now is a good time to move plants or lift and divide crowded clumps. Replant or store over winter as above.