Winter tips for your garden
Winter is a quieter time in the garden, but much can still be done, from planting trees and shrubs to dividing perennials and preparing the soil for spring.
Gus Flower, our Horticultural and Operations Manager, shares some top tips about what to do in your garden during the winter months.
‘Winter is a great time for dividing plants, which is a really easy and cost-effective way of getting more plants into your garden. What do we mean by dividing? This is when we split up clumps of plants like perennials and replant a portion of them elsewhere in the garden.”
Winter is a good time to do this, says Gus, because the plants are not actively growing so any disturbance is reduced and they will be ready to put on growth when the spring warmth arrives.
How to divide your plants
Plants that can be divided include lilyturf (Liriope), rengarenga lilies (Arthropodium), asters, harakeke/flax (Phormium), geraniums (Geranium), daylilies (Hemerocallis), irises (Iridaceae), red hot pokers (Kniphofia), hosta (Hosta), hellebores (Helleborus), lungworts (Pulmonaria), as well as ornamental grasses.
Clumps are ready for dividing when they are well established after two or three years.
“First of all, identify if the plant is starting to look a bit too bulky. Because they almost don't look right when they're just getting that big. And then consider where to put the newly divided plants. Do you want to extend a drift of them? And if you want to start doing drift planting, then you can divide them, split them up, and replant to extend them.”
Four of the plants that you can divide in winter (clockwise from top left): Daylilies, Bird of Paradise, Kniphofia, and ornamental grasses.
To separate the clumps, start by carefully loosening the soil around the plant's outer edges. Clear away excess soil so you can see the roots then cut sections from the outer edge with a sharp spade or pull apart with two garden forks pushed in back-to-back.
The divisions should be replanted as soon as possible. Add some compost to the hole before dropping them in and give them water if the forecast is for dry weather.
Winter vegetables
In the veggie patch, winter is the time for winter crops like kale, cabbages, silverbeet, broccoli, brussels sprouts, broad beans, spinach, and onions. It is also a good time to prepare the soil for spring by adding some compost and organic fertiliser.
Mulching is another good winter activity in the garden. Getting weeds under control is a bit easier as they grow slower in the winter months, says Gus. Once the bed is weeded lay down some mulch. This will provide nutrients to the soil and lock in moisture as the seasons turn towards the hot dry days of summer. Top it up with some more mulch in late spring if needed.
Winter tree planting
Winter is also a great time for planting trees, says Gus, as they are generally dormant and there is plenty of moisture in the ground.
New trees either come in containers or bare-rooted. Container trees can generally be planted much of the year (if you can keep them well watered) but bare-rooted trees are dug up from the ground in the dormant months and sold without soil around their roots. Bare-rooted trees are generally cheaper but need to be planted quickly into the moisture-laden winter soil.
Gus says you should take a good look at the root system when buying a bare-rooted tree: “You want to make sure you've got some good fibrous roots on there, choose a tree that does, rather than going by the size of it, because a smaller tree with better roots will do better once planted than a big one with poor roots.”
“You want to be particularly careful to make sure that they have been held over in some dampness too, because if the roots dry out, that can be disaster.”
Gus says he isn’t an advocate of staking newly planted trees, no more than just a short stake to stop it blowing around too much.
“Something I’ve picked up over the years is that when you stake a tree, then that tree and the root system become a bit dependent on it. With only a low stake or no stake the tree and the roots underground start to respond to and grow according to the winds that move it about. If you support a tree too much the roots haven't had to fight and become tenacious to do their job.”
Gus says he has seen examples when the stakes are removed and the tree flops down as it hasn’t learned to hold itself up.
Winter pruning
Winter is also a time for some pruning deciduous trees as you can easily spot any damaged branches that need to be snipped off, says Gus.
“Have a look for any damage, or early signs of disease, as well as crisscrossing branches and overcrowding. With young or newly planted trees it’s important to think about any formative pruning, this is crucial in determining and allowing the tree to grow true to shape and habit. Time spent with secateurs and loppers is far better than time spent saws,” says Gus.
Some fruit trees, like plums, need to be pruned when the sap is still rising in late summer, while citrus should be pruned in spring, once they’ve finished producing, and apples and pears are best pruned in winter.
Garden planning
And lastly, use the quieter months to do some garden planning or dreaming. A visit to Hamilton Gardens for inspiration and ideas is a good place to start. Not only will you get to draw inspiration from gardens reaching back as far as Ancient Egypt you’ll also get the well-being benefits of being in a beautiful place, and everyone needs that in winter.
Take time to look around, appreciate the winter light, the sculptural winter branches silhouetted against the sky, or enjoy the blooms and bulbs bringing colour and charm to the Gardens.
