May Gardening & Landscaping Guide

May Gardening & Landscaping Guide

Landscape Project Ideas for May

Create beautiful drainage

Ahead of the winter rain, now is a perfect time to install drainage in lawns or convert a poor performing one with a pebbled area.

Enhancing permeability is becoming increasingly important for cities where stormwater doesn’t always cope with heavy rainfall. 


Create even more beautiful drainage - lay JakMat in parking or walking spaces that get muddy in winter.

JakMat Geocell, designed in conjunction with DoC, is made from recycled plastic and its heavy duty construction can carry the weight of cars, boats and RVs. All you see is a beautiful pebbled area. 

Build a raised garden bed

Raised gardens are a great solution when the ground soil is heavy clay, or you want a more elevated garden to save your back!

Using Macrocarpa Sleepers or Trustwood Sleepers, raised beds are easy to construct and provide an optimum growing environment for flowers, vegetables, shrubs etc.

Fill them with our Premium Garden Mix for premium results!

General Gardening Tips for May

Loving autumn colour, but don’t know the trees? Take photos and use a plant identification app, resort to Google or consult the nearest garden centre. They’ll identify them and tell you whether you’ve got the right position for them in your garden.

May is a great month to match some of the more colourful NZ grasses and coprosmas to exotic trees with glorious autumn shades.

Grasses, both NZ and Australian varieties have become very popular in NZ gardens. Now’s a great time to ‘comb’ out dead bits, so there’s room for fresh growth in spring.

Mulching helps: a layer around prized plants neatens the look for winter and has benefits such as protecting exposed roots from cold, limiting weed growth and evenly dispersing heavy rain.

Plan for some winter scent – daphne, wintersweet, boronia and the deciduous viburnums will get the senses going.

May in the Ornamental Garden

Trees & Shrubs

Autumn colour is a beautiful thing on exotic trees. In warmer climates oaks, maples and liquidambars colour reliably.

Remove spent foliage of summer-flowering perennial plants and place compost around the crowns.


Tidy up dying foliage and flowers from dahlias, hardy geraniums, hostas and other summer flowering perennials.

Plant for colourful winter flowers using the cold tolerant polyanthus, poppies, primulas and cyclamen.

Remove the coarse, older leaves of winter flowering hellebores (winter roses). This helps bring light to the crowns where the buds are forming and gives a big display of flowers in mid-winter.

Leave old flowers and leaves on roses and hydrangeas now, they should not be cut back until July and August.

Get all the spring bulbs now, both in the garden and in pots. Pots of bulbs can be left in shadier areas until they sprout.

It’s a great time to replant the pots ensuring some eye-catching colour over the next few months. Use fresh potting mix and mix up bulbs, small grasses or ground-covers for texture and polyanthus, primula or cyclamen.

A favourite garden plant for dry shade is the NZ arthropodium (renga renga lily). Remove any diseased or old leaves and sprinkle lots of snail bait over the leaves because they love them.

Lastly in frost-prone areas, cover them with frost cloth on still nights.

Hedges & Grasses

Camellia hedges do well in Auckland’s climate. Early flowering sasanqua varieties make the best hedges.

Last chance to trim evergreen hedges before the cold hits. Spread compost around them and enjoy how their crisp lines give structure to the winter garden.

Remove spent leaves and old flower stalks from flaxes; rake dead grass out of native grasses to rejuvenate them.

May in the Fruit and Vegetable Garden


For vegetable planting you should now be using seedlings as some seeds may not germinate.

Plant brightly coloured chard, cabbages, sprouting broccoli and cauliflower. Keep an eye out for slugs and snails.

Sow Chinese Snow Peas from now on, ensuring you have a wall or a frame for them to reach their mature height of 1.8metres.

Keen to grow asparagus? Mark out a decent area (minimum 5 square metres) and add lots of compost and sheep pellets to the bed. The asparagus corms will be in-store next month.

Last chance to sow broad beans ahead of the winter months.


Strawberries are coming: Prepare the garden beds or pots with plenty of Garden Mix or add compost and blood and bone. If the garden soil has a lot of clay, gypsum will help break it down.

After harvesting the autumn fruits – feijoas, passionfruit and tamarillo – fork some compost around the roots of the plants to pep up the soil.

Feijoas are ready to eat when they drop to the ground. Too many? Share them around the neighbourhood!

Dreaming of a hardy tree, with fruit and autumn colour? Persimmon trees make excellent specimens with large leaves that turn orange around the same time as the fruit matures.

Plant raspberries, currants and rhubarb crowns. Rhubarb ‘Victoria’ is the most common and easy-to-grow variety.

A copper clean-up spray over fruit trees that succumbed to disease in the summer season is beneficial now. Rake up diseased leaves when they fall.

Herbs & Flowers

Calendula flowers are known as winter marigolds. They flower in the cold season, add great colour to the vegetable garden – and the flowers are edible.

Winter stocks, casseroles and soups can be flavoured by the hardier herbs that can take you through the cold season – bay leaves, rosemary, thyme and sage are easily maintained through winter.

Potted winter herbs by the kitchen door – thyme, rosemary, parsley and bay leaves are staples for infusing flavour in cold weather food such as casseroles and soups.

Building up good soil

Prepare beds for traditional mid-winter crops such as garlic, asparagus and strawberries. Compost and Blood & Bone are ideal – if your soil is on the clay side, add gypsum.

Plant Protection

Slugs and snails are still active in late autumn, so lay yeast traps (aka dishes of beer) or ground eggshells / coffee grinds around small vegetable seedlings.

New winter vegetable seedlings such as cabbage and broccoli need to be protected from late-season attacks by green looper caterpillars – check the undersides or the veins of leaves for caterpillars. If necessary spray or dust to eradicate them.

Check lemon and other trees for scale infestations on the backs of the leaves in the form of hard brown lumps. They colonise easily in dry weather and prevent the trees from growing. Spray with mineral oil.

Worm farms need to be prepared for winter cold – add an old rug or piece of carpet over the top to insulate the worms.

Cut down lupin crops at knee height and trim them into lengths of 15cm. Leave on the soil to break down and add nitrogen.

Remove diseased fruit and leaves from beneath the fruit trees to avoid spores carrying over to the next crop.


May Lawn Care

Clean up any leaves that fall on the lawn, as sodden leaves can aid the spread of disease and prevent air getting to the grass below.

A layer of gypsum over the lawn ahead of a wet winter can assist with ‘opening up’ the soil and enabling water to drain through it.