What to Plant in Autumn: March-May Garden Tasks

Spring might get all the gardening glory, but here's a secret every Kiwi gardener should know: autumn is actually the best time to plant in New Zealand. While your neighbors are putting their gardens to bed, you can be setting yourself up for the most spectacular spring display they've ever seen.

Think of autumn as nature's insurance policy. When you plant in March, April, or May, your plants have the entire winter to settle in without the stress of hot summer sun or the pressure to produce immediate results. The soil is still warm from summer, encouraging root growth, while the cooler air temperatures mean less water stress.

Your plants essentially get a head start. Come September, while spring-planted gardens are just beginning to establish, your autumn-planted beauties are already settled and ready to explode into growth.

The Autumn Planting Champions

Trees and Shrubs: The Backbone of Your Garden

Autumn is absolutely the best time to plant woody plants in New Zealand. Native trees like kowhai, pohutukawa, and totara establish beautifully when planted between March and May. These future giants of your garden need time to develop strong root systems, and autumn gives them exactly that.

For non-native options, consider Japanese maples for stunning autumn color, or evergreen camellias that'll give you winter flowers when everything else looks dormant. Rhododendrons and azaleas also love autumn planting – just make sure you're choosing varieties suited to your climate zone.

Perennials That Appreciate the Cool Change

Here's where autumn planting really shines. Perennials planted in autumn have months to develop extensive root systems, which means bigger, better flowering displays next year.

Agapanthus, despite their reputation as tough-as-nails plants, actually establish much better when planted in autumn. The same goes for daylilies, salvias, and lavender. Your autumn-planted lavender will be twice the size of spring-planted specimens by the following summer.

Don't overlook bulbs either. Daffodils, tulips, and crocuses need to be planted in autumn for spring flowering. The trick is getting quality bulbs – cheap ones often don't flower well in our climate.

Vegetables for the Cool Season

Your vegetable garden doesn't have to shut down in autumn. In fact, many vegetables prefer the cooler growing conditions that autumn and winter provide.

Broad beans are the superstars of autumn vegetable planting. Sow them in March or April, and you'll have fresh beans ready for harvest in spring when shop-bought vegetables are expensive and lacking flavor. Peas are another winner – both snow peas and garden peas can be sown through autumn for early spring harvests.

Leafy greens like spinach, rocket, and Asian greens absolutely thrive in cool weather. They'll grow slowly through winter but provide you with fresh salads when you need them most.

Month-by-Month Autumn Planting Guide

March: The Transition Month

March is your last chance for summer crops in most of New Zealand. You can still plant quick-growing vegetables like radishes and lettuce. For ornamental gardens, March is perfect for planting autumn-flowering bulbs like colchicum and nerines.

This is also the ideal time to divide and replant perennials that have finished flowering. Agapanthus, daylilies, and irises can all be lifted, divided, and replanted this month.

April: The Sweet Spot

April is arguably the best month for autumn planting in New Zealand. The summer heat has passed, but the soil still retains warmth for good root growth.

Focus on trees and shrubs this month. Fruit trees, ornamental trees, and hedging plants all establish beautifully when planted in April. The nurseries often have good stock available, and you'll beat the winter planting rush.

For vegetables, this is prime time for broad beans, peas, and cool-season crops. You can also plant garlic cloves for harvest next summer.

May: Winter Preparation

By May, you're moving into true autumn planting territory. This is the time for spring-flowering bulbs – get them in the ground before the soil gets too cold and wet.

Hardy annuals like sweet peas, calendulas, and cornflowers can be sown directly into the garden in May. They'll germinate slowly but develop strong root systems over winter.

Getting Your Soil Ready

Autumn planting success starts with proper soil preparation. After a long, dry summer, your soil might be compacted and lacking in organic matter. Here's how to fix that.

First, water your planting areas deeply a few days before you plan to plant. This softens compacted soil and makes digging much easier. Add compost or well-rotted manure to improve soil structure and provide slow-release nutrients that'll feed your plants through winter.

Don't forget drainage. New Zealand's winter rains can waterlog poorly draining soils, which is death to most plants. If you're dealing with clay soil, consider building raised beds or adding coarse sand and organic matter to improve drainage.

Planting Techniques for Autumn Success

The way you plant in autumn is slightly different from spring planting. Because plant growth slows down in cooler weather, you need to be more careful about watering and mulching.

Plant at the same depth the plant was growing in its container – this is crucial for woody plants. Water thoroughly after planting, then apply a thick layer of mulch to insulate roots and prevent weeds.

Here's a tip that many gardeners miss: don't fertilize heavily in autumn. Plants don't need lots of nutrients when they're not actively growing, and excess fertilizer can actually encourage soft growth that's vulnerable to frost damage.

Watering Wisdom for Autumn Plantings

Autumn watering is an art form. Your plants need consistent moisture to establish, but they don't need the frequent watering that summer plants require.

Water deeply but less frequently. This encourages roots to grow down into the soil rather than staying near the surface. Check soil moisture by sticking your finger into the ground – if it's dry 5cm down, it's time to water.

Common Autumn Planting Mistakes to Avoid

The biggest mistake I see gardeners make is treating autumn like a mini-spring. It's not. Plants grow differently in cooler weather, and your approach needs to reflect that.

Don't plant tender specimens too early. Wait until the risk of hot weather has passed. In northern New Zealand, this might not be until May.

Avoid the temptation to plant everything at once. Stagger your plantings over several weeks to spread the workload and reduce the risk of losing everything to unexpected weather.

Planning Your Spring Garden Now

Here's where autumn planting gets really exciting – you're essentially designing next year's garden. When you plant trees, shrubs, and perennials in autumn, you're creating the framework that everything else will build on.

Think about bloom times, plant heights, and colour combinations. That camellia you planted in April will be flowering beautifully by next winter. The agapanthus you divide and replant in March will put on twice the show next summer.

The Bottom Line

Autumn planting isn't just a good idea – it's the secret to creating resilient, spectacular gardens that'll be the envy of your neighborhood. Your plants get the time they need to establish, you get better results, and everyone wins.

Ready to create your own autumn planting plan? The key is choosing the right plants for your specific site and climate zone. That's where a professional ready-made planting plan can make all the difference, taking the guesswork out of what to plant where and when.