If you want a stunning display of colour in your garden, growing gladioli in Australia is a fantastic choice. These majestic spikes, often called ‘glads’, bring vertical interest and vibrant blooms to your beds and make exceptional cut flowers. With the right know-how, you can enjoy their spectacular show season after season.
Australian conditions are actually perfect for gladioli. They thrive in our sunny climate with a bit of thoughtful care. This guide gives you the expert tips you need, from planting to picking, to ensure your glads are the envy of the neighbourhood.
Growing Gladioli In Australia – Expert Tips For Success
Success with gladioli starts with understanding their simple needs. They are corms (similar to bulbs) that love sun, well-drained soil, and a consistent feeding schedule. By following these core principles, you’ll set the stage for a brilliant display.
Choosing the Right Gladioli for Your Garden
There are hundreds of gladioli varieties. Selecting the right ones makes all the difference. Consider height, colour, and flowering time.
- Grandiflora Hybrids: These are the classic, large-flowered types you commonly see. They grow tall (often 1-1.5m) and have big, dramatic blooms.
- Nanus or Dwarf Gladioli: Perfect for pots, borders, or windy areas. They grow to about 60cm and are more delicate, often not needing staking.
- Butterfly Gladioli: Known for their striking, bi-coloured and ruffled flowers with contrasting throats. They are medium in height and very elegant.
When buying corms, always choose firm, plump ones. Avoid any that are soft, shrivelled, or show signs of mould. A larger corm generally produces a stronger flower spike.
When and Where to Plant Your Corms
Timing is crucial for gladioli. In most parts of Australia, you plant them from late winter through to early spring.
- Cool & Temperate Zones (e.g., Melbourne, Tasmania, Adelaide Hills): Plant from August to December. Successive plantings every few weeks will extend your flowering.
- Subtropical Zones (e.g., Sydney, Perth, Brisbane): Plant from March to May for an autumn display, or in early spring (August).
- Tropical Zones (e.g., Darwin, Cairns): Gladioli can be tricky in constant heat. Treat them as an annual and plant in your coolest, driest period (usually April-June).
Choose the sunniest spot in your garden. Gladioli need at least 6-8 hours of direct sun daily. The soil must be very well-drained. If your soil is heavy clay, raise your beds or grow in pots. A light, sandy loam enriched with compost is ideal.
The Step-by-Step Planting Guide
Planting gladioli corms correctly gives them a strong start. Here’s how to do it:
- Prepare the Soil: Dig the soil to a depth of about 30cm. Mix in well-rotted compost and a controlled-release fertiliser low in nitrogen (like a bulb food). This improves drainage and provides nutrients.
- Planting Depth and Spacing: A good rule is to plant corms at a depth four times their height. For most large corms, this is about 10-15cm deep. Space them 15-20cm apart.
- Positioning: Place the corm with its pointed end facing upwards. If your unsure, plant it on its side – the shoot will find its way up.
- Watering In: Give them a thorough water after planting to settle the soil. Then, wait for growth to appear before watering regularly.
Essential Care Through the Season
Once your gladioli are growing, a little ongoing care ensures top performance.
Watering and Feeding
Gladioli like consistent moisture, especially once the flower spike begins to emerge. Water deeply once or twice a week, depending on rainfall, allowing the soil to dry slightly between waterings. Avoid overhead watering to prevent fungal diseases on the leaves.
Feed them when the flower spike first appears. Use a liquid fertiliser high in potassium (like a tomato food) every two weeks to support strong, tall spikes and vibrant flower colour.
Staking and Support
Tall gladioli varieties almost always need staking. The heavy flower spikes are prone to bending or breaking in wind or rain. Insert a sturdy stake (like a bamboo cane) into the ground near the corm when planting, to avoid damaging it later. As the plant grows, tie it loosely to the stake at several points.
Pest and Disease Watch
Keep an eye out for common issues. Thrips are tiny insects that can streak the flowers and leaves with silvery marks. Treat with an appropriate insecticide or neem oil if you spot them. Rust fungus (orange pustules on leaves) can be a problem in humid areas. Ensure good air circulation, avoid wetting foliage, and remove affected leaves.
Harvesting and Enjoying Your Blooms
For cut flowers, harvest when the first one or two buds on the bottom of the spike begin to show colour and open. Cut the spike early in the morning or late in the evening. Use a sharp knife and leave at least four leaves on the plant to nourish the corm for next year.
Immediately place the stems in deep, cool water. Recut the stems under water at an angle before arranging. They should last over a week in a vase.
What to Do After Flowering
Post-bloom care is vital for perennial success. After flowering, continue to water and feed the plant with a general fertiliser. This allows the leaves to photosynthesize and rebuild the corm for next season.
In all but the coldest frost-prone areas, you can leave the corms in the ground year-round. Once the leaves have turned completely yellow and died down (usually in late autumn), you can cut them back to ground level. In very wet winter areas, lifting and storing corms is safer to prevent rot.
To lift corms: carefully dig them up, cut off the dead foliage, and let them dry in a warm, airy place for a few weeks. Then, brush off the soil, remove the old shrivelled corm from the base of the new one, and store them in a mesh bag or paper bag in a cool, dry, frost-free place until planting time.
Common Gladioli Growing Problems Solved
- No Flowers (Blind Corms): Usually caused by planting too shallow, not enough sun, or using a high-nitrogen fertiliser which promotes leaves at the expense of flowers.
- Floppy Spikes: Insufficient sun, lack of staking, or inconsistent watering can lead to weak stems.
- Small Flowers: Often due to overcrowding, poor soil nutrition, or using corms that are too small when planted.
FAQ: Your Gladioli Questions Answered
How long do gladiolus take to grow?
From planting, gladioli typically take between 70 and 90 days to flower, depending on the variety and weather.
Can gladioli grow in pots?
Absolutely! Choose a deep pot (at least 30cm) with excellent drainage. Use a premium potting mix and plant corms closer together for a full effect. Dwarf varieties are especially good for containers.
Do gladioli come back every year?
In most Australian climates, yes, they are perennial. With proper after-flowering care, the corm will regenerate and produce flowers the following season. In tropical zones, they are often treated as annuals.
Why are my gladioli leaves turning yellow?
Yellowing leaves after flowering are normal as the plant goes dormant. If it happens during growth, it could be overwatering, poor drainage, or a nutrient deficiency.
What should I plant with gladioli?
Their upright form pairs well with lower, mounding plants like dahlias, petunias, or marigolds, which can help hide their sometimes bare lower stems.