How to plant gladioli for summer
Gladioli or sword lilies produce tall, elegant spikes of funnel-shaped flowers above sword-shaped leaves. Must-have for any perennial border, they are particularly fabulous planted amongst grasses, alliums and camassias in the mixed prairie, cottage or modern garden. They also make excellent cut flowers.
Plant around 15 to 20 cm deep and approximatively 10 to 15 cm apart in fertile, well-drained soil in full sun — adding grit or sharp sand to aid drainage and allowing for around 30 to 50 corms per square meter. When the flower spikes appear, water every couple of weeks with a high potash fertiliser. Protect from strong winds and provide a good layer of organic mulch in late autumn. Lift and divide as needed every few years; pick off the bulblets and transplant! It will take them a few years to flower.
Always unpack bulbs on arrival and store in a cool place until ready to plant. Take care! Gladioli can cause skin irritation, always wear gloves when handling and planting. They are poisonous and should not be eaten. They can be harmful to dogs and cats.
Potential problems, pests and diseases:
- Aphids: these sap-eating insects can weaken plants and spread viruses. Whenever possible, pick off by hand using gloves.
- Thrips: these microscopic insects will suck the gladioli's sap, causing the leaves to fleck with white and later preventing the flower bulbs to open. As soon as you notice any signs of this, cut back all the foliage and destroy. Both organic and non organic sprays will be able to help control the attack.
- Botrytis/grey mould: this fungal disease usually caused by excessive moisture, warm temperatures and poor air circulation can initially be seen as brown spots/grey mould on the leaves and stems. If you spot any signs of this disease, immediately remove affected bulbs/plants and destroy. Botrytis is an airborne virus and can spread rapidly in the breeze so do not compost infected material.
- Viruses: these attacks spreads from cucumber mosaic virus and can especially affect your corms if they are planted on an allotment.