Plant Doctor Archive

Foliage, but no flowers

IN late autumn, I planted iris and tulip bulbs in containers. Lots of foliage grew very quickly, however the plants never flowered and are now dying down. What might have caused this?

THOUGH most bulbs are already flowering size when sold, it's possible yours were too small. When choosing bulbs at the garden centre, pick the biggest ones you can find as they will already have the flower bud initiated inside the bulb. Small bulbs may need another year before they'll flower. Tulips can be extra tricky, especially in mild parts of the country. They may flower in the first year after planting then not again. This is often because they don't experience a sufficiently long cold period to stimulate flowering.

You could try to create these conditions by storing tulip bulbs in a paper bag in the vege crisper of your fridge for 4-6 weeks before planting in May or June. Make sure you don't have fruit or tomatoes in the fridge too, as they can give off a gas that has a negative effect on the bulbs.

Plant tulips deeper than most other bulbs - around 15cm deep. With irises, don't plant them any deeper than 2-3 times the height of the bulb. Ideally use a specialised bulb potting mix for containers as the extra nutrients in general potting mix may encourage excessive leaf growth. And don't be tempted to plant bulbs too early, leave it until the soil has cooled, from late April onwards in most areas.

Reproduced with permission from the former Weekend Gardener magazine. The views expressed here are not necessarily those of the RNZIH.