Plant Doctor Archive

Bulbs affected by weather

IN January my hippeastrum had six pretty flowers on very short stems just above the ground. Then in February it bloomed again, this time five beautiful flowers on a taller stem. Is this usual or a freak performance?

WITH many bulbs, the height of the flower stem is strongly influenced by temperature. Cool temperatures encourage longer stems while warm temperatures tend to keep them short.

Many hippeastrum bulbs sold here have been imported from growers in South Africa and while they should have been conditioned to flower soon after planting, the temperature, both in the air and in the potting mix, can affect stem height.

It's a good idea to keep hippeastrums in a relatively cool place for the first few weeks after potting, then move them into a warmer spot once you see the flower spike coming up. And to make sure you get a good show of flowers next year, feed them with a high-potash fertiliser after flowering until the foliage dies down. You can buy specialist bulb foods, but rose and tomato fertilisers also have relatively high levels of potassium.

Another good tip is to keep the bulbs fairly dry over winter. You can simply lay the pots on their sides in a dry part of the garden, such as under the house eaves, then when the bulb shows signs of growth next spring, stand it upright and give it a good watering.

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