Spring bulbs

Hippeastrum propagation

Perfect chips for finer flowers

Despite their exotic appearance, hippeastrums are not difficult to propagate at home as long as you start off with clean, healthy bulbs.

Although Kew is home to one of the most extensive collections of plants - and plant knowledge - in the world, we often work with others who specialise in particular plants. Holders of the National Collections of garden plants are often amateur plantspeople with tremendous expertise. Veronica Read, who grows the National Collection of Hippeastrums, advises on propagation and care of these striking bulbs.

'It was a visit to the Keukenhof garden in Holland in 1993, that first inspired me to grow hippeastrums, and I now have a collection of over three hundred plants,' she says. The collection can be seen everywhere - on the window sills, tables and even the fire hearth - in her flat in north-west London.

You can propagate hippeastrums using many techniques. Seed is favoured by breeders creating new hybrids and it can be a fun method to try. But simpler and more reliable are two vegetative methods of propagation - offsets and chipping.

Offsets

Offsets are new bulbs produced by the parent plant. 'You know if your plant has produced a new "bulblet" because new, separate leaves begin to emerge from the compost, to the side of the mother bulb,' says Read. It is relatively simple to remove the new bulb and the growth it has formed.

'Carefully detach the bulblet, causing as little damage to the new roots as possible. Pot this new bulb up, water in and be patient, as it can take a number of years before the new plant will reach flowering size.' Such simplicity, however, comes with the warning from Read that timing is critical to avoid causing stress to both the mother plant and the new bulb. The best time is mid January to March.

Chipping

Chipping - which can be used to propagate many kinds of bulb - produces more new plants and does not rely on waiting until the mother plant has produced an offset. Once again patience is needed as it can take three to six years before the bulb is capable of flowering. And because chipping involves dividing a bulb you will probably want to have some spare plants on which to practice, before trying to propagate a particularly rare or favourite specimen.

With chipping it is essential that the bulb and especially the basal plate - the round disc underneath the bulb from which the roots appear - looks healthy and undamaged before you start.

'Take your mother bulb and use a sharp knife or scalpel to cut the roots off, taking care not to damage the basal plate,' said Read. 'Next, cut off any shoots and the top part of the neck so that it is flush with the top of the bulb, then peel off any brown papery layers until you are left with a firm white bulb.' Cleanliness is absolutely essential throughout the entire process to prevent the chips becoming contaminated. They will be incubated in a warm place and would be easily overwhelmed by fungi or bacteria, so Read uses methylated spirits to sterilise all her work surfaces and knives.

Cut vertically through the bulb to make four or eight 'chips' or segments, each of which must have part of the basal plate. Aim to get as much basal plate as possible on each segment. Read suggests wearing rubber gloves to handle the bulbs as some people are allergic to the sap of hippeastrums.

Then, still wearing gloves, place each segment into a systemic fungicide for at least twenty minutes, making sure they are thoroughly immersed. You will find a suitable fungicide at your local garden centre and it should be diluted as instructed.

While the chips are soaking, you can prepare the incubation stage. Half fill some clean freezer bags with vermiculite - a sterile medium available from garden centres - and add tepid boiled water. Aim for about one part water to nine parts vermiculite. The chips are then placed in the bagwith the vermiculite. 'It is important not to over-crowd the chips,' Read warns. 'Six or seven chips in each bag is about right.' Shake the bag gently to make sure the chips are immersed in the damp vermiculite, then blow air into the bag and tie the top. If you are chipping several varieties at once, make sure you keep the chips from each separate and make sure the bags are labelled.

The chips can be incubated in a propagator at 25ºC to 27ºC for eight weeks - if you don't have one, an airing cupboard will do just as well. Check the bags every two to three days for mould and if you see any infected chips remove them immediately. If the vermiculite dries out add more tepid boiled water and re-inflate any bags that have gone down. 'Don't blow into the bags if you have a cold,' Read warns from bitter experience, 'it causes a major infection in the chips.'

After two to three days the chips should begin to curl and go pink and, after two weeks, new bulblets will start to form. After eight weeks the bulblets should be ready for potting. Most of the original chip will have broken down, as its food store will have been converted into energy to create the new bulblet.

Remove the bulblets from the bag and wash with tepid water, taking care not to damage any roots. Wipe away excess water and they are ready for planting.

There is no standard compost mix for hippeastrums, but Read points out: 'Excellent drainage is vital. I either use equal parts peat or coir, silver sand and horticultural grit, or just equal parts peat or coir, to sand. I also recently tried equal parts sand and perlite and this gave fantastic root growth.'

Fill a seven-centimetre pot with the chosen potting medium and place the bulblets on the surface. Lightly cover, making sure the nose of the bulblet is still exposed, and then water in with tepid water, taking care to avoid watering directly onto the bulblet as this can cause fungus to develop. Place where the new plant can receive both warmth and light - a window shelf above a radiator is ideal.

For best results keep the compost moist throughout the winter and feed regularly when growth is active. 'Most people consider hippeastrums to be delicate things,' Read remarks, 'But I have always found them to be quite hardy.’

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