Hyacinth

Light and exposure

Hyacinths like full sun or light partial shade. A spot that gets spring sunshine before nearby trees and shrubs come into leaf suits them perfectly: under a deciduous tree, along a hedge, or against a south or west-facing wall.

For forcing in a pot, keep the bulb somewhere cool and dark for several weeks first, then move it gradually towards the light as soon as the shoots appear. Bringing it into bright light too abruptly produces pale, floppy stems that cannot stand up straight.

Watering

Once planted out in autumn, hyacinths are largely happy with Belgian rainfall and need no particular watering before spring. Water only if autumn is unusually dry, at planting time, to help the roots get established.

In a pot, keep the compost lightly moist without waterlogging it, and always empty the saucer after watering. During indoor forcing, too much water at the bulb stage is by far the main cause of rot, far more common than underwatering.

Soil and repotting

Hyacinths want a light, well-drained soil rather than a rich one. Ordinary garden soil, lightened with a little sand or fine gravel on the heavy clay ground common around Herve, suits them very well.

Drainage is the one non-negotiable point: soil that stays waterlogged all winter rots the bulb before it has even had a chance to grow roots. In a pot, use a bulb compost or a compost-and-sand mix, with a drainage hole at the bottom of the pot as an absolute must.

Temperature and humidity

Hyacinths are fully hardy in our region and cope without any trouble with winter frosts once planted out: the cold is in fact essential, it triggers the process that leads to spring flowering.

For forcing in a pot, this need for cold has to be recreated artificially: the prepared bulb spends six to ten weeks somewhere cool and dark, between 5 and 9 degrees (a cellar, an unheated garage or the salad drawer of the fridge), before being brought gradually up to room temperature to flower.

Pruning and upkeep

Once flowering is over, cut off only the faded flower stem, right down at leaf level, so the plant does not waste energy producing seed. Do not touch the leaves at this stage.

Let the foliage yellow and die back completely on its own, which usually takes six to eight weeks after flowering. This is when the bulb is rebuilding its reserves for the following year: cutting the leaves too early weakens flowering for years to come.

Pests and diseases

Bulb rot, whether bacterial or fungal, is the main problem with hyacinths and it almost always affects bulbs planted in soil that is too wet or poorly drained. A bulb that is soft, foul-smelling or brown-stained at planting time should be discarded without hesitation.

In well-drained soil, hyacinths stay a healthy plant with few disease problems. Slugs sometimes attack the young shoots as they emerge from the ground at the end of winter, a minor nuisance compared with the risk of rot.

Propagation

Propagation is done almost exclusively through offsets, the small secondary bulbs that form naturally around the mother bulb over the years. They are detached when the clump is lifted in summer and replanted straight away, though it usually takes two to three years before they flower in their turn.

Growing from seed is possible but stays a curiosity for a home gardener: it takes five to six years of patience before the first flower, and the seedlings are not always true to the parent variety. It is better to put the effort into dividing well-established clumps instead.

Toxicity

The whole plant is toxic, especially the bulb. If eaten, it causes digestive upset (nausea, vomiting, diarrhoea) in people as well as in dogs and cats. The sap contains calcium oxalate crystals that irritate the skin and can trigger itching or contact dermatitis, particularly when handling bulbs bare-handed during planting or forcing. Wear gloves whenever you handle the bulbs, and keep them out of reach of children and pets.

Month-by-month care calendar

Green Hub tips

• Always wear gloves when handling the bulbs, whether planting or forcing: the sap contains irritant crystals that cause itching for a lot of people.
• Plant in well-drained soil or add sand to the bottom of the hole: a hyacinth bulb that sits in water all winter will almost certainly rot.
• For a Christmas flowering, allow around ten weeks of cold and dark for the bulb before bringing it into the light: the earlier you prepare it, the earlier you get flowers.
• Always let the foliage die back completely after flowering before cutting it off: it is what rebuilds the bulb’s reserves for next year.