Hyacinth Summer Dormancy: Lifting, Drying and Storing Bulbs

What dormancy actually is

From late spring, when the leaves yellow, until early autumn, when roots start moving again, a hyacinth is a dry storage organ doing very little. It is not dead and it is not growing. Inside it, over that summer, the flower bud for the next spring is being differentiated out of the food the leaves put in. That process happens in warm, dry conditions, which is why the treatment for summer is warmth and dryness rather than care.

Left in the border, they manage this on their own provided the ground drains. The single thing that kills a dormant hyacinth is water sitting around the basal plate in warm soil, which turns the bulb to soft brown slime within a fortnight. Cold does not kill them; hyacinths are hardy well below freezing when dry and dormant. Wet warmth does.

This is why hyacinths are a poor choice for a bed that gets summer irrigation, and why they do well against a wall, in raised ground, or under a deciduous shrub that pulls water out of the soil all summer. If you have a bed you water heavily in summer, plan on lifting the bulbs rather than fighting it.

Leaving them in the ground

In free-draining soil the simplest approach is the best one. Once the foliage has pulled away, stop watering that patch entirely and let it bake. Do not mulch over the top with anything that holds moisture; a thick wet mulch in summer does exactly what you are trying to avoid.

Mark the position clearly. Hyacinths leave no trace above ground for four months and are routinely destroyed by a fork going in for summer planting. A short cane, a permanent label or a note in your records against a fixed point all work; memory does not.

You can plant shallow-rooted summer annuals over a dormant hyacinth group, and it works well as long as you accept that anything you plant there will need very little water. Deep-rooted or thirsty summer plants over a hyacinth group is a slow way to lose the bulbs.

In climates with wet summers, or on clay that stays cold and damp, lifting is the honest answer. There is no soil amendment that turns a permanently wet bed into a place hyacinths survive summer.

Hyacinth bulbs are toxic and rodents will not touch them, so unlike tulips they need no protection from mice or voles while dormant. Squirrels will occasionally dig one up, sniff it and abandon it on the surface; push it back down rather than leaving it dry on top of the soil.

Lifting, drying and storing

Lift once the leaves have fully yellowed and pull away with a light tug, not before. A bulb lifted while the leaves are still green has not finished loading itself and will flower badly next year regardless of how well you store it.

1. Fork up the whole clump Work six inches (15 cm) outside the old leaf positions and lever up rather than digging in from directly above. Bulbs pull themselves deeper over the years and sit further down than you expect.
2. Clean, but do not wash Rub off loose soil with your fingers, wearing gloves. Do not wash bulbs under a tap; water in the scales is exactly what starts storage rot. Leave the papery tunic on, and leave adhering dry soil alone.
3. Cure for a week Spread them in a single layer on a tray in a shaded, airy, dry place at around 70F (21C). One week firms the skin and dries the basal plate. Never dry them in direct sun, which scorches the scales.
4. Sort and discard ruthlessly Squeeze every bulb at the base. Anything soft, moldy, hollow-sounding or weeping goes in the bin, not the compost pile. One rotting bulb in a tray will spoil the ones touching it over the course of a summer.
5. Store dry, dark and airy Paper bags, net bags or open trays in a shed or garage at 60 to 65F (16 to 18C). Never sealed plastic, never a damp cellar. Check once a month and pull out anything that has softened.

Bulbs that have been forced indoors

A bulb that was forced on a glass in water alone is finished. It flowered on stored food with nothing to replace it, and the roots in water never fed it back. Compost it without guilt. Nobody gets a second season out of a water-forced hyacinth, and trying is a year of pot space wasted.

A bulb forced in compost is a different case. Keep it watered and fed with a potassium feed after flowering, keep it in the light until the leaves yellow, then dry it off, store it as above and plant it in the garden in autumn. It will not force again, and it will give a thin, short spike its first garden spring, but by the second or third year it settles into a perfectly good loose garden hyacinth.

The reason a forced bulb cannot be forced again is that the controlled cold, warmth and feeding schedule that built that dense truss took a full growing season in a grower's field. Your windowsill did not rebuild it. Treat forced bulbs as a one-off display and a free garden plant afterwards, and you will not be disappointed.

Keep a note of which bulbs came out of pots and which came from the garden when you store them, because a year later you will not be able to tell them apart, and a group of ex-forced bulbs flowering weakly in their first garden spring is easy to misread as a drainage problem.

Records that pay off next spring

Write down the lifting date, the number of bulbs lifted, how many you discarded as soft, and where they are stored. The discard count is the useful number: if you lose a fifth of a group every summer, the bed is too wet and no amount of careful storage will fix that.

Also record the storage location and temperature. Bulbs stored in a garage that gets hot under a metal roof in high summer come out looking fine and flower poorly, and without the note you would never connect the two. A thermometer left in the storage spot for one summer tells you whether that spot is usable for good.