Hyacinths carry more scent than anything else in the spring garden, and they are the easiest of the spring bulbs to overlook outdoors. This guide covers where to put them, how deep they go, growing them in pots, and how to have them flowering in the house at Christmas.
WHY GROW THEM OUTSIDE
Everyone has become so familiar with hyacinths grown in pots that their use in the garden can often be overlooked. Which is a pity. They are ideal for bedding, being relatively short they are perfect for the front of borders and indeed for containers, and a group by the door will do more for a spring garden than almost anything else you could put there.
Plant enough of them. They do not drift and they do not mingle the way a smaller bulb will, so two dotted down a border simply read as a mistake, whereas nine or a dozen of a single colour in one block reads as a decision somebody made on purpose. That is the whole difference. Nothing else about them is difficult.
That is how they are used at the Keukenhof, in blocks, and anyone who has walked round it will have noticed how much more freely the Dutch plant them than we do here. We could stand to copy them. And if it is blue you want in a spring border, nothing else comes close for depth of colour.
CHOOSING YOUR BULBS
There are two garden grades and the difference is size rather than quality. The bigger bulb throws a fatter spike, which tells when the flower is going to be looked at closely in a pot or a bowl on the table, while the smaller one costs less and is what to buy when you are putting fifty of them down the front of a border. Neither smells any different.
WHEN TO PLANT
Put them in after the daffodils and before the tulips. Late September into October, for most gardens, though soil temperature decides it rather than the calendar and what you want is ground that has cooled without going cold and wet. If the autumn is running warm and dry, get the border ready and hold the bulbs back a fortnight. Nothing is lost by waiting.
They do not have to go in the day they arrive. Open the box, get the packaging off them, and keep them somewhere cool and dry and airy until you are ready. What matters once they are in the ground is root, and root comes from a cool temperature and even moisture in those first few weeks. Everything else follows from that.
HOW DEEP TO PLANT
Depth matters more here than people expect. Plant them 10 to 15cm deep (4 to 6 inches), which comes out at two to three times the depth of the bulb itself, going deeper on heavy soil and shallower on light, because a hyacinth set shallow will split and the spring after you get several thin stems where you wanted one good one. Go deeper if in doubt.
Work the soil over to the full depth before you start rather than digging each hole as you come to it. Outline the area, set the bulbs out on the surface where you want them, then plant the lot with a trowel. It is far quicker that way and the spacing comes out better, which is the part you notice in April.
Spend and Save
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IN THE BORDER
They want a rich, well drained soil and a sunny aspect, and that really is most of the battle. Dappled shade is worth knowing about too, because it will not stop them flowering and it keeps the flowers fresh for longer than full sun does. What they will not tolerate is a permanently damp, sunless corner.
Space them about 10cm apart (4 inches). Any closer and the clumps run into one another within two seasons, which is the point at which the flowers start coming smaller, and left where they are a border hyacinth will otherwise carry on happily for three or four years before it wants lifting and dividing. They ask very little.
IN POTS AND CONTAINERS
Pots suit them, but use a good soil based compost rather than a light multipurpose one and put them somewhere sunny. Balance the bulb to the pot as well, since a tall spike in a shallow bowl looks wrong and goes over in the first wind, and the pot should never end up being the star of the show.
The real mistake is letting them go dry. They need watering through dry spells in the growing season, and that includes the weeks before there is anything at all to see above the compost, which is exactly when it is easiest to forget. Skip it and the heads come up short and shrivelled. If the pot stands outside all winter, raise it on feet so it drains.
CHRISTMAS HYACINTHS, WITHOUT THE AID OF A GREENHOUSE
That phrase comes straight off our own catalogue pages of the 1970s, when bulbs to flower on Christmas Day without the aid of a greenhouse were a fixture of the autumn list. It is a good deal less common now, which is a pity, because it is not difficult and the result beats anything you can buy already in flower.
A prepared hyacinth is not the same bulb as the one you put in the border. The flower inside has been brought on early under controlled treatment, which is the whole reason it opens in December rather than April, and that treatment is not finished until early September, so anything offered to you before then has not had it. Ordinary garden hyacinths will not do this.
You need three things and none of them is a greenhouse. Prepared bulbs, bulb fibre, and somewhere cold and dark to put them for about ten weeks. Fibre rather than potting compost, because the bowls these go into usually have no drainage holes at all, and the charcoal in it is there to keep the water sweet.
Then the calendar takes over. Prepared bulbs want something in the order of ten weeks in the cold and the dark before they will do anything at all, which is the whole reason the potting date matters as much as it does, and why a fortnight of delay in September turns Christmas hyacinths into January ones. Lovely. Not the point.
The soft blue, and the classic
Pure white, best in a plain bowl
Deep carmine, the strongest colour
Soft pink, gentler on the eye
Pot them by the end of September or the first days of October, using bulb fibre, and leave the top quarter of each bulb standing proud of the surface. Do not firm it down hard. As the roots go out they will lift a tightly potted bulb straight back up out of the fibre, which is a nuisance to put right once it starts.
Then they want a cold dark spell to root. A cold frame does it, or the foot of a north facing wall with soil heaped over the bowls, or a cellar or a cupboard, and the only real rule is that they must never dry out while they are in there. Ten weeks is what you are aiming for.
Around the first of December bring them into a dark room at roughly 20 degrees and leave them alone until the bud stands six to eight centimetres clear of the neck of the bulb. Only then do they go somewhere sunny to open. Bring them up too soon and the flower opens down in the neck on a stem too short to be worth looking at, and it never really recovers.
Keep them moist the whole way through. That is the part most people get wrong. And keep them well away from the fruit bowl, because ripening fruit gives off ethylene gas, which does us no harm at all but will quietly stop a hyacinth flowering altogether and there is no way back from it once it has happened.
A glass will do it too, with no compost at all. Fill it so the water sits a few millimetres below the base of the bulb rather than touching it, and the roots will find their own way down into it over the following weeks, which is worth watching at least once. Top it up to that same level. Half as tall as the finished flower, or it goes over.
AFTER FLOWERING
Take the spike off as soon as the bells go over. There is no sense letting the plant put a month of effort into setting seed you will never sow, and the sooner the flower stem comes away the sooner everything the bulb has goes back into itself instead. Leave the leaves alone though.
That part matters more than anything else on this page. The foliage looks scruffy for six to eight weeks and every instinct says tidy it, but the bulb is drawing the whole of that leaf back down into itself the entire time, building the flower you will get next spring before this one has finished. Cut it early and you get a smaller flower. It really is that direct.
Do not feed them the moment they finish. It is the obvious thing to reach for and it is wrong, because a bulb that is about to go dormant sits wet and fed and rots. Feed them instead when the noses come through in spring, and again in early autumn. The autumn one is the feed that counts.
Keep the water going while the leaves are still green. In a dry spring that is easy to forget, since the flower is over and the plant looks finished, but it is still working and a bulb that dries out now is a poor flower in nine months time. Once the foliage has yellowed, stop.
In the border, leave them where they are. Three or four years is the usual run before a clump gets crowded enough that the flowers start coming smaller, and that is the point to lift it, pull the offsets apart and replant them further out. Any autumn will do for the job.
A forced hyacinth is best treated as one season indoors. Plant it out in the garden afterwards and it will usually flower again, though never quite as heavily as it did that first Christmas.
WHAT CAN GO WRONG
Shallow planting is the common fault and splitting is how it shows up. Bark is the other one. A decorative bark mulch over the border looks tidy enough in November, but it keeps the warmth off the bulbs later in the year and the flowers get weaker every season until you wonder what happened to them.
Water the pots before there is anything to see. A dry spring gives you stunted heads and you will not know why, because the flower was over and the plant looked finished long before the damage was done. Avoid a corner that never dries out, too. Shallow planting, bark, water. That is the whole list.
PLANT THESE WITH YOUR HYACINTHS
Hyacinths sit well with almost anything that flowers at the same time. Muscari underneath them, dwarf daffodils alongside, early tulips coming through behind.
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