You only need a space 28cm square to set up a dream of spring. That's the size of my favourite container, an old seed tray made of clay, the kind my great-uncle used before they invented plastic. When he died, I liberated it from his shed along with his rake and hoe. I use them still. The container is barely 8cm deep, but that's plenty enough for the early crocus and gorgeous little iris that flower in early February and March.
You'll need a bit more room to mix up the kind of compost in which I like to grow bulbs in containers. I use a loam compost (John Innes No 3) mixed with 6mm grit. Don't glaze over. It's not half as difficult as preparing sea bass à la something-or-other. Get a bag of the compost and a bag of grit from your garden centre. Set a bucket alongside and with a scoop – any scoop – make up your planting mix with one scoop of grit to two scoops of the loam compost.
The point of this is to make a mix that drains quickly. In the wild, many of these early flowering bulbs grow on the sides of mountains in almost pure shale. They aren't looking for rich food, but they do demand good drainage. In a mix that is permanently soggy, they'll rot.
Any bulb that you buy will already have the beginnings of its flower packed away inside its heart and you have to work hard to prevent that flower from coming out. In a container, where you want the best display possible in the smallest space, you can pack in the bulbs more closely than you would if you were planting in the open ground. In my 28cm square pot, I reckon I can fit 12 or 16 of the small crocus or iris. And even though the container is only 8cm deep, that's enough for these particular bulbs.
Of course, you can use a deeper container, aiming to set the bulbs 8-10cm down from the top. You don't have to fuss about 'crocking' the pot, with bits of broken-up polystyrene, or sharp-edged rubble. Recent research has shown that if you use a fast-draining compost, 'crocking' isn't necessary. After I've planted bulbs in pots or other containers, I always finish off the top with a layer of grit. It stops the blackbirds chucking the compost around, helps the pots drain and keeps the flowers clean as they push through in early spring.
When you've planted the bulbs and watered them, keep the container outside in a cool place and watch for signs of growth. It should not need much extra watering during winter. Just before flowering, you can bring the container inside, but with iris, particularly, it's important not to do this until you can actually see colour in the flower bud. Otherwise, the flowers will refuse to open. If you leave the container outside, the flowers will last much longer.
THE SIX BEST BULBS FOR A SPRING CONTAINER
Crocus sieberi 'Tricolor'; flowers Feb-March; height 5-8cm
This is a sturdily upright crocus, a tricolor triumph originally found on Mount Chelmos in Greece. The flower is outstanding, purple, with a white band separating it from the yellow at the bottom (better than it sounds). Dark bronze runs down the throat into the sheath. It's remarkable for the depth and intensity of its colour. The same markings appear on all six petals, which is perhaps what makes this crocus so striking. Often, the markings show only on the three outer petals. £3.80 for 20 from Avon Bulbs
Crocus tommasinianus 'Roseus'; flowers mid-Feb; height 8cm
A lovely little crocus, wild looking and seemingly fragile (though not). The petals are narrow, the interior colour a tranquil pinkish mauve, the three outer petals washed over on the outside with dove grey. It is one of the pinkest crocus you can grow, an enchanting sight when the sun coaxes out the flower. £3.50 for 10 from Jacques Amand
Crocus 'Vanguard'; flowers late Feb; height 10-12cm
This is bigger than most of the early-flowering crocus, but not as bossy as the large Dutch crocus that flower in March.f It seldom produces more than two flowers from each bulb, so it is not especially prolific but each bloom is beautifully put together. The three outer petals are dove grey on the outside, mauve on the inner, so the flower looks much paler in bud than it does when it opens to show off the startling stigma of burning hot orange. This is a flower with style, selected by JCM Hoog from a batch of bulbs sent to him from Russia, and the variations in the markings make an intriguing sight when it is planted en masse. £5.60 for 10 from Bloms Bulbs
Iris 'Gordon'; flowers early Feb; height 12cm
A very sturdy, upright little iris, with pleasing mid-greyish-blue standards, thin and only very slightly streaked with darker purple. The throat is white, veined with deep purple, and the end of the tongue is the same rich, velvety colour. Down the centre is a distinctive strong orange stripe. Enchanting. And easy. £3.60 for 15 from Avon Bulbs
Iris histrioides 'Lady Beatrix Stanley'; flowers late Jan; height 9cm
This is a gorgeous iris with wide, spoon-shaped, petals. The lid above them divides in two so that each one seems to look at you like an exceptionally alert mouse. Overall, the colour is rich blue, the throats creamy, with a bright yellow beard running down into the centre of the flower. The cream is stippled and streaked with the same blue-purple colour. The flowers smell of violets. This iris demands good drainage, and likes to be cool. Introduced to cultivation c1930, it is named after Lady Beatrix Stanley, the formidable editor of The New Flora and Silva magazine. £5 for 5 from Jacques Amand
Iris 'Katharine Hodgkin'; flowers late Jan; height 8cm
You can take subtlety too far and you may feel that perhaps this iris has. It is a weird colour, navy-blue feathered and spotted on a bluish-cream background, merging into yellow at the throat. But close to, it is extraordinary, so works well in a pot. Subdued and strange in its beauty, it was raised in 1958 by Edward Anderson of Lower Slaughter in Gloucestershire. He was a research chemist, but what he really liked doing was breeding iris like this one. He named it after the wife of his friend, Eliot Hodgkin, who had an amazing collection of rare bulbs at his home near Twyford in Berkshire. £4.40 for 10 from Bloms Bulbs