Switch on to BULBS

If you’re hoping for drifts of daffodils or beds brimming with bold tulips in spring, then now is the time to plant them, says Monty Don

Planting spring-flowering bulbs in September is good practice – after this the bulbs lose precious growing time. It is also an essential gesture of hope, throwing a lifeline across the gulf of winter to the promise of spring. ‘Bulb’ is a generic word to cover plants that store their next season’s flower within a self-contained capsule that can survive until the following growing season without nourishment or roots. Everything about the flower, all it needs to know to become its full self, is contained within the squat bulb.

True bulbs – such as tulips, alliums and daffodils – are essentially a much reduced stem made from concentric layers of fleshy scales with a protective dry outer layer. Each scale is the base of a leaf or the thick scale leaves that stay below ground. The outer layer is last year’s scales.

There are three distinct forms of bulb. In the most common – such as tulips or alliums – the bulb shrivels and dies after flowering and is renewed from buds at the base of the scales at the point where they join the basal plate. Narcissus bulbs, on the other hand, do continue year on year, producing offsets rather than wholly renewing. This is why you get ever-increasing drifts of daffodils whereas tulips increase more reluctantly, with a loss of vigour – it takes two or three years for most tulip bulbs to flower. The final form is like a Hippeastrum (amaryllis) and has embryonic bulbs for three years ahead within each ‘parent’ bulb.

There are two rules when planting bulbs. The first is to allow at least twice their depth of soil above them and the second to put them pointy end up. But as with all rules, there are exceptions – the imperial fritillary, for example, needs to be fully 1523cm deep and planted on its side, and tulips can be planted just below the surface if they are to be lifted later. However, the guiding rule is that you will do less harm by being too deep than by being too shallow.

Another general rule is that bulbs need good drainage and this is vital for tulips, alliums and Iris reticulata. Mix grit into a general area or container (50:50 grit to potting compost) that they are to be planted in, or add a dollop of grit in every planting hole.

As ever, there are exceptions. Snowdrops and the snake’s head fritillary need damp conditions. Snowdrops are best spread ‘in the green’, which means digging a clump up and dividing it thinly while still in flower or just after. Snowdrops can be planted as bulbs too, but you’ll have a much better success rate this way. When planting bulbs into grass, take out the holes individually for larger bulbs or, for little bulbs like crocus, cut squares of turf, place the bulbs on the soil and put the turf back over the top. The best way to plant larger bulbs in grass so that they make a natural spread is to throw a handful onto the ground and plant them wherever they land.

With containers, pack small bulbs in tightly and use shallow alpine pans that are perfect for crocus, snowdrops, fritillaries, iris, Muscari. Give them some sunshine when dormant. Plant all bulbs as soon as you buy them – the risk of fungal disease and rotting increases the longer they’re stored. I once bought 200 Erythronium bulbs and only 50 survived the two weeks that I’d waited.