layering bulbs – how to make a bulb lasagne
To get dense and flowery spring pot displays, you have to try layering bulbs in what the Dutch call a bulb lasagne, layering them up one on top of another. The largest and latest flowering bulbs go in deepest, moving to the smallest and earliest in the top layer. The emergent shoots of the lower layer bulbs just bend round anything they hit sitting over their heads and keep on growing.
Done like this, you need to plant the bulbs slightly further apart than you would in a pot with a single layer so 1 to 11/2 inches apart is the right sort of spacing. The first layer can go as deep as 11-12 inches deep. Then cover them over with a couple of inches of potting compost, before you place the next layer of bulbs.
These combinations involve a two-layer lasagne, but you can push it to three, and branch out from just tulips to crocus, narcissus or hyacinths. I’m experimenting with this triple-decker this year. For my deepest layer I’ve chosen the parrot tulip 'Orange Favourite' with huge, crinkly orange flowers, and the scent of freesias. It’s the last tulip to flower and invaluable for that. In the middle I’ve got a mid-season bulb, good, old, Tulip ‘Prinses Irene’ and I’m also trying out its newly bred sister, ‘Cairo’. This has the same silvery-green handsome leaves but is a deeper, richer colour.
For one pot, my top layer is the famously reliable and handsome Narcissus ‘W.P. Milner’. The foliage appears in January in a sheltered spot and it can flower from February until April if you keep dead-heading. I’ve got another pot with the deliciously scented and delicate flowered March-flowering Narcissus ‘Minnow’ so I can compare which works best.
In my large Longtoms, (16 inches wide and 25 inches deep) I have fifteen bulbs in each layer, so forty five bulbs in the triple-decker, the bottom layer planted at nearly a foot, the middle at 8 inches deep and the top bulbs 4-5 inches below the compost’s surface.
As well as one variety flowering at once in one pot, I’ve been experimenting with mixing sycronized flowerers. I’ve had ‘Prinses Irene’ in my Long Toms mixed up with another couple of early ones - Tulip ‘Havran’ and ‘Couleur Cardinal’. The colours of the three works wonderfully together – I called it my Venetian Tulip Collection - black, deep red and burnt orange, all at their best at the same time.
Last spring I tried another trio of my current favourite tulip ‘Bruine Wimpel’, with ‘Jan Reus’ and ‘Helmar’. Tulip ‘Bruine Wimpel’ is incredible, the inside of its petals the colour of a brandysnap, the outside a mix of copper, chalk and pink and it looked magnificent planted with the deep wine-red ‘Jan Reus’ with a zing of boldness from the deep-red, flashed yellow ‘Helmar’.
This was an almost equal success to my Venetian group, looking good with bright, with healthy, springy foliage through March, topped with flowers for April into May. ‘Havran’ and ‘Jan Reus’ are both the tallest of their groups so they go in the deepest. Then comes ‘Prinses Irene’ , ‘Bruine Wimpel’, ‘Couleur Cardinal’ and ‘Helmar’ all about the same heights so it doesn’t matter which goes in which layer.
Large pot or little, in a group, or just one on its own, autumn is the time to plant your spring-flowering bulb fiesta.
General Bulb Planting Tips
- Bulbs ideally suited to pot growth include Snowdrops, crocus, Iris danfordiae and reticulata, grape hyacinths, scillas, puschkinias, chionodoxas, anemones, hyacinths, narcissus (particularly the small-cupped and species varieties) and tulips (particularly the fosteriana varities (such as ‘Orange Emperor’ and ‘Purissima’), Single Earlies (such as ‘Prinses Irene’, ‘Couleur Cardinal’ and ‘Cairo’), Double Earlies and Triumph tulips (such as ‘Havran’)
- Drainage is key with bulbs, so all pots and containers need one of more holes in the bottom. These holes then need to be covered with crocks – pottery shards or pebbles – to keep the holes from being clogged with earth.
- In pots, you can plant your bulbs closer than you do in the garden. Even so, they shouldn’t touch each other or the sides of the pot.
- If planting just one layer of bulbs, plant at the same depth as you would in the garden – at a depth of twice their height at least (a minimum of 3 inches).
- Water on planting, and regularly in the first weeks when their roots are forming. Don’t let the compost dry out.
- Pots planted with spring-flowering bulbs can tolerate a certain amount of freezing weather, but will need some protection in moderate to severe periods of frost. Cover them with branches or circle the pots with bubble wrap to insulate.