Planting tulip bulbs in autumn for a beautiful display next spring is a wonderful thing to do. Whether you are just planning to plant tulips in a pot or if you have a garden to fill, you can get the whole family involved and you’ll have buckets of cut flowers come the spring.
Tulips don’t need to be planted until October/November. They only start putting roots down then and the cold temperatures help to wipe out viral and fungal diseases that lurk in the soil and which may infect the bulbs. Planting late is a traditional means of disease protection.
Dig a trench/hole 20cm deep and, if you garden on heavy soil, cover the base with 5cm of washed sharp sand, horticultural grit, or spent compost. Add a handful of bonemeal to encourage formation of next year’s flowers and mix it into the soil/grit at the base of the hole.
Place the tulip bulbs, pointy end up, about 8cm apart and cover with soil. Again, if you garden on heavy soil you can mix grit at approximately one-third volume with the infill soil. If you’re short of space, cover the bulbs with soil and then add a second layer of bulbs before filling in the hole. There is still enough soil above the bulbs to allow you to over plant without damaging them.
To help you plant your tulips quicker and more easily, you can use a traditional bulb planter, or bulb planting trays
Tips on planting depth
Most gardening books recommend planting tulips at twice the depth of the bulb – at about 8cm in the case of most tulips – but I prefer planting tulip bulbs much deeper. At Perch Hill, they go in about 8cm apart and about 20cm deep. To counteract the poor drainage of my heavy soil at Perch Hill and help prevent the bulbs rotting, I plant them on a grit bed 2in deep, using the finest-gauge gravel from my local builder’s suppliers.
I’ve found planting much deeper has lots of advantages:
Tulips flower more reliably year after year. In the bulb fields of Holland, tulips are planted near the soil surface to encourage them to reproduce. The higher soil encourages reproduction of the bulb, with the mother bulb developing satellites, or bulbils, around her base. Once this has happened, most of her energy goes into these offspring, so the mother bulb will almost certainly not flower the following year, but the bulbils will not be large enough to flower for two or three years after that, resulting in a blind bulb.
If planted deeply, tulips are less likely to try to reproduce and are more likely to flower for year after year. This applies on my heavy clay soil, but is even truer of freely drained sandy soils that warm up to a greater depth in the summer.
(The same goes for growing tulips in pots – this is why you never get a good show from tulips left in containers year after year. If planting in pots, remove the bulbs and plant into the ground as soon as they finish flowering and before the summer. Leave the foliage intact, but remove any deadheads so the tulip doesn’t waste energy trying to make seed.)
Staking isn’t necessary with deep planting. Even huge bulbs, such as Tulip ‘Ivory Floradale’, which can grow to nearly a metre with large, heavy flowers, won’t need any support. The bulb is anchored so deeply in the ground and almost never gets blown over.
Planting in pots
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 2-3cm (1-1½in) apart is about right. The first layer can go as deep as 28-30cm (11-12in), then cover them over with 5cm (2in) of potting compost, before you place the next layer of bulbs. For more info see my video: How to make a bulb lasagne.
It is important to leave the browning foliage on your tulips until every leaf has died right down, usually by early summer. This allows the bulb to store more food and produce flowers the following year. This rule applies across the board with bulbs.
I have found no benefits from digging up tulip bulbs after flowering each year, so as a result I leave them in place. In mid June I rake up all the dead foliage, mulch with 5-8cm of compost or well-rotted manure and over plant with half-hardy flowers or vegetables like courgettes or pumpkins