Can you leave tulips in the ground
It is the winter solstice and after today the light hours start to increase (at last in the Northern Hemisphere) and I am glad. Spring will soon be here and I can’t wait.
It is rather strange that such a common garden plant as the tulip is one that we all accept is almost impossible to grow. Here is a flower that is universally recognised, which is most easily cultivated when it is in the ground for the shortest possible period. It springs to mind because I still have some tulip bulbs to plant. Tulips usually thrive when planted as late as November. I would even leave them till early December at a push. But a last-minute, end-of-season, bargain purchase of tulips only arrived last week and frost and then heavy rain made it impossible to plant them immediately. I just had the chance to rectify this. It is later than I would like but they will be fine – not something I would say about other spring-flowering bulbs.
In the wild, tulips usually grow in areas that are cold in winter and very dry in summer. This is not something I can rely on in this part of the world. With the possible exception of Tulipa sylvestris (above) , which is not common in the trade and not like most tulips (a silly thing to say, I know), there are no tulips native to north-west Europe. There are some purported species from Savoy in south east France and I am growing one of these, T. aximensis (it has many other names) – yes the bulbs just arrived – which is probably some sort of ancient hybrid. Anyway, the origin of the thousands of ‘Dutch’ hybrid tulips, as opposed to those that can be neatly linked with any specific species, is unknown. But we can bet that they come from dry summer areas so they are best lifted every year and the bulbs kept dry in summer.
There are other reasons for their strange needs. Unlike most bulbs, tulip bulbs are ‘consumed’ as they grow and replaced by one or more new bulbs. Often these are not big enough to bloom but, after a few more years they will flower. But a crowd of bulbs will not permit any one to reach maturity. As a rule, if bulbs are planted too near the surface, they break up into many smaller bulbs. If planted deeply they break up less. There is a logic to this.
Below: These tulips have been in this pot for three years, among foliage plants
In the wild, tulip seeds obviously drop onto the soil surface and grow. So how does a tulip bulb get 20cm deep in the soil without the help of a gardener? Tulip bulbs, in common with other bulbs, produce special contractile roots. These grow vertically into the soil and attach at the base. Then they shrink and pull the bulb down. It is obviously easier to pull down small bulbs than one large one so if a tulip is too near the surface it breaks up into small bulbils and these can more easily pull themselves down into the soil. But, for gardeners, we don’t want lots of small bulbs, we want a few, large, flowering bulbs.
In addition, tulips produce ‘droppers’ which are bulbs on stems that grow into the soil, forming bulbs much deeper in the soil.
As a general rule, if you want to plant tulips and for them to be permanent you have to consider several things.
Firstly, the soil should be well-drained and light, the bulbs in a sunny spot and, ideally, baked in summer. The latter is not essential but it helps. Tulips will grow in heavy soils but they must be freely drained.
Below: ‘Pink Wave’ is a Parrot tulip that is a sport of ‘Green Wave’, a very reliable Viridiflora tulip. I find that both are reliably perennial. They also are among the latest to bloom.
Some species are better than others and many species are quite good. I find that T. kaufmanniana and T. greigii types do well, as well as T. praestans (top pic – growing after many years after planting, hence the comparative lack of flowers compared to leaves) and T. clusiana. Among the hybrids, I find that most late-flowering kinds do well, especially the Viridiflora (below) and Lily-flowered kinds. But many Darwin Hybrid and Triumph tulips last for years too. I find that the early single and early doubles are the least reliable. I tried the fiendishly expensive ‘Ice Cream’ tulips last year and they didn’t make good bulbs but I was not that impressed with the flowers anyway.
Deep planting is essential and, for most – except the species that have small bulbs – planting at least 20cm deep is best. This deep planting not only helps prevent the bulbs splitting too much, it also prevents, or at least reduces, damage to the bulbs through subsequent cultivation in the border.
In this garden I grow most of my tulips in pots or raised beds. The best (or most expensive) go in pots. I lift them and sort them and keep the largest for replanting. I do have a raised bed as a nursery bed to grow on some too. If (when) I have an excess, which will obviously be a vigorous kind, I plant them in the beds to see how they will do.
The tulips in this pot are in their second year. They were allowed to die back, lifted and dried and the largest bulbs replanted to give this display.
The Biking Gardener 
The more popular sorts of tulips need more chill than they experience here. However, I am aware of a coastal garden, which gets less chill than mine, in which tulips have bloomed for a few years. It sort of makes me wonder if I am doing something wrong.
T. sylvestris has grown here for many years but has not increased to any extent. T. acuminata does better, increasing pleasantly. T. bakeri ‘Lilac Wonder’ grows like the clappers and is invasive while T. sprengeri also grows very well, spreading strongly by self-seeding. The ornamental tulips are purely for annual pot display here.
It is good that you have success with those. I have not had the species in the ground long enough here to judge but when i was at Myddelton House T. sprengeri was widespread. It had survived decades of neglect in beds that were overgrown, largely with Smyrnium perfoliatum. The soil was very gravelly and dry and this prevented the establishment of heavy-leaved shrubs. But as areas were cleared and the tulips, and other bulbs, got more light, they gained strength and began blooming. it is obviously longlived and tough and can seed freely where happy.
Brilliant post, very informative!