Bloom time: What could be more thrilling than tulips running wild in your garden?

For the last month, I have been in heaven, with new tulips opening up around me almost every day. The happiest discovery has been that the small, wild species tulips (botanical tulips, they are sometimes called) have settled in the sloping gravelled area behind a retaining wall and are actually increasing. Having tulips is one thing, but persuading them that they are comfortable enough to multiply is another. Here in Britain, tulips are growing at the very western edge of their preferred habitats. Our job is to jiggle conditions, to help them feel at home.

Most impressive is 'Little Beauty' which flowers while it is still sitting practically on the ground. Each of the bulbs I put in a couple of years ago has built up into a clump producing six or seven rich pink-purple flowers. They open wide to make beautiful upright bowls in the sun. The petals are very pointed, and the outer ones are washed on the back with a dull green. At the centre is an indeterminate white blotch, overlaid with dark, rich blue. The colour is startling and the form very beautiful, as is the case with so many of the species tulips and their offspring. It makes an enchanting garden flower, but being so short, needs its own space in the foreground of a bed, or on a scree, perhaps with stokesia behind or dwarf agapanthus, to fill the space later in summer. It has given a magnificent show, starting in late March and only just finishing.

My tulip stud book, published by the KAVB, the Dutch Bulb Growers' Association, doesn't give the parentage of 'Little Beauty' (bred in 1991) but I'd guess it had the blood of T. humilis from Iran and eastern Turkey running in its veins. In the wild, this is a very variable species and many excellent selections have come from it, including 'Odalisque' and 'Persian Pearl'.

Both those are excellent little magenta-coloured tulips, but they have plain yellow middles, nowhere near as good as the mysterious smudgy blue in the centre of 'Little Beauty'. The middles matter. Perhaps I'm a little obsessive about tulips ("No! Surely not...") but the more you look, the more extraordinary they are. It beats me why anyone bothers with daffodils.

Much paler in tone, a more fragile-looking beauty, is T. bakeri 'Lilac Wonder', now lumbered with a more cumbersome tag, T. saxatilis Bakeri Group 'Lilac Wonder'. This species will always be dear to me because it was the first tulip I ever saw growing in the wild, on the Omalos Plain in Crete. 'Lilac Wonder' is slightly taller than 'Little Beauty' with bright green, slightly shiny leaves standing around the pale mauve-lilac flower. In the middle is a pronounced yellow blotch which covers at least a third of the petals.

'Lilac Wonder' did well in the trials that the Royal Horticultural Society organised at its Wisley garden. Or rather, it started to do well. The trial, set up for a period of three years, had to be abandoned after the second, because of the amount of disease in the ground. I hope one day, it might be possible to start it again, because the point was not to argue endlessly about which was the most beautiful, but to discover which dwarf tulips (species and their kinds) would survive and multiply in a garden without being lifted every season.

The species tulips – 99 different kinds – were planted in blocks of 25 bulbs each. As a rough guide, I am counting as a success any tulip which provided more flowering size bulbs at the end of the trial than it did at the beginning. One block of 'Lilac Wonder' produced 30, another from a different source 34 – not a spectacular increase, but better than the average. We are far more used to tulips dwindling than increasing, but many of the species (and their close relatives) have a toughness and a will to live that is not always found in their bigger cousins.

In a separate part of our garden, I've planted species tulips in a different group of colours: orange, red and fudge brown. The new arrival this year is 'Little Princess', a completely enchanting tulip about 17cm tall, beautifully shaped, its petals closing into a neat point. The colour is difficult to describe, a soft Tudor brick red with the touch of caramel which is what I so like about T. whittallii. Inside, some of the flowers have a very pale smudge at the base. Others have a big black loop shaped blotch, edged in yellow. The stamens are a greenish khaki.

"Well? What do you think?" I asked T. whittallii, as I placed the pots of 'Little Princess' in front of it. But T. whittallii knows it is so far out in front of all other tulips of this kind, it didn't bother to answer. 'Little Princess' did well in the RHS trial though, with 45 flowering size bulbs dug up at the end of the trial period. It came into flower at the beginning of the month and is only just coming to an end now. I'm going to plant it in front of T. whittallii, no matter what it thinks.

"Going to plant" – that sounds back to front at this time of the year, but I first grow most of the species tulips in 18cm black plastic pots. When they are in flower and I can get a true idea of their height and colour, I decide where to put them permanently. Parkers catalogue describes 'Little Princess' as dark orange, which creates quite a different picture from the flower that's been with me over the past month. When the flowers and foliage begin to die down, I dig a hole, and set the whole potful into the ground, disturbing the roots as little as possible. Then I mulch the place with gravel. That reminds me not to put anything else on top of the tulips' heads, but it also helps keep the flowers clean when they push through the ground in spring.

The deepest grooves in the garden though have been worn to the places where T. whittallii grows. Like several other species it's been given a new name – T. orphanidea Whittallii Group, the group thing a way of recognising that in the wild, this can be a very variable flower. But the variability is what I love about tulips and, in any form, T. whittallii is spectacular. Flowering from mid-April into early May, it's about 30cm tall, with neat, pointed petals of burnt orange caramel, very distinct and unusual. The outer petals are flushed with a pale creamy buff on the reverse. A sharp, thin buff line is drawn, as with a ruler, up the midribs of the inner petals. The flower makes a perfect bud with all the petals meeting at a sharp point in the middle. At the base is a smoky, indeterminate blotch, greenish black with a yellow halo, the dark colour drifting slightly up the veins of the petals, like watercolour paint on wet paper. Oh April! Why can't it last for ever?