Tulips

Ask a group of gardeners to list the top ten spring-flowering bulbs and the chances are that they’ll all put tulips near the top of their lists, probably just below daffodils. So I don’t really need to describe tulips, do I? Everyone knows them and most of us love them, but though beautiful and spectacular, they’re not always the easiest bulbs to grow well.Gardeners in mild areas often find that their tulips’ flowering is limited because their winters lack the cold needed to adequately chill the bulbs, while aphids, viral and fungal diseases are problems everywhere. However, with a little care and attention, tulips can be very rewarding and productive.HistoryTulips have been in cultivation for a long time. Exactly how long is not known. We know for sure that they first reached temperate European gardens in 1554, but the earliest mention of them in a gardening context is in a Persian poem of 1258, so we can assume they had been cultivated in their native lands for some time before then.Even the name tulip has dubious origins. The Persian and Turkish name for the bulbs was ‘lale’, and it seems likely that the Belgian diplomat, Ogier de Busbecq’ who sent the first bulbs and seeds to Vienna simply corrupted the Turkish word for turban (tülbent) to tulipam as a description of the shape of the flowers.What is certain is that within 75 years of their arrival in Europe they were so widespread and intensively cultivated that John Parkinson in his 1629 book Paradisus was able to list 140 cultivars. And it was only five years later that the Dutch craze for tulips, known as ‘Tulipomania’, began.Tulipomania was a speculators’ promotion based on getting rich quick by selling desirable tulip varieties to those who would breed them and then sell the progeny. Think ‘1987 crash’, phone cards or ostriches and you’ve got a pretty a good idea of what it was all about. Needless to say the bubble burst and many people lost their fortunes. But for the brief period between 1634 and 1637 tulip speculation was all the rage and, like all boom and bust cycles, those who knew when to get out did well. Records discovered in a demolished Brussels house revealed that it had been built with proceeds from the sale of just three tulip bulbs.Even though their height of financial fame didn’t last, tulips remained popular and continue to be grown in large numbers, particularly in Holland. However, instead of being cultivated for the production of bulbs, the vast majority are now grown to satisfy the demands of florists. Tulips, whether forced into bloom under lights or grown outdoors, last remarkably well when cut and have always been popular cut flowers.Tulips are also extensively cultivated by botanic and show gardens, which often plant out massed beds for spring displays. Bulb growers often have large areas planted out for productions and these growing-on fields can be a spectacular sight.Tulip divisionsHowever they’re cultivated, tulips are beautiful plants, but with so many that are so similar to one another they’re difficult to classify. So, in common with other genera, such as lilies and daffodils, that have been extensively hybridised and developed, tulips are divided into several groups or divisions based on parentage, flower type and flowering season.TypesApart from the obviously very distinct types, such as the frilly Parrot tulips and the distinctly different species, differentiating between these groups is something of a minefield for the everyday gardener. Unless you’re a real tulip buff, in which case you probably know all the details, it’s probably best just to stick to broadly defined flowering times (early, mid and late) and buy your tulips on the basis of the photographs in the nurseries and garden centres. But for those who need to know a little more, here are the main types.EarlyThe single-flowered early tulips are 15–40cm tall and occur in a wide range of colours, including bicolours, striped and otherwise marked. They include some of the oldest tulips still cultivated, with some dating back to the 1700s. The doubles tend to be self-coloured or more simply marked and are at the taller end of the size range, around 30–40cm tall. They tend be rather open, frilly-petalled doubles rather than rosebud or peony-form in style.Mid-seasonSimilar to the Early Tulips, the Mid-season group includes two types: the 40–50cm tall Triumph hybrids and the 50–70cm tall Darwin hybrids. Triumphs, which now include many of the earlier Mendel tulips, were developed in the years between the two world wars. They occur in a huge range of colours and new hybrids are still being developed. Darwin hybrids date from the early 1940s and are generally robust plants. They don’t cover quite the colour range of the Triumphs but make up for that with vigour and clarity of colour. Darwin hybrid tulips are everyone’s idea of what a tulip should look like. They’re the style most often used for mass bedding.LateIn addition to the typical single and double forms (peony-flowered), this group includes five fancy styles: lily-flowered, with long pointed petals; Fringed, with finely cut or fimbriated petal edges; Viridiflora, with flowers in pastel tones marked and flared with green; Rembrandt, in which the flower patterns are caused by the tulip breaking virus; and Parrot, a selection of sports in which the petal edges are deeply cut and sometimes recurved.All of these flower types occur in a wide range of colours. The very darkest-flowered or “black” tulips are to be found in the late-flowering group. Many of these fancier blooms appeal for their novelty value and are grown as single specimens, either in the garden in mixed plantings or in containers.Botanicals and SpeciesThis catch-all category encompasses all the wild species, their cultivars and a few stray garden forms that may or may not be hybrids.The wild species, of which there are around 100, are of course an enormously variable group. They include the tiny flowers of T. biflora, the beautiful yellow and creamy white T. tarda, the strangely shaped, narrow, yellow and red petals of T. acuminata and even a few stoloniferous species. Some of the species, particularly T. eichleri and T. batalinii, occur in several cultivars.Three selections of species hybrids are large enough to be recognised as distinct groups. They are: Kaufmanniana, usually less than 30cm tall with flowers in yellow, orange, red or combinations of theses colours; Fosteriana, 25–50cm tall with cream, yellow, orange or red flowers often with a contrasting throat colour; and Greigii, usually less than 25cm tall with purple-mottled foliage and flowers in much the same colour range as the Fosterianas.Climatic requirementsAs with virtually all plants, success with tulips is largely a matter of replicating as close as possible their natural growing conditions. Tulips are native to southern Europe, western and central Asia and North Africa, and most come from areas with a cool, wet winter and a distinct spring season that is followed by a dry summer.Although some of the species, notably those from the Mediterranean region, will thrive in mild climates, most tulips need a prolonged period of winter cold. This doesn’t have to be severe, but unless the soil temperature falls below 8–10°C during their slow winter development, tulips may flower on very short stems at near ground level or the buds may be aborted entirely. The soil temperature at planting time is also important because if it remains at over 14°C for a prolonged period, the bulbs may start into leaf growth but abort their flower buds.If you live in an area with mild autumn weather or where the soil temperature tends to stay above 10°C year round, you may have to chill your tulip bulbs in a refrigerator or buy new stocks each year. Keeping the bulbs in the vegetable compartment of your refrigerator at 2–5°C for around 8 weeks prior to planting should be adequate. If you have to chill the bulbs make sure they’re planted at the coldest time of the year, usually around late June to mid July. That means putting them in the refrigerator from late autumn onwards.PlantingTulips should be planted from late autumn to early winter in a sunny position with well-drained soil that is preferably very slightly alkaline (pH 7.0–7.5). Most soil types can support tulips, but it’s important that the soil should deeply cultivated and well-drained in order to keep the bulbs rot-free and too allow the roots to spread as much as possible.They generally do best when planted fairly deeply, say around 12–15cm. If you intend for the bulbs to remain in the ground and naturalise, plant even deeper, down to 30cm. Shallow planting will often cause the foliage to appear too early, making it prone to winter damage, and the flower stems will not be as strong and droop-resistant as those of more deeply planted bulbs. Planted at such depths, it’s not uncommon for the roots to reach as far down as 60cm, at which level they can obtain a steady supply of minerals from the subsoil, in turn further improving the vigour of the bulbs.Deep planting also ensures a more stable soil temperature, which means that the bulbs are not much affected by any unusually hot or cold conditions that might prevail for a day or so during winter or early spring.FloweringTulips are very sensitive to being damaged as they emerge from the soil and as their flower buds develop and expand. Take great care when cultivating around the bulbs because any small nick or scrape on the developing foliage will enlarge as the leaves expand and may form a hole or leave an unsightly scar. The flower buds are sensitive to sudden changes in temperature and soil moisture, and if stressed too much will simply cease developing and abort.Provided they are fed well and receive plenty of sunlight, tulips should be largely self-supporting. However, it often occurs that the flower stems are rather floppy and inclined to droop. Planting the bulbs en-masse so that they help support one another is one solution, but sometimes you may need to use small bamboo canes to support the longest flower stems. This is best done early, before the flowers open, droop and become mud spattered, and of course take care not to spear any bulbs with a bamboo cane.Watch the flowers for signs of aphids. Inside the flower heads is one of the first places these pests are found.Once the flowers are spent, remove their heads to prevent any pests from sheltering within. Any flowers that have shown signs of viruses should be burnt.PestsBecause they often completely smother the flowers and buds, aphids are the pest that are most easily noticed, but more insidious are bulb mites, which attack the bulbs and multiply within them, causing the bulbs to become soft and eventually rotten.Dipping the bulbs in insecticide before planting will ensure they start life clean and healthy. A dusting of soil insecticide about the time the foliage starts to really make a growth spurt will keep them that way.Aphids often occur in such heavy infestations that they can be very debilitating. They not only suck the sap of the tulips and drain their energy, but dust and debris will stick to the aphids’ honeydew secretions making the foliage unsightly. Fortunately, aphids are not very vigorous creatures and are easily controlled even with very mild insecticides and soap- or detergent-based sprays. However, they certainly have the weight of numbers and breeding potential on their side, so constant vigilance is essential.Both bulb mites and aphids spread diseases and should be controlled as much for that reason as for the direct damage they may cause.DiseasesTulip fire (Botrytis tulipae) is a fungal disease that can attack any part of the plant, but which is most readily observable when the foliage develops a greyish-white ‘ashen’ look. It usually occurs when the bulbs are stressed, such as when hit by late frosts or during periods of unusually warm humid weather.The fungal spores spread rapidly and are a major threat where tulips are grown en masse, such as in commercial flower or bulb beds. The disease is not always well controlled by fungicides and the only sure method of control is the rapid removal and burning of infected stocks. It’s also advisable to avoid planting tulips in an infected area for at least two years after an outbreak.The best known and most significant viral disease of tulips is tulip breaking virus or TBV. It may in fact be a combination of several diseases that cause splashed, spotted or striped markings known as ‘broken’ colours. These brilliantly marked tulips, known as Rembrandts, are certainly spectacular but the virus eventually weakens them and they gradually lose vigour and die.Once offered for sale, such plants are no longer deliberately bred. Although their striking colouration may tempt you to keep any infected tulips, remember that plant viruses are virtually incurable and that the disease could spread.The bulbs are also prone to a soft rot that causes them to decay in the ground. Although it’s discouraging to find that your bulbs have rotted before they’ve even emerged, this isn’t really that serious a problem. It isn’t spread easily and usually only develops if the drainage is poor. Dipping the bulbs in a fungicide before planting and providing good drainage will largely prevent rot developing.LiftingOnce the bulbs have sprouted, flowered and died back, you need to consider their summer requirements. Tulips generally prefer warm, dry summer conditions and many of the same areas that are too mild in the winter are often too damp in the summer to ensure the bulbs’ continuing good health. Even in dry-summer areas it’s usually best to lift the bulbs so that they aren’t damaged by being cultivated around or through competition with other plants.The bulbs planted in the winter are spent during the flowering process and are replaced by a new flowering sized bulb and one or more smaller ‘daughter’ bulbs. So when you come to lift the bulbs you should notice an increase in their number.The lifted bulbs should be cleaned of soil and other debris, dusted with flowers of sulphur to keep them fungus-free and stored dry at around 15–21°C. Heavy brown paper bags are best for storage as they allow the bulbs to breathe and because they will quickly reveal if any moisture is present.The bulbs will start to show foliage in the late autumn and in suitable areas may be planted as soon as the soil is cool enough.In areas with an appropriately cool winter climate, tulip bulbs can be left in the ground all year. In warmer and wetter areas take care to select species tulips from mild climates if you want to leave the bulbs untouched. Good choices for mild gardens include T. bakeri, T. clusiana, T. kaufmanniana, T. cretica, T. sylvestris and T. saxatilis. Tulipa sylvestris and T. sprengeri are particularly tolerant of damp summer conditions.

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