These are intended as some basic notes about the cultivation of
Cyclamen. It is difficult to generalise for two reasons.
1. Each species is slightly different, and some comments relating to this will be found as appropriate on the individual species pages.
2. Whilst this is written in Hampshire in southern England, it is intended for a world-wide audience. Here in the UK, we are not so used to the zoning system for rating hardiness. Whilst zones have been used in these pages, they do not tell the whole story, since snow cover which exists in many countries allows plants to survive far lower temperatures than they could without it.
Notwithstanding, lessons can be learnt from the conditions in which the different species grow in the wild. As essentially Mediterranean plants, they are generally dormant during the summer months, come into growth as cooler, damper weather starts, flower in autumn, winter or spring, and go dormant as the summer becomes warm. There are exceptions to this. Cyclamen repandum & its allies flower through late spring to early summer. Cyclamen purpurascens is essentially a woodland plant which, provided it receives adequate shade, will flower through July, August, September and often into October or even later.
Whilst several species are extremely hardy, none of them are at their happiest in frosty conditions and they react in different ways. Whilst C. hederifolium and C. coum will go limp and their leaves will darken almost to black, they will recover, especially if allowed to do so slowly, out of direct sunlight. Other species may have their leaves 'cut back' by frost but the tuber will survive provided not planted at the surface.
At the other extreme, Cyclamen will survive considerable heat when dormant though few species appreciate a severe baking.
Cyclamen are very tolerant of diverse soil types and are not concerned too much with the pH, although they prefer a slightly alkaline soil. However, whether they prefer woodland conditions or or a more open environment it is important to ensure that the drainage is good as excessive moisture can cause the tubers to rot. Since Cyclamen are tolerant of root competition they often grow well at the base of trees and shrubs which not only provide some shelter from harsh winds, but help to remove excessive moisture. All species appreciate extra grit being incorporated into the soil, whilst the woodland species (C. purpurascens, C. repandum, C. creticum) enjoy either leaf litter or composted bark. Other species such as C. graecum which in the wild grow either in rocky areas or under scrub or isolated coniferous trees, respond well to decayed pine needle litter.
The majority of Cyclamen species should be planted with the top of the tuber at, or just below the soil surface. A good option is to have the tuber just at the surface but with a covering of grit or gravel 1 to 2 inches (2.5cm - 5 cm) deep. The less hardy species are better planted slightly deeper, maybe between 3 and 6 inches (7.5cm - 15cm) deep, depending on the species and size of tuber.
Ranking the species in order of suitability for growing outside:
1. C. hederifolium
2. C. purpurascens, coum and repandum
3. C. cilicium, pseudibericum, trochopteranthum, mirabile and parviflorum
4. C. cyprium, graecum, creticum and intaminatum
5. C. libanoticum
C. parviflorum may be ranked alongside C. purpurascens,
coum and repandum in terms of hardiness, although in the wild it is
used to surviving very low temperatures under snow cover, not when subjected to
severe freezing without this protection. Although C. parviflorum
frequently flowers in snow melt-water, it is very intolerant of standing
C. intaminatum probably ranks alongside C. cilicium for hardiness, but is a very small plant and is easily lost in the open ground.
C. graecum was long considered unsuitable for growing out of doors. However it has proved to be more resistant to frost than had been thought, and its tactile roots pull the tuber deeper under the surface.
Many Cyclamen enthusiasts grow their plants in pots, and certainly for the purposes of showing there is no better way as the foliage will be maintained in a better condition. The exception to this is Cyclamen repandum ssp. repandum, which many growers find difficult to grow well in pots, where it rarely thrives. With the tender species the only alternative to pot growing would be to plant out in some sort of raised bed in a frost-free glasshouse.
A generally acceptable compost would be well drained, but incorporate a proportion of organic matter for a degree of water retention. Proprietary soil-less composts based on peat, coir or composted bark are generally not very satisfactory unless extra grit is added in a proportion of about 2 parts compost to 1 part of grit. The exception to this is the use of composted bark based compost used to grow woodland species - in which case the plants can grow very well given adequate but not excessive watering. Particular problems can be experienced with peat based composts following a period of summer dormancy, when it can be very difficult to persuade the compost to take up water.
Although many serious growers have their own specific recipe for compost, a good general mix can be made by mixing together 3 parts John Innes No.3 compost with 2 parts sharp potting grit, and either 2 parts decayed leaf litter (leafmould) or 1 part peat. John Innes Compost is a standard loam based compost available in the United Kingdom, which has added nutrients according to a strict formula, in increasing proportions from J.I. 1, through J.I. 2 to J.I. 3. In countries where this is not available, sterilised loam should be used with the addition of a handful of bonemeal to a large bucket of compost. Cyclamen should not be over fed as this encourages leaf growth at the expense of flowers and can lead to a 'cabbage like' appearance especially with species such as C. persicum.
All species can be planted with the tuber at soil level, but then covered with a layer of grit about 1/2 inch (just over 1cm) deep. Some growers find it more satisfactory to plant the woodland species slightly deeper, and C. graecum may use it's tactile roots to pull itself deeper in the pot.
Different species produce root growth from different parts of the tuber, and there is a case for planting the top-rooting species such as C. hederifolium slightly deeper also.
Most species of Cyclamen will tolerate being grown in a cold glasshouse/alpine house here in southern England. The degree of tolerance varies enormously and in some species is limited to the foliage being destroyed whilst the tuber survives provided the compost is on the dry side. In these circumstances, unless there is no alternative, for practical purposes it is more satisfactory to consider these plants not to be frost hardy, and for them to be kept just frost free. A guide to this will be found under the individual species listings.
It should be noted that Cyclamen rohlfsianum is the least hardy and will not tolerate any frost.
Use of plastic or clay pots is a matter of choice. Growers who use
exclusively clay pots, often combine this with growing plants with the pots
plunged to the rim in sand in order to facilitate maintenance of a moist but
not over-wet compost. Plunging in sand also minimises the effects of frost on
Cyclamen tubers as the compost is less prone to freezing. Plunging plastic pots
is of little benefit from a watering point of view, and may in fact be
detrimental as it can negate the free draining nature of the compost.
An alternative is to stand pots on a layer of gravel or sand as this facilitates drainage whilst helping to maintain moisture at the roots.
Cyclamen prefer to receive a good soaking, and then to be allowed to dry out to some extent, before again receiving a good soaking. Generally, the woodland species require a more constant supply of moisture in order to thrive, although even they will not tolerate becoming waterlogged for any period of time without rot developing. Some growers believe that it is significantly better to always water pots from below, by standing them in water. Certainly this keeps the flowers in better condition and reduces the risk of botrytis, however, it is not a requirement and watering from above can be equally acceptable.
Repotting should be carried out during the dormant period, but is best done after the roots have started into growth again in late July and through August. Cyclamen purpurascens flowers during this period and it is therefore more appropriate to repot it earlier in May or June before flowering commences.
Please click on this heading for details of pests and diseases that effect Cyclamen