Clematis not blooming – causes and help

Often something is wrong with the location when a clematis causes flowering problems. “The clematis thrives in sunny and partially shaded locations. The water requirement and maintenance effort is low. The new clematis or clematis immediately catches the eye with its blossom, is easy to care for and the ideal climbing plant for your garden” is a typical description accompanying the sale of the freshly acquired clematis. Everything is correct, but a few details are important so that the clematis really “catches the eye with its bloom”:

• A sunny location must not get too warm
• Heat accumulation on the house wall can lead to growth cessation
• Including flower development, flowers that have already developed can be shed prematurely in the event of heat build-up
• “Semi-shady” means shade and sun over the entire season, not shade in March and midday sun in July
• Both locations must offer enough heat, 15 to 22 °C day and night
• The site must provide shelter from rain and strong winds

How to help the clematis:
If the root area is regularly in the blazing sun, the clematis will not bloom. On the other hand, a shady underplanting or pre-planting helps so that the root balls and the lowest part of the trunks are always in the shade. Various (weak-growing) ornamental plants get along well with the clematis: box trees, blue cushions, gold lacquer, lavender, princess carnations such as pink kisses, purple bells, roses, for example. If the clematis is to remain in the field of vision and there is no space for further planting, you can also place a few potted plants in front of it that need fresh air and/or cover the roots with a layer of pebbles, pine soil or bark mulch.

If more location deficiencies were found, you should think about moving the clematis to a better place. To do this, please wait until the clematis has gone into the dormant phase in autumn (even if there are no flowers in the current season, transplanting in the season might be too much stress for an already weakened plant).

cold shock

Unproblematic frost hardy, hardy down to approx. -15°C – these sales descriptions are also correct (mostly), it is only important that the minimum temperature tolerated by the clematis is never undershot. Cold shocks are conceivable in several situations:

• Late ground frost often causes a complete failure of the flower
• It is not uncommon for moderately hardy clematis to be planted in rough locations
• Or the hardiness zone is right, but the microclimate is unfavorable
• If the average temperature is only briefly undershot due to weather changes, the clematis has to fight

How to help the clematis:

• Clematis species that bloom early need protection from late frosts so that the buds don’t freeze to death
• Keep an eye on the weather forecast until the end of May, if necessary protect the clematis at night with fleece or jute around the roots
• Clematis in plastic tubs should be packed well, the material offers very little resistance to frost
• Also protect the tub from below or set it up slightly higher and, if necessary, use the heat radiated from a house wall
• Pay attention to the variety in the cold corners of Germany
• Early flowering clematis often suffer from the fact that the soil and air have not yet warmed up sufficiently at the time of flowering
• Even the large-flowered varieties that flower from the previous year’s wood can lose their buds due to frost and snow
• The clematis that bloom on new wood from early summer until the first frost are clearly the better choice here
• The clematis varieties Blue Bird, Blue Boy, Ruby, White Swan and Purpurea Plena Elegans are extremely hardy

Nutrient supply insufficient

Even without flowers, clematis have to supply a lot of biomass, so overall they belong to the plants that are called “heavy feeders” in the vegetable garden. The clematis does not bloom when it is hungry and thirsty because it no longer has the strength to do so.

How to help the clematis:

• Put plenty of compost and horn shavings in the planting hole when planting
• If this has not been done, loosen and enrich the soil superficially in late winter/spring
• Give nutrient-rich fertilizer at the start of the season and just before flowering
• A shovel of bone meal is also welcomed in spring and again in summer
• Only use high-quality or self-mixed substrate for tubs and enrich with long-term fertilizer
• Fertilize as organically as possible, because these slow-release fertilizers guarantee a sustainable supply
• Only in the bucket is the necessary soil life missing and must be supplemented by shares of readily available mineral fertilizer
• Say goodbye to clematis with potassium-rich final fertilization shortly before autumn when they go into the dormant phase
• Water regularly and sufficiently
• Sometimes in the mornings and evenings when it’s hot
• Also water a little on frost-free days in winter

Wrong cut

Many clematis flowers fall victim to pruning shears because the clematis was pruned at the wrong time.

You can no longer help the clematis in the current season, only choose the right cutting times from now on:

• Spring-blooming clematis lay the flower buds in the pre-season
• They may therefore only be cut after flowering
• But only when they have already shown this flowering once, which can take years
• Clematis that bloom from summer can and should all be pruned from the start
• They are cut in late fall or early spring after the last frost
• That was the safe short version that won’t deprive any clematis of flowering
• There are special cutting instructions for almost every variety, which you are welcome to follow
• You just need to know for sure when this clematis variety will flower and that the pruning time is right

Clematis does not bloom – selection of varieties

Some clematis like to take it easy and first form strong roots, only to then really grow in the upper area and develop the flowers. Well-known late bloomers include the cute little “blue-blooded” ‘Königskind’ and the award-winning ‘Mrs. George Jackmann’ with large white flowers; all the species and varieties that remain small and are also sold for container cultivation are suspect of a slow start.

Other clematis grow magnificently and quickly at first, only to develop their first flowering from the third year and then take a long break exhausted. All clematis that were bred with Clematis alpina, Clematis macropetala or Clematis koreana can show such growth behavior.

You can perhaps help this clematis with even more exemplary care, but it also applies to plants that you can never turn “owls” into “larks”. So when in doubt, just be patient.

Sensitive Varieties

If the site conditions are “just” suitable for clematis, some sensitive varieties simply do not cope well with this environment in the long run.

How to help the clematis: You can help the clematis,
which is currently growing in a precarious location, with many of the measures described in this article, allowing you to choose freely depending on the situation. If you suspect this could be a long struggle, only replanting will help. But this time you should plant an extremely robust clematis that won’t be knocked over easily. Since it might not be easy to choose from the more than 300 clematis varieties, here is a small list of the “clematis varieties for all occasions”:

• Arabella, flowers late and 4 months long, produces more flowers than most other Clematis varieties
• Betty Corning with delicate bell-shaped flowers from spring
• Blue Angel with ruffled petals
• Blue Ravine, violet flowers with dark red stamens from May to September
• Dark Eyes, C. Viticella is a deep purplish purple with black stamens, flowers July to September
• Daniel Deronda, flower size up to 16 cm in diameter
• Fairy Blue, Japanese breed flowering in late spring
• Jackmannii, dark violet classic with many advantages
• Parisienne, new variety with 2 x purple flowers and compact growth suitable for tubs
• Rhapsody, flowers deep blue and large from June to September.

Avoid waterlogging

Some clematis are watered generously and thoroughly every few days, but unfortunately sit in soil that is not sufficiently permeable to water. The name clematis says it all: the original clematis climbs a tree on wonderfully loose forest soils, and the descendants bred in all directions have undergone many changes, except for the aversion to waterlogging – especially the shallow-rooted species Clematis alpina, C. montana and C .orientalis quickly react sensitively to accumulated moisture. Plants need oxygen around the roots, prolonged waterlogging only stops all growth in the case of very stubborn plant nature or water plants; and of course the flower development suffers as a result.

How to help the clematis:
Even loamy soil can be too dense for the clematis and should be loosened up with humus and/or sand. Actually before planting, afterwards you can loosen the soil a bit by poking it several times with the digging fork and/or work in some sand and mature compost with the rake. Mycorrhiza or EM (effective microorganisms) that are simply spread are also said to do amazing things when loosening the soil. The next clematis should be planted slightly higher in such critical soils so that water can run off more easily.

Clematis does not bloom – diseases

If the clematis does not bloom and also appears limp and wilted, the dreaded clematis wilt could be at play, which has at times affected up to 80% of the newly planted hybrids in Bavaria.

How to help the clematis:

• Prune infested clematis back to healthy wood immediately
• Dispose of prunings in the residual waste and not on the compost
• Most of the time, the clematis will sprout again, but this can take up to a year
• If you live in a wilt area, you should switch to resistant varieties in the long term
• The Bavarian State Institute for Horticulture has tested varieties over the past 20 years
• The pure species in particular show good resistance to clematis wilt
• So the summer-flowering C. viticella in a large number of varieties
• C. integrifolia, texensis, tangutica, alpina, macropetala and montana too, but in decreasing numbers of varieties
• With the hybrid varieties, wilting cannot be completely ruled out, but some old classics such as Jackmannii also do quite well

Compare time and benefit

Are there “Monday plants”? If, after a little improvement in care, one clematis on the terrace blooms great and eagerly, the other right next to it (in the same soil and under the same sun) responds to any attempt to influence it with a defiant “I don’t want to bloom!”, you could do it come up with such an idea. Anyone who believes that every deviation from normal behavior has its causes will not necessarily accept it that easily. And indeed, closer investigation could reveal that the flowering-refusing clematis is getting a little less sun or has received a little less fertilizer or has already suffered damage in the store or has become a little more sensitive through breeding or does not flower because all these influences and more come together.

The practical question is therefore how long it is worth investing time in investigating the causes once the major errors have been rectified/excluded and a cause could emerge in the end, but unfortunately not much can be done about the effects. If a plant does not want to, despite all your efforts, patience will help at first and then at some point the only thing that will help is planting a plant that is in a better mood.

Conclusion
Even if a plant is sold as easy to care for and its German name Waldrebe also sounds very much like it, every clematis variety has its special needs, the non-observance of which “can affect the flower”. Various causes can be explored and remedied. Optimizing care down to the smallest detail can arouse the desire for flowering in many clematis; but sometimes it gets so complicated that you should probably just say goodbye to this plant (after a last chance with pruning and waiting for new growth).