For a long time, the plate hydrangea was regarded as a ‘poor relative’ of the farmer’s hydrangea and was neglected by breeders and traders. It attracts gardening enthusiasts with individual charms, such as a filigree habit that reveals itself in a graceful growth form and two-tone, flattened flowers. Those who cannot get used to the floral force of garden and farmer’s hydrangeas will get a horticultural design element with the plate hydrangea (Hydrangea serrata), with which even shady places can be transformed into blooming landscapes.
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The plate hydrangea comes from the twilight, rainy mountain forests of Korea and Japan. Your requirements with regard to the location and the nature of the soil are accordingly:
- A location in the light shade is ideal.
- A sunny location is tolerated with sufficient moisture.
- Humus, nutrient-rich potting soil with airy pores.
- The pH tolerance ranges from 5 to 8.
- A slight lime content in the substrate is not a problem.
The plate hydrangea harmonises perfectly with deep-rooted deciduous trees in the immediate vicinity, because it knows how to use the advantages of this location. Under the dense canopy of leaves, the hydrangea is protected from hot sunshine and pounding rain. Nevertheless, it is spoiled in the morning or in the evening with the milder rays of the sun. Since the Hydrangea serrata, with a stature height of around 100 cm and the discreet, plate-shaped flowers, is by far not as dominant as its conspecifics, it fits wonderfully into sunny herbaceous borders, as long as it is supplied with sufficient water.
The botanical name Hydrangea already indicates what is important when caring for the plate hydrangea, because translated it means ‘water vessel’ or ‘a lot of water’:
- The ideal planting time is in May.
- Water abundantly at each location.
- The plate hydrangea is particularly thirsty in the bucket.
- Nevertheless, it is essential to avoid the formation of waterlogging.
- Prefer collected rainwater.
- Repot plate hydrangeas in the bucket in good time.
The high water requirement of the plate hydrangea, even in shady places, is explained by the large leaf area, over which a lot of water evaporates even outside of the flowering period. It is therefore important not only to provide the subshrub with the required moisture during the flowering phase from June to September, but also at any time of the year as long as it bears its leaves and it does not freeze.
As much as the withered flowers in late autumn may tempt the hobby gardener to use secateurs, pruning at this point would have fatal consequences for the plate hydrangea. Since the majority of the varieties attach the flower buds to the wood of the previous year, the splendor of colors that is longed for in the coming year will be gone when the cut is made in autumn or winter. In addition, the experienced gardener knows that his hydrangea sheds its leaves, but the dried inflorescences remain on the bush. If they are covered with hoarfrost, snow and frost in winter, they undoubtedly adorn the otherwise dreary garden. In early spring, the time has come to support the approaching abundance of flowers with a light pruning:
- Cut frozen shoot tips.
- Cut out all dead wood near the ground.
- Cut off inward-facing branches.
- Eliminate crossing shoots.
- Remove the dead flowers.
- Make the cut just above the new buds.
- Do not leave long branch stumps (coat hooks).
- Use only sharp, disinfected cutting tools.
- Never squeeze branches and shoots.
Incidentally, it is very easy to determine whether an instinct is still alive. A little bark is scraped off with the fingernail. If green tissue appears, this is an unmistakable indication that the secateurs should not be used here. If this type of maintenance pruning is carried out every year, there is no risk of the plate hydrangea becoming bald from below because light and sun can reach all parts of the shrub. If the gardener fails to regularly clear out, the Hydrangea serrata will hopelessly wither. Then only a radical rejuvenation cut to 15 cm to 20 cm in the hope that the plant will recover and sprout again after two to three years will help.
Plate hydrangeas can cope with temperatures around 0 ° Celsius and light frost in the bed; However, if winter shows its cold side, protection is advisable. The root area is covered with a thick layer of leaves, straw, or sticks. The twigs and shoots are given a protective cover made of garden fleece, bubble wrap or jute sacks. On frost-free days, the knowledgeable hobby gardener treats his plate hydrangeas to a dose of soft water so that the already established flower buds do not dry out. As soon as the temperatures fluctuate permanently at a level above 0 ° Celsius, the winter protection is removed so that no mold forms. The cover may be pulled out again if the weather forecast mentions late frosts in the time between budding and flowering.
In winter, the plate hydrangeas are exposed to the risk of the root ball freezing through completely in the tub. You should therefore move to a light, cool but frost-free winter quarters, where they are also not allowed to dry out.
Bring the hydrangea to bloom
If the hydrangea does not want to bloom at all, this can be attributed to various causes:
If the instructions given for cutting the plate hydrangea are not taken into account, the hobby gardener deprives himself of the flowers in the next spring.
Since the hard-working plate hydrangeas start sprouting as early as the end of March, severe late frosts can damage the buds to such an extent that they do not flower. The winter protection that has already been put aside should therefore still be ready to hand by mid-May.
If the Hydrangea serrata is a bit lazy, it may be because it is not getting enough nutrients. In this case, it is advisable to do a soil test first. In garden centers and online shops, practical test sets are offered for less than 5 euros, which can be used without prior chemical knowledge. The degree of acidity of the potting soil is displayed on the basis of discoloration, from which gardening enthusiasts can conclude what the plate hydrangea is missing so that he can make it bloom. For example, if the pH turns out to be too high, the plant cannot absorb enough iron, which ultimately prevents flowering and causes the leaves to turn yellow. An adequate pH value alone may not be enough if the plate hydrangea is to be made to bloom. Only in connection with a special hydrangea fertilizer are the chances of a splendidly blooming shrub. The special thing about this fertilizer is the lower proportion of phosphorus compared to conventional complete fertilizers. For this reason, the use of blue grain with a high phosphorus rate is completely unsuitable to stimulate the flowering of the plate hydrangea. In contrast, the use of good garden compost is much more environmentally conscious and cheaper. Regularly incorporated into the soil, this natural fertilizer ensures a balanced soil quality in the long term, for which the plants thank you with beautiful flowers. Only when a plate hydrangea that is actually blooming blue is increasingly turning light with a tendency to pink does the knowledgeable gardening friend go to the pharmacy and buy alum (aluminum sulphate) there, also called hydrangea blue. With the help of this agent, the required low pH value of the soil and thus the deep blue flower color are preserved. Alternatively, acidic compost is prepared and incorporated into the substrate.
Make acidic compost yourself
For gardens that are home to a large population of hydrangea or a high proportion of flowering plants that prefer an acidic soil quality, it is advisable to create an acidic compost heap. In addition to the conventional components of a compost heap, such as plant residues, lawn clippings, vegetable and fruit waste, 10% of the following substances should be included:
- Pine needles
Hobby gardeners, who have to deal with a large volume of leaves every year, create a pure leaf compost heap:
- Mix the different types of foliage.
- Pour into a composter or a suitable container.
- It must not have a closed or solid floor.
- As a first layer, fill in coarse material such as branches and twigs.
- If possible, chop up the leaves so they don’t stick together.
- Pour alternately with thin layers of garden soil.
- Use compost accelerator if necessary.
If the leaf compost heap is moved in spring, the acidic fertilizer is available from autumn. It is important to note that it is only lightly worked into the potting soil of the plate hydrangea and never buried. Thanks to this measure, the plate hydrangeas receive all the nutrients they need to develop abundant flowers, while at the same time ensuring that blue hydrangeas stay blue.
Once the plate hydrangea has established itself as a decorative, long-blooming design element in the garden thanks to careful care and regular cutting, the desire for more specimens quickly arises. The method of propagation with the highest success rate works with the help of cuttings. In the period from the end of May to June, several shoots are cut off from the mother plant, each just above a bud. They should have two pairs of leaves and a length of 10 to 15 cm. The two leaves at the lower end are cut off because the cuttings should develop a new root system at this point.
Garden enthusiasts who know their way around, force the process by dipping this part of the shoots in rooting powder made from seaweed extract or in willow water. The cuttings spend the next 14 days in a small pot filled with potting soil, which is kept slightly moist and covered with cling film. After a further 14 days, the rooting has progressed so far that the film can be removed. As soon as the seed pot is completely rooted, the young plants are repotted. In the cold season they join the potted plants in the light and cool winter quarters until the plate hydrangeas can be planted in the bed next spring.
A wide range of brightly colored varieties of plate hydrangea means that committed hobby gardeners are spoiled for choice:
Hydrangea ‘blue tit’
- Growth height up to a maximum of 130 cm
- wonderful blue flowers
- Flowering period June to September
- Alum gets the blue color
Teller hydrangea ‘Pheasant’
- Height of growth 100 cm to 130 cm
- decorative purple flowers
- Flowering period July to September
- bushy and upright growing
Tellerhortensie ‚Lanarth White‘
- Height of growth 90 cm to 120 cm
- brilliant white flowers
- Flowering period July to September
- ideal for the small garden
- Growth height up to 140 cm
- inner flowers are purple
- the outer pseudo-flowers light blue
- Flowering period July to October
- particularly robust variety
Filled hydrangea You & Me ‘Romance’
- Height of growth 100 cm
- Flower color pink or blue depending on the pH value
- Flowering period June to September
- hardy to -25 ° Celsius
Instead of dominance, the plate hydrangea scores with grace and graceful habit. It has long since emerged from the shade of the farmer and garden hydrangeas, which are related to it, and precisely because it also thrives in the light shade. Those who familiarize themselves with their requirements in terms of care and pruning will enrich the garden with a perennially flowering subshrub with a charismatic charisma. A special fascination in the cultivation of the Hydrangea serrata lies in the fact that it is up to the gardener what color the flowers appear. This brings an unimagined amount of exciting entertainment to hobby gardening.