We have a particular plea for articles this month from Rosemary Horsey. She writes… “I garden on chalk on a south-facing slope so the shady parts are extremely dry. I should be very interested if the newsletter could address this problem from time to time and I am sure there are others with the same problem.”

I have only ‘book learning’ on this subject, living as we do in a usually soggy part of North Wales. Those of you with direct experience please tell us about it. What has worked and what has failed? It does not have to be a long article … a few knowledgable lines can help.

Please send items on this, or any other subject to wasjsime@gmail.com

Plant of the Month: Actaea rubra

I know it is common, but that doesn’t stop it being the star of the shade garden at this time of year. I grow quite a few plants in which an attractive feature is berrying in autumn (triosteum, arisaema, arum, aralia, polygonatum etc.). Of these Actaea rubra is the first to deliver each year and is at its best in early August before the birds start to strip the spikes of their shiny red berries.

Actaea rubra

Actaea asiatica

The foliage is attractive, being deeply lobed and toothed, forming a light green mound. The flower spikes appear in the spring and are white. They are reported to grow as tall as 30 ins, but mine are usually between 18 ins and 2 ft. The berries start green and turn red in late July/early August. There is a white berried form (Actaea rubra f. neglecta). To make matters even more confusing, there is a second North American species A. pachypoda which has white berries with a conspicuous black dot making them look like dolls eyes, and this species also has a red berried form. In our garden A. pachypoda ripens a little later than A. rubra. As with many of the ranunculaceae, all parts of the plant are poisonous, particularly the berries. They are, however said to be extremely bitter and there are no reported deaths from this plant. Low doses are said to be psycho-active, and there is a good account of someone taking a dose in the Wikipedia article on the species.

They are relatively easy to grow and are happy in any shady site. They are simple to grow from seed. You ‘squish’ the berries in water, swirl-off the pulp and sow the seeds. But if you have allergies, or are worried about the poisonous nature of the plant wear latex gloves for the ‘squishing’. Plants take a few years to establish themselves and berry reliably, but are worth the wait.

There are two species of berrying actaea native to Eurasia, A. spicata and A. asiatica. I grow the latter. It is very similar to A. rubra, and the black fruits ripen at about the same time. Both seem to be attractive to birds, and you often find seedlings popping up in various parts of the garden.

Arisaema from Seed

The photos show the developing fruit spikes on two of my arisaema. The berries on many species will be ripening soon, and there are usually several offered in the seed distributions, so it seemed useful to say a little about growing them from seed. Buying flowering-sized tubers can be quite expensive, and so if you want a decent population at a reasonable cost, seed is probably the best option.

Many species are shy to set seed. Their sex lives can be a bit complicated. Firstly the spadix can have either male or female flowers, or both, depending often on the size of the tuber. Secondly, the usual pollinator in their homeland will not be present in our gardens, and it is pot luck as to whether one of our native flies or beetles will do the job. Even if the spadix has both male and female flowers, these may not ripen at the same time. (A. flavum subsp. abbreviatum is an exception and is reliably self-pollinated.) In his excellent book, Gusman describes a procedure used by growers in the USA to ensure pollination, involving a fridge, a blender and some washing up liquid, but few of us will be willing to go to this extreme!

The berries are ripe when they are red or orange. The time of ripening will vary according to both the species and the climate. If the berries are still green when the plant is cut down by the first frost, do not give up. Bring the fruiting spike into a cool room and they will ripen slowly. We have done this successfully with A. speciosium var magnificum. I brought it into the conservatory in mid-November, the fruit turned red in mid-January and we now have several seedlings growing on well.

Arisaema cilliatum developing fruit

The fruits contain germination inhibitors and so the seed must be well cleaned before it can be sown. Even if your hands are only slightly sensitive it is worth wearing latex gloves as the fruits contain microscopic calcium oxalate crystals which can be irritant. Squeeze the berries and pop-out the seeds into a shallow bowl of water. Then rub the seed gently to remove any residual material. They are probably best sown immediately, but we have had reasonable germination from quite dry seed collected in the Himalaya by Chadwell.

We sow into our ‘standard woodland’ compost which consists of 3 parts multipurpose compost and/or leaf mould, 2 parts John Innes No1 and 1 part horticultural grit or perlite. The compost should be kept damp but not wet. Visible germination can be quick or take up to 2 years, however many species germinate below the soil and only put up their seed leaves some months later, hence the need not to let the compost dry out. The seed leaves either have a single, spear-shaped leaf or a trifoliate leaf, depending on species. In the spring of the year following the appearance of the leaf it is worth tipping out the pots, locating the tiny tubers and potting them up individually. It is now a matter of patience. Whilst A. flavum may flower in its first full year, most will take between 3 and 5 years to develop flowering sized tubers. Luckily we are growing them as much for the foliage as for the flower.

Arisaema hastate seedlings

Arisaema trifoliate seedlings

It is probably advisable to keep them in the pots until the plants look big enough to take care of themselves. Remember that the tubers will be destroyed if they get frozen. Whilst they are in their pots make sure that they are well insulated in the winter, or better still put the pots into a frost free greenhouse. When you plant them out put them deeper than you think you should. Guzman points out that there is a trade off between planting deep (as much as 8 ins) and making sure that they are not below the water table in winter. They will rot if not well drained. Raised beds and borders help.

The less hardy species will benefit from a protective mulch in the winter.

I hope you feel encouraged to have a go.

Available Seed

If you are a paid up member of the Shade and Woodland Plant Group and would like any of the seeds listed below, please send a SAE to S.J.Sime, Park Cottage, Penley, Wrexham LL13 0LS.

If you have seed to donate, please send it to the same address.

Beesia calthifolia

Mitella breweri

Mitella makinoi

Cardamine kitabelli

Erythronium hendersonii

Pachyphragma macrophyllum

Actaea rubra

Actaea asiatica

Hydrophyllum virginicum

Shade Charades

Guess the species. Two words.

First word: three syllables… sounds like an insect's auditory organ

Second word: four syllables…

• First syllable: a small wooded valley
• Second syllable: at the end of a foot
• Last two syllables: make her replete.

The solution to last month's charade was Hosta fortunei. Although still recognised as a species by ‘The Plant Finder’, the Kew/Missouri Plant List has it as a synonym of H. sieboldiana. However, it is best known as a group of related medium-sized hosta cultivars, many with variegated leaves and attractive violet flowers. They tend to be vigorous and easy to grow, even if their taxonomy is in some doubt!

Joe Sime

The HPS Shade and Woodland Plant Group is open to all members of the Hardy Plant Society. Please follow this link for more information.