Dianella is a grassy sort of plant, with long, green leaves that are strap-like and stand upright, or become more arching as they get older. The leaves are evergreen, produced from the centre of a tuft of foliage. Also from the centre, flower stems are produced in early summer. The flowers are generally blue, but there is a lot of variation in the shade of blue, from pale lilac to deep blue, and there are some white-flowered forms. The flowers are star-shaped, usually reflexed and pendent, with prominent yellow stamens protruding from the front of the flowers. They look a bit like the flowers of the potato family, but they are not related, instead being members of the phormium branch of the greater lily family.

Noting that dianella is part of the phormium family, the New Zealand flax, makes sense straight away, because the resemblance is immediately obvious. Dianella looks like a miniature version of the phormium, with which most people are familiar. It has the strappy leaves, though much narrower, and spiky, pointed ends, and it is evergreen. The only part that does not resemble phormium are the blue flowers.

The dianella flowers differ in that they are shorter, much more branched and more airy and open in appearance. However, quite often the flower stems do not emerge much higher than the leaves, at most about halfway out. Presumably this helps to protect the flowers and the berries that are produced.

The blue berries are not obvious from a distance, being half-hidden by the foliage, and often the stem carrying them is bent over with their weight. But they are a pleasant surprise and, when seen close are very eye-catching, carried prettily on slender stems in a rounded head of berries. The berries are the size of a smallish grape, sometimes rounded or more oblong. The colour is omehwat metallic and the berries last well into autumn, becoming more worn-looking as time passes. But they bring a most unusual colour to the mix of autumn shades, even though they are not prominent.

There are two kinds of dianella grown in gardens, both from eastern Australia, including Tasmania. The most common kind is Dianella caerulaea, which means blue dianella, but the other kind, Dianella tasmanica, also has blue flowers. The second kind is taller, to about one metre, which is twice as tall as the blue dianella, but there is a lot of variation with the species and much depends on the quality of the soil. Very rich soil sees a response of vigorous growth, which is fine where there is space available but, like phormium, it can get too big for a small garden. The tufts of robust leaves spread out to make a dense mat of foliage that is completely weed-resistant.

Dianella is best grown in soil of moderate fertility – do not use any manure or fertiliser when planting. It produces more flowers and berries if the soil’s not too rich. It should not be prone to drying out too much in summer, as this causes patches on the leaves and their tips dry out. Dianella is a woodland plant in its native region and it is very tolerant of shade, and can grow right under trees and large shrubs. So it can be useful to fill an awkward spot. The foliage stays in better condition in shade, but flowering and berrying is reduced. A position of some sunshine strikes a good balance of leaf growth and flowering. It is not fully hardy, but seems to be at least as good as phormium. CL

Jimson weed

Jimson weed is native to North America, and it is also known as thorn apple. It has begun to appear in Irish gardens, generally in the vicinity of bird tables. Jimson weed and other weeds are sometimes present as contaminants in bird-food and spring up from time to time. The plant is low-growing, usually, and spreading with oval leaves that have irregular, jagged edges.

Tubular white or yellowish flowers are formed, followed by a spiny, rounded seed pod. It is a species of datura and like other datura, such as angel’s trumpet, it is potentially very poisonous, causing hallucinations, convulsions and even death. All parts of the plant are poisonous and while it is unlikely to be ingested, it is possible. It is likely to die out because it is killed by frost and is unlikely to set viable seeds, but it might.

Fruit, vegetables and herbs

Mixed weather has suited vegetables quite well, but weeds have grown well too and should be controlled before they shed seed. Remove the tops of potatoes if potato blight has come. Remove apples or pears attacked by wasps, including windfalls, to avoid more damage.

Flowers

Keep up watering and feeding of baskets and other containers for a full month or so, to get the best of them in autumn. Remove seed heads of flowers such as alchemilla and dierama that are inclined to self-sow in the wrong places and that can be difficult to root out.

Lawns

The rain has been enough to keep grass growing, although there were signs of drought on lighter ground a few weeks ago. Maintain regular mowing to create a tight sward that will compete with lawn moss. If grass has grown poorly, use a low-nitrogen lawn fertiliser.

Trees, shrubs and roses

Water all young shrubs or trees that are showing signs of drought, including thin leaf cover, small leaves and leaves colouring prematurely. Water and feed camellias in pots to encourage the formation of flower buds for next year. Prepare ground for autumn planting.

Greenhouse and house plants

Stop all feeding of greenhouse and house plants and ease off the watering, except for winter flowering plants, such as winter cherry and azalea. Remove plant debris to reduce grey mould disease. Remove any flowers and small fruit that develop on tomato plants.