Gardening - Blue Bird hibiscus

After a slow, cold and wet spring, the mixed summer weather of sunshine and showers has resulted in remarkable growth in gardens. Some plants are great indicators of a good growing year and one of the best is ‘Blue Bird’ hibiscus. In a good year, it flowers in the middle of August, and in a poor year not until early September.

Flowering times vary in different parts of the country but this year it flowered in mid-August and it will flower well into September – the length of the flowering being curtailed by wet and cold weather.

But, at least, ‘Blue Bird’ flowers – there are other related varieties of hibiscus that do not manage to produce even a single flower in a dull, cool summer.

‘Blue Bird’ is the hardiest and most resilient variety, which is why it is more often seen in gardens than the others. Its colour is a slightly muddy purplish blue with a red flash at the centre of the flower. It carries a good showing of flowers on a large bush.

‘Blue Bird’, also sometimes called ‘Oiseau Bleu’, is a selection of the species Hibiscus syriacus, the Syrian hibiscus. The winter weather in that region can be very cold, and this hibiscus is hardy. It is deciduous, which is usually an adaptation to survive cold winters.

The leaves are a pointed diamond-shape with three or more indentations. But the new leaves do not appear until late May or June, sometimes well into June, so it is not too surprising that this Syrian species of hibiscus often runs out of good summer weather before flowering can get much underway.

In its home range, it would get a scorching hot summer with plenty of sunshine and would respond with quick growth and earlier flowering. The flowers are about 8cm across, flat and shaped like hollyhocks, mallow or lavatera, as these as all part of the mallow family.

There are other varieties of hardy hibiscus, none as reliable as ‘Blue Bird’ but more prettily coloured in shades of red or white and red. ‘Woodbridge’ has deep pink flowers with a red throat. ‘Red Heart’ has white flowers with a red flash at the base of the petals. ‘Diana’ has large, pure-white flowers. ‘Hamabo’ has pink-flushed white flowers with a dark-red centre. ‘Mauve Queen’ has pink-mauve flowers.

All of these have single flowers, which cope with cool weather –better than double-flowered kinds that might make a lot of flower buds and fail to open any of them. The double kinds are often grafted on a seedling rootstock that has purple-blue single flowers and, if a sucker gets away, it often produces flowers while the grafted variety does not. There are also the tender hibiscus kinds, but those cannot be grown outdoors.

Syrian hibiscus likes well-drained soil, though not very dry, and it grows best in good fertile soil that boosts growth in its short summer. It is not a great competitor against other shrubs – either above ground or at root level – so try to find a place where trees and big shrubs, or hedges, do not compete strongly and slow its growth to a standstill.

Being a special shrub, it should get some general fertiliser or tree and shrub fertiliser in spring and it would be a good idea to water it during a dry spell, giving it a liquid feed, but not when the ground is dry. Hardy hibiscus is a bit marginal but lends an exotic touch of warm country atmosphere in its best flowering years.

Trees, shrubs and roses

Climbing and rambling roses that finished flowering can be pruned and tied in while they are still manageable. Preparations for autumn and winter planting can be made now, controlling existing grass and weeds, especially all perennial weeds, such as bindweed, before planting.

Flowers

Bedding and container annuals will last longer if given some liquid feeding now — they still have at least a couple of months of flowering but will stop long before without feeding and regular watering. Spring bulbs have appeared in the shops and it is a good time to plant.

Fruit, vegetables and herbs

The vegetable garden has gone past its summer peak, with early cabbage and cauliflower, carrots, French beans, broccoli and peas finished and second sowings ready. Sweetcorn is coming in nicely having grown very well this summer. Control weeds before they shed seeds.

Lawn

Grass was growing strongly all summer with showers but slowed down in places when the dry spell came. Recent rain has helped but has not penetrated the surface layer of soil. Keep mower blades up a notch for now and keep lawn edges trimmed for a neat look.

Greenhouse and house plants

Stop feeding most greenhouse plants now, because they will have enough in the pot to keep them going, and reduce watering gradually to toughen permanent greenhouse plants before winter. Pick greenhouse tomatoes, peppers and cucumbers as they become ready.

Lifting onions

Although onion sets went into the ground only in the third week of April, they quickly made good growth and the sunshine and showers kept them growing strongly. The dried weather in August saw them cease growing and the tops fall over. Allow the toppled leaves to wither back a bit before pulling the onions. They should come away from the soil quite easily and if they do not, then leave them for a week or so for the roots to weaken. Lay the pulled onions out in full sunshine or in a glasshouse if available to ripen. The harder and better ripened the onions are, the better they will last in winter store.