Last November, I wrote a blog about some of my favourite perennials with spires of bloom, such as the Linaria purpurea pictured left. This month seems to see these plants at their very best, and this year I have enjoyed some different varieties: some in other people's gardens and some in my own. The ones that have caught my eye have all, coincidentally, been plants that are prone to self-seeding (which incidentally the Linaria does too!): scattering themselves through the garden from year to year. They are generally biennials or perennials that are short lived - perhaps because of our climate with its hot, humid summers and mild winters. Not everyone likes plants that self-seed but I enjoy the rather wild, unplanned effect that they create, and excess seedlings are easily pulled out or dug up for friends. I love the vertical element that these plants supply when in bloom - it brings back memories of my cottage garden days!
The first plant - the foxglove - (Digitalis purpurea) is a very old favourite and not one that I have in my garden at the moment, but seeing some beautiful tall specimens in other gardens this spring has made me want to grow them again. The best for Sydney is this biennial sort, which needs to be planted out as seedlings by early April at the latest, to give them time to grow sturdy enough to bloom. They can get very tall - up to a metre or more in height - and may need some discreet staking to stop them from being damaged by wind and rain. The beautiful flowers of purple, pink or cream are intensely spotted and the spires really do give that quintessential cottagey effect. They look lovely with roses, poppies and other perennials, and I saw a stunning group of white ones growing in a woodland setting this spring, amongst shade-loving plants such as hellebores and arum lilies. They will grow in sun or part shade. They will self-seed as long as the ground is not heavily mulched - this seems to apply to most self-seeders. For plants like these that I do want in my garden, I leave some gaps in the mulch cover here and there. Digitalis belong to the Scrophulariaceae family of plants.
Another biennial plant that I have had in my garden for many years that belongs to the same family as the foxgloves is Verbascum blattaria, sometimes known as moth mullein. For some time, when I was very much into a totally tropical look, I used to pull out the shiny green seedlings with their scalloped-edged leaves, as I thought them inappropriate for my garden, but these days I have a more hybrid look, as I found I couldn't live without some of the plants that are not strictly tropical ones. So I have let the Verbascum flower, and have rediscovered how attractive it is. It has tall spires of white flowers with a purple eye, and the stems seem quite sturdy and rarely in need of staking. They don't take up a lot of room at ground level so can squeeze themselves in amongst other plants quite well, but they are best near the front of borders so that they don't get grown over by taller plants. I don't find it self-seeds too much. It grows best in a hot, dry position. I have never had much luck with any other species of Verbascum in my garden.
Teucrium hyrcanicum (ht 70 cm) is an interesting perennial plant from Iran and countries nearby: it has a low basal clump of deep green textured foliage and long spires of purple spires during mid to late spring. It thrives in very dry conditions and enjoys sun: though I have one blooming quite well in a partly shaded spot. I enjoy seeing it partnered with plants that have leaves with a purplish tinge or underside, such as some of the Cape Angels Plectranthus cultivars and Tradescantia pallida 'Purpurea'. I cut it right back after flowering. It does self-seed quite determinedly but so far, I wouldn't call it a nuisance.
I have never had much luck with the Salvia that have a basal rosette of leaves as they seem to rot off during summer, but one such species has done very well in my garden over the years: Salvia forskaohlei (ht 80 cm). It has enormous velvety leaves and sends up branched spires of flowers over a long period from spring till late summer. The most commonly seen form is a mid-blue hue but there is also a nice white form that I have seen occasionally (pictured at left). The advantage of this Salvia is that it blooms well in shade and looks effective in a woodland setting or grown amongst Hydrangea or Justicia carnea both flowering at the same time. It self-seeds gently and is never unwelcome wherever it springs up.
Other spired plants I have admired in gardens over the past few months have been annual larkspurs and lupins, the towering Echium fastuosum and various Kniphofia cultivars, as well as some stunning Penstemon, which (sob) I find I cannot seem to grow well in my Sydney garden.
Tall summer volunteers
24 Jan 21
These will provide colour and form in your garden every summer.
A neon rainbow revisited
17 Jan 21
Hot-coloured flowers still feature in my summer garden
The zucchini files
10 Jan 21
Zucchini can be a rewarding summer crop.
Random musings on a walk
03 Jan 21
Lots of plants caught my eye on a walk.
13 Dec 20
Cut flowers for Christmas vases