What is Verbascum
Verbascum is a varied group of biennials, long-lived perennials and short-lived perennials producing insect-friendly spikes of flowers. Two hundred and fifty species are mostly native to Europe and Turkey, all found on poorer, disturbed soil. They are members of the Scrophulariaceae family.
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When do Verbascum flower?
Verbascum flower between May and September and grow to heights that range from 30cm to 2m or more. An upright habit, although some rosettes can be up to 90 cm wide. All verbascums enjoy a sunny, open site with good drainage – excellent for drier gardens. Many have deep tap roots, allowing them to
suck up water in drought conditions.
How to grow Verbascum
Growing verbascums from seed
Verbascum strains and species often set copious amounts of seeds so you may want to remove the seedheads to prevent unwanted seedlings. If you do remove the flowering spikes your plants often live longer. However the winter silhouettes of taller verbascums can be spectacular in the right setting. Commercially available packets of verbascum are easy to find. If saving seeds from the garden, harvest on warm days at midday and cut the seedhead into manageable lengths. Store the seeds somewhere cool and dry.
When to sow Verbascum seeds
- Sow in April to May in warm conditions (roughly 15º-18ºC) in trays of seed compost.
- Press the seeds into the damp compost.
- Move into shade as hot conditions and high temperatures stop germination and halt growth.
- Germination will take between 14 and 30 days.
- Once the seedlings are large enough to prick out (with two proper leaves) transplant them into 7.5cm pots of John Innes No 1 compost.
- Grow on in cool conditions (around 15ºC) until the roots reach the bottom of the pot.
- If in doubt, upend carefully and look at the root ball.
Plant them young before the tap root develops. Either plant out into final positions once large enough, watering regularly until the autumn rains come, or plant at the beginning of September. If the strong tap root on a verbascum gets disturbed it fails, so pot-grown plants from a garden centre should be as young as possible. If you do succumb and buy one in full flower, plant it extremely carefully and nurture it well through its first growing season, particularly if it’s been grown in peaty compost.
How to propagate Verbascum
- All verbascums can be propagated from root cuttings taken between late autumn and March.
- Lift your plant and snip away two or three sections of root close to the crown.
- Remove only one-third of the root system or less and replant the original straight away.
- Wash the roots and remove any fibrous lateral growth.
- Cut each into 5-10cm lengths making a horizontal cut at the upper end and an angled cut at the lower.
- The larger surface area of the angled cut helps the plant develop roots and tells you which end is which.
- Fill pots with equal parts seed compost and gritty sand or perlite.
- Insert each cutting so that the horizontal cut surface is just below the surface, about 6cm apart.
- Top dress with 1cm of grit. Water lightly and place in a cold frame. Pot up once true leaves develop: this can take three months or more. Grow on and plant out once large enough. Pests and diseases Mullein moths can eat foliage in summer and they do pupate close to the rosette in winter. Pick them off if they offend you.
The best types of verbascum for your garden
Mulleins have always been popular for their tall flower spikes, which provide useful vertical accents in the garden. Most are yellow with purple stamens or occasionally white. A few species, notably Verbascum phoeniceum, exhibit a colour range from white to purple. Hybridisation of Verbascum phoeniceum and various perennial yellow species has resulted in some wonderful colour breaks. Verbascum ‘Petra’ has unusual reddish-brown flowers and is one of several cultivars bred by Vic Johnstone and Claire Wilson who formerly held the National Collection of Verbascum. Height 1.2m. Chosen by Marina Christopher
I use many mulleins in the garden and consider this among the best. The towering flower spikes are produced from relatively small, felted, grey rosettes. Once established, it will roam, self-seeding through the border year after year, creating happenchance combinations and providing a dramatic visual link through the planting scheme. Any plants in the wrong place can be dug up as rosettes and relocated in autumn. Flower spikes may be forced over by strong winds. A short stake will keep them vertical. Height 2m. Chosen by Mat Reese
Some verbascum, such as Verbascum olympicum, have a reputation for being tough but not hard to grow. They do, however, need space and their candelabra profile makes them a great border plant. It’s a perennial, but one that you can treat as an annual. 2m.
A rose-madder verbascum with pink to lavender flowers, finely edged in brown. Bred by Vic Johnstone and Claire Wilson, it did well in 2007-2008 RHS trials. H 90cm.
Verbascum ‘June Johnson’
Copper-orange flowers and grey-green foliage make this 1990s verbascum a subtle addition to the garden (although this one can be hard to find). H 90cm.
Verbascum (COTSWOLD GROUP) ‘Royal Highland’
First shown at The Royal Highland Show and similar in colouring to Verbascum ‘Helen Johnson’, although a touch more apricot-pink. H 90cm.
Verbascum blattaria f. albiflorum
Several stems of white flowers smudged in smoky damson-plum, studded with golden stamens. Light, airy and largely biennial. Best in dry gardens or it can flop. H 120cm.
A glowing, warm-toned verbascum that epitomises summer with purple-eyed warm orange-brown flowers. Reputedly longer lived than many. H 60cm.
Verbascum (COTSWOLD GROUP) ‘Pink Domino’
An AGM (Award of Garden Merit) verbascum with tall spikes, easy to place in a sorbet of roses or silvers. Short-lived perennial. There is also a ‘White Domino’. H 100cm.
Verbascum Chaixii ‘Album’
Mauve-eyed small white flowers tightly held on spires. Good with dark roses and traditional summer herbaceous plants. Truly perennial and pretty. AGM. H 120cm.
Verbascum phoeniceum ‘Rosetta’
Long wands of flowers above a rosette of leaves. Seeds freely. May flowering – if deadheaded may re-bloom in autumn. Easy to grow from seed. H 40cm-60cm.
Verbascum ‘cherry helen’
This is a sport from ‘Helen Johnson’ that produced cherry-pink flowers gently washed in warm brown. H 90cm.
Verbascum ‘Valerie Grace’
A pretty verbascum with pink flowers and a darker plum-centre, just showing a touch of orange. Difficult to acquire. H 90cm.