Article by David Marks
Heleniums (sometimes called sneezeweed) are very much low maintenance, flowering perennial plants (slugs aside at their early stages) which can grow from as low as 60cm / 2ft to 2m / 7ft high depending on variety. They can be pruned in June to keep the height lower but this will delay flowering for a week or two.
Use the checklist below to decide if Heleniums are suited to your preferences and garden conditions:.
- Height is anything from 60cm / 2ft to 2m tall. The taller varieties will need staking or at least some support.
- They need a full sun or partial shade position and many varieties need to be protected from strong winds when fully grown.
- Heleniums do best in a moderately firm soil. Clay with some organic matter added is the ideal, sandy soils are the worst.
- The soil needs to be able to retain moisture, dry soils will cause the plants to wilt.
- The start to flower from mid July to early August depending on the variety. If the flowers are dead-headed Heleniums will continue to produce flowers for two months. They are a huge magnet for bumble bees and many other insects.
- Heleniums make excellent cut flowers. Dead head them to prolong the flowering season.
- They are not suited to containers. If you do try and grow them in containers they will need frequent and thorough watering throughout the whole summer.
- They are fully hardy in all parts of the UK (and even the very coldest parts of Europe) easily tolerating frost down to below -20F.
- After three or four years flowering will start to deteriorate. The solution is to divide the plants and then replant. One three year old Helenium can be divided into four new plants without any problem.
- Heleniums can cause skin, nose and eye irritation for humans (hence the name “sneezeweed”). I can find no reference to them being dangerous otherwise to humans but that is not conclusive. If sheep or cattle eat them (they normally avoid them) it can cause serious complications.
WHERE AND WHEN TO BUY HELENIUMS
The best time to buy Heleniums is in April time, they can then be planted after being hardened off for a week or two first. Heleniums are widely available at garden centres in the UK but the widest range is to be found online.
Crocus sell an excellent range of these plants online and in our experience the prices and quality are top class. A huge range of Heleniums can be found here all with the Crocus reliable five year guarantee. Also see our independent page dedicated the best varieties of Heleniums readily available in the UK.
HOW, WHEN AND WHERE TO PLANT HELENIUMS
Planting from pots is the most reliable method as described below:
- Choose a sunny position, if only partial shade is available, plant the yellow varieties – the redder the flower the less likely it is to colour up well in partial shade.
- Choose a soil which will retain moisture, Heleniums will tolerate slight water-logging better than most plants. Clay is fine. Avoid sandy soils.
- The best time to plant Heleniums is around the last week of March.
The plants need to establish themselves well before winter so don’t plant them after the end of June.
- Harden the plants off for a week or two before planting them.
- Dig a hole twice the width of the root ball. Sprinkle in a handful of blood, fish and bone and work into the ground.
- Place the plant into the hole, filling in with soil so that it is at the same depth
- Fill around the root ball and firm the soil down gently but firmly. Water well to settle the surrounding ground around the root ball. Add 5cm or so of mulch around the plant to conserve moisture.
- Protect the Helenium plants from slugs and snails when they are young and tender. This is essential. When the plants grow in a month or so the snails and slugs leave them alone.
DIFFERENT VARIETIES OF HELENIUM
There are many, many varieties of Helenium and some definitely grow stronger, taller and produce more flowers than others, so click here to see our list and pictures of recommended Helenium varieties.
As far as general health is concerned there is very little difference between Helenium varieties. All varieties (except “Double Trouble”) are very attractive to butterflies, bees and lots of other insects.
Read descriptions on the internet or plant labels in the garden centre and make your choice based on where in your garden you want your Helenium to grow and what specific features you require.
CARE OF HELENIUMS
The key care tasks for Heleniums are listed below. More information about each care item can be found below the list.
- Dead head the flowers throughout the year, this definitely encourages a longer flowering time.
- Mulch in spring with well rotted organic matter, this will encourage water retention and keep the roots cool.
- Feed with blood, fish and bone fertiliser in spring.
- Clear away the previous year’s stems in spring. Helenium seed heads on the dead stems are a favourite food for finches of all types so don’t remove them before spring
- Water well in dry conditions, Heleniums do not like dry conditions at all.
- Support taller varieties (over 1.2m / 4ft high). For those who are feeling particularly well off, Crocus sell very attractive Helenium plant stakes. They can be used to support other tall plants as well. They make a very beautiful but practical present for the gardener. Click here for details of a suitable flower stake.
- Divide every three and replant (see below).
DEAD HEAD FLOWERS
All Heleniums produce flowers, typically beginning in mid to late summer. To help prolong the flowering period, snip off the flower stems just below foliage level when the flowers die.
Heleniums should not need to be fed quick release nitrogen fertilisers. The combination of mulching and a handful of fish, blood and bone in spring and autumn will provide them with all the nutrients they need.
Early spring is the best time to refresh your helenium. Remove any stem from the previous year and clear away any dead leaves.
At the same time check that temperature changes haven’t caused the plant to lift out of the soil. If this has occurred, fill in any gaps with crumbly soil.
Applying a mulch in spring will help conserve moisture throughout the dry summer months. It will also provide a low level of nutrients as the mulch decays. The best mulch is well rotted organic matter, your compost heap is a good source of this.
During freezing and windy weather in winter, Heleniums can sometimes lift out of the soil leaving gaps around the roots. A spring mulch will not only help to prevent this but it will fill in any gaps around the crown. Do not mulch the centre of the plant, this could cause the crown to rot.
HOW TO DIVIDE HELENIUMS
After about three years, certainly after four years, your Helenium will begin to look bedraggled and the foliage will no longer be in good condition. That is the time to divide it and grow as many new plants as you require. Late April to early June is a good time to do this because the new plantlets will root quickly and will be well established by the time winter arrives.
Use a fork to dig up the rootball. If you then wash the roots in water or use a hose to get most of the soil off, it’s easy to separate the rootball. We divide them into four but it’s quite possible to separate out each rosette.
Replant the divisions to the same depth as before in any sunny position as you would if you had bought a potted plant (see here). If you have too many, pot some up into pots full of multipurpose and firm in well. Water well, Heleniums do not like their roots in dry ground.
PESTS AND DISEASES OF HELENIUMS
Heleniums are normally healthy plants. The following problems below may occasionally occur.
SLUGS AND SNAILS
Young Heleniums are very tasty to slugs and snails but established plants are rarely affected. Either keep a watch out and manually remove the pests or put down slug pellets.
Some cheaply produced potted plants suffer from eelworm and Heleniums are no exception. If a potted plant affected by eelworm is planted in the garden, the eelworms may well persist. So the absolute first line of defence is only to buy from a reputable supplier and only buy plants which look healthy.
Eelworm are tiny worm like creatures which can be found in the roots and stems of Heleniums, they are only just visible to the naked eye. The leaves are narrower than normal and the plant will gradually become less vigorous.
There is no cure, chemical or non-chemical, for eelworm. Remove the plants and burn them, roots and all.
Below we list the key strengths and weaknesses of Heleniums.
|HARDY||(to -25°C / -13°F)|
|SANDY SOIL||No unless improved|
|POT / CONTAINER||No|
|FLOWER TIME||Mid summer to mid autumn|
PICTURE GALLERY OF HELENIUM VARIETIES
There are literally hundreds of varieties of Heleniums, our picture gallery shows some of the ones we recommend. Click here to see the Helenium picture gallery.
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