How to grow Cuphea
Also known as the cigar plant or false heather depending on the species, cuphea is a large genus in the same family as loosestrife and pomegranate (lythraceae). Of the 250 plus species, most originate from warm to temperate regions of Mexico and central and southern America. Just a handful of these are cultivated widely, grown for their profusion of flowers which often lasts from spring until the first frosts. Many species are sticky to the touch and produce long, tubular flowers (hence ‘cigar plant’), though a few bear unusual wheel or windmill-shaped blooms. They tend to be fiery, almost neon shades of red, orange, or yellow, though the opposite side of the colour wheel is also represented with a few pale pastel purple and pink forms.
Cuphea has a small, dense, self-contained habit which makes it easy to grow amongst other plants. It is also valued for its ‘self-cleaning’ nature, meaning the flowers shed naturally and neatly without the need for deadheading. Cuphea can be an annual, perennial, or shrub depending on the species, though in our UK climate all tend to be treated as an annual regardless.
Key Information
Position
Soil Conditions
Hardiness
Where & when to plant Cuphea
Position - Outdoors: a warm, sunny spot is best. Some shade will be tolerated though is likely to mean fewer flowers and slightly leggier growth. Indoors: bright though with shade from hot midday sun.
Soil - Any moderately fertile soil
Flowering Period - Potentially spring through to autumn
Hardiness - Tender, usually rated H2, i.e., perishes below 1-5°C
Cuphea hails from warmer climes than ours and can only live outside in the UK once all risk of frost has passed. This varies from region to region, though tends to be mid to late May. If your plants arrive before it is safe to go outdoors, keep them in a bright, frost-free environment until the time is right. A greenhouse, conservatory, coldframe, or sunny porch or windowsill are all ideal. Just make sure you don’t let them dry out! Small plug plants are best potted up into 9cm pots if they’re going to spend time in a ‘holding zone’ like this.
Another important thing to note with tender plants such as cuphea is the need to gradually harden them off, rather than suddenly move them outside. Slowly toughening them up in this way reduces the chances of them going into ‘shock’, which can severely check growth.
We recommend taking the following steps, starting around three weeks before the final move:
Week 1 – wrap in two layers of fleece and place outside during the day only (moving back into a warm, protected environment at night).
Week 2 – as week 1, though this time with the fleece reduced to one layer.
Start of week 3 – now with no fleece. If it’s warm enough you can leave outside at nighttime too, though reapply the fleece for this.
End of week 3 – leave outside completely uncovered for a couple of days/ nights before planting out as follows.
Alternatively, use a coldframe opened in gradual increments over a similar time period.
When it comes to choosing a spot, cuphea is ideal for a summer container display, or as a bedding plant in borders. Most UK gardeners treat cuphea as an annual, though evergreen perennial species may also be grown as houseplants (given them a bright, moderately humid spot such as on a bathroom or kitchen windowsill) and kept going for a few years. Cuphea ignea and Cuphea hyssopifolia are suitable candidates for this.
How to plant Cuphea
- For planting in the garden, dig the soil area removing any large stones and weeds and breaking up any lumps. Mix in some organic matter such as manure or garden compost. Rake level and firm with your heels. Rake level again.
- Water plants well and allow to drain before planting.
- Dig a hole twice the size of the root-ball.
- Place the plant in the hole, ensuring the top of the root ball sits level with the surface of the soil. Too low and the plant may rot, too high and the roots can dry out.
- Backfill with soil and firm in gently with your foot.
- Soak well with water.
- Mulch around the base with well-rotted organic matter.
- For planting in containers, first choose an appropriately sized pot. You may wish to grow your cuphea on its own in a pot, or as part of a larger, mixed container display. Either way, ensure there are plenty of drainage holes in the bottom.
- If you are using a large or heavy pot, it can be a good idea to fill and plant it in situ to save yourself the trouble of moving once full.
- Use a good quality potting compost with plenty of horticultural grit mixed in and, if not already present (check the labelling on the bag) some slow-release fertiliser granules.
- Start by partially filling the pot with compost; enough so that when placed on it the upper surface of the root ball is about 3cm lower than the top of the pot.
- Fill around the plant with compost, firming down with your fingers then adding a little more so it is held tight.
- Pick up the container (if you can!) and lightly tap on the potting bench or ground a few times to help further settle the compost around the plant.
- Soak well with water.
- A mulch with horticultural grit will look attractive and help to prevent a ‘cap’ or crust forming on the top of the compost (something container plants can suffer due to the artificial nature of their watering).
What to plant with Cuphea
For a glorious summer container display, we suggest pairing cuphea with other bedding plants such as diascia and a small fuchsia. A focal plant will top things off nicely; think along the lines of salvia, dahlia, canna, or a small cordyline.
How to care for Cuphea
Pruning and Deadheading
For a bushier, more floriferous plant, pinch back the growing tip in late spring. Simply nip the top off, taking it down to a lower pair of buds.
Deadheading is not required on this self-cleaning plant (see ‘Overview’).
If, like most gardeners, you intend to treat your cuphea as an annual, simply remove it to the compost heap at the end of the growing season. To keep evergreen perennial species as houseplants, some pruning in spring will help maintain a neat, compact appearance. The first time you do this, cut back any flowered stems to a couple of centimetres above the base. In subsequent years, prune to within a couple of centimetres of the previous year’s cut.
Watering
Like most bedding plants cuphea will tolerate drought to a point, though does best when watered regularly. In a container it can be watered freely during the growing season. It’s worth noting that containers can dry out very quickly, particularly in warm weather, and may need watering as often as every day.
Cuphea in the ground should be watered regularly for the first few weeks, and then in any prolonged dry spells after this.
Feeding
To get the most out of hungry summer bedding plants such as cuphea, regular feeding is a must – particularly when grown in containers.
In a container, cuphea should be potted in a good quality compost with slow-release fertiliser granules mixed in. These generally provide enough nutrients for around 6 weeks, after which an application of balanced liquid feed every 3-4 weeks can make a big difference to performance. Steer clear of high nitrogen feeds, as these will encourage excessive foliage at the expense of flowers.
In the open ground, mulch newly planted cuphea with well-rotted organic matter, i.e., a layer of manure or garden compost applied to the soil around the plant. As well as boosting the nutrient content of the soil, this has the added benefit of suppressing weeds and locking in moisture. After this, you can either leave the plant to its own devices (fine on healthy, fertile soil), or apply a balanced liquid feed as above (beneficial on poor or sandy soil).
Cold Protection
Cuphea will not survive a UK winter outdoors. Either remove to the compost heap or overwinter indoors as a houseplant (perennial species only).
Pests and Diseases
Aphids and whiteflies can be a problem on cuphea. While unsightly, these are part of a balanced garden ecosystem, and the best approach is to leave them to their natural predators (e.g. birds, ladybirds, wasps, frogs). When numbers are so large, however, that their feeding starts to inhibit and disfigure growth, you may feel it necessary to take action. Regularly blasting off with a hose or wiping away with a cloth or piece of kitchen paper can help to keep numbers down without harming beneficial organisms.
How to propagate Cuphea
Perennial species are best propagated by softwood cuttings:
- In the morning on a day in late spring (plants are more turgid at this time and less likely to wilt during the process), take 10cm cuttings from the soft tips of new, non-flowering shoots. Snip off just above a bud using sharp, clean secateurs.
- Place in a clean plastic bag in which to transport the cuttings back to a potting bench or garden table.
- Fill a container with a well-draining compost mix.
- Trim the end of the cutting to just below a node (point at which leaves grow).
- Remove the lowest third of the leaves and pinch off the soft tip.
- Insert the cuttings into the compost and water lightly. Several cuttings can be put in the same container if there is enough space to do this without them touching.
- Place in a propagating unit with bottom heat if you have one, or covered with a plastic bag on a warm windowsill if not (out of direct sunlight). If using a plastic bag, remove it a couple of times a week for around ten minutes. This will ensure the cuttings remain well-ventilated and don’t rot.
- Keep the cuttings misted and occasionally watered until they root. You will know this has happened when roots emerge out of the bottom of the container.
- Gently remove rooted cuttings and pot them into individual pots. Grow on in a protected environment such as a conservatory, greenhouse, or that windowsill again, before planting out as above.
* Many plants carry Plant Breeders Rights and cannot be propagated for commercial purposes.
FAQ
Is cuphea easy to grow?
Very much so. This is a maximum flower/ minimum input kind of a plant. All it needs is sunshine, water, and a bit of feeding.
Can cuphea grow in shade?
It can grow in some light shade, though not as well as it will in full sun. Deep shade is to be avoided.
Is cuphea a perennial?
This depends on the species! See ‘When and where to plant cuphea’ for more information. For most of us this is irrelevant anyway, as we tend to treat them as annuals regardless.
