How to grow Rudbeckia
Rudbeckia have daisy-like flowers that provide a blaze of colour in late summer. They are generally low maintenance, have a long flowering season and are good for wildlife. The perennial types are usually yellow but there are other flower colours available, with the annuals that usually raised from seed offer blooms in shades of orange, dark red or brown.
- Rudbeckias flower between late summer and autumn
- Thrives in sun
- Grow well in most soils
- Suitable for borders, containers and prairie-style plantings
- Heights range from 25cm (10in) to 3m (10ft)
- Many are perennials, lasting many years
- Single flowered rudbeckia are good for pollinators
- Seedheads are attractive in winter
All you need to know
The popularity of this genus is well deserved; it is easy to grow, lends itself to different planting styles, flowers for a long time, and is good for wildlife.
When selecting the right one for your garden, bear in mind the following:
- Most species grown in the UK are hardy herbaceous perennials. The main exception is R. hirta which is very short lived and not reliably hardy, so it is usually grown as an annual from seed
- If you want to grow an annual for summer bedding, cut flowers, containers or for borders, choose a cultivar of R. hirta
- Rudbeckias vary a lot in size. R. hirta ‘Toto’ reaches about 25cm (10in), whereas R. laciniata can grow to 3m (10ft). Tall types will benefit from staking or shortening using the pruning technique of the Chelsea chop
- Most rudbeckias grow in easily manageable clumps, but R. laciniata has vigorous rhizomes (horizontal underground stems) that make it better suited to larger gardens else you'll need to lift and divide clumps regularly to keep them in check
- All types like a sunny spot and they will struggle if the soil dries out in the growing season. R. hirta and R. fulgida var. deamii are slightly more tolerant than most of dry conditions
- Although they like a moisture retentive soil, rudbeckias don’t like prolonged periods of wet soil in winter. R. maxima and R. subtomentosa are more able than most to withstand wet conditions
- Choose rubeckias that have received the RHS Award of Garden Merit, as these have been assessed and are known to perform well
Buy seeds for annual and perennial Rudbeckia from garden centres and online seed catalogues (eg. Chiltern Seeds, Thompson & Morgan).
Buy small plug plants in spring from garden centres or by mail order. You will need to pot plug plants into larger 9cm (3½in) pots and harden them off (process of toughening them up so they can cope with outdoor temperatures) before planting out after the frosts (typically late May/early June).
Many garden centres and nurseries stock rudbeckias. Use our Find a Plant Tool for stockists.
You will most likely see container-grown rudbeckias for sale, but it is possible to buy herbaceous perennials as bare-root plants. These will be available by mail order from autumn through to early spring. Buying bare-root plants is a good way to avoid the use of new plastic pots (see 'When to plant' section below).
When to plant
- Annual rudbeckias will need hardening them off (process of toughening them up so they can cope with outdoor temperatures) before planting out after the frosts (typically late May/early June).
- Perennial rudbeckias are best planted in spring (March to early May) while the ground is moist.
Container-grown perennial rudbeckias are sold throughout the year at garden centres and nurseries. Plant at any time as long as the ground is not frozen or waterlogged. If you plant in summer, they will require additional watering to keep the soil around the roots moist.
Plant bare-root perennial rudbeckias soon after delivery. If weather conditions are not favourable for planting it is important to ensure that the roots don’t dry out; you can stand the roots in a bucket of moist compost, or lay them diagonally in a shallow trench and back-fill with soil to cover the roots (heeling-in). Plant out as soon as weather conditions improve.
Where to plantRudbeckias grow well in full sun. They will flower okay in light shade, but the shadier the location the less they will flower.
Rudbeckias like a fertile soil that holds plenty of moisture in spring and summer. They don’t like to dry out, so if you have a light sandy soil dig in some well-rotted organic matter when planting (see How to plant section below), and add a 5cm (2in) layer as mulch to the soil surface in spring to help retain moisture around the roots.
Rudbeckias originate from the prairies of North America, so they are able to grow well in exposed windy areas. They also grow happily in sheltered conditions.
How to plantWhichever rudbeckias you plant, begin by preparing your soil. If you make your own compost, dig in a bucketful per sq m (per sq yd) to a spade’s depth over the planting area. If you do not make compost, buy any well-rotted manure or soil conditioner, and apply the same amount in the same way.
Whether perennials or annuals, the aim is to dig a hole in the prepared soil deep enough to take the rootball, place it in the hole, and then firm back the soil and water in well.
Rudbeckias in borders
Water well after planting. On free-draining soil or during prolonged dry spells, they will need additional water to keep the soil around the roots slightly moist, but not soggy. Aim to water well and occasionally, rather than little and often.
Rudbeckias in containers
These need more frequent watering than plants growing in the ground. Water as often as needed, which could be daily in hot weather. Try not to let the compost dry out, but don’t let it get waterlogged either.
Rudbeckia need little or no regular applications of fertiliser in most garden soils. Mulching plants in borders with well-rotted manure or garden compost each spring should be sufficient. If your garden soil is light and sandy, feed your Rudbeckia plants in spring when they start to come into growth with a general-purpose fertiliser such as Growmore, applying a handful per sq. m/yd.
For containers, use a liquid fertiliser, such as Phostrogen or seaweed feed, diluting according to the instructions on the bottle.
If you deadhead when flowers have faded this will encourage plants to keep flowering. To get the maximum amount of flowers from Rudbeckia grown as summer annuals, it is definitely worth regularly deadheading. You might choose to leave the seedheads for winter interest. Cones of Rudbeckia seedheads from perennials look attractive during the winter and provide food for birds.
Hardy rudbeckias grown in open ground should not need any protection.
Cultivars of Rudbeckia hirta may survive some winters in relatively mild parts of the UK, but in most gardens they will struggle to get through the winter. Cultivars of R. hirta are usually grown as annuals and composted in late autumn, but because they are short-lived perennials they could be overwintered in a light, frost-free environment (such as a frost-free greenhouse) and planted outside the following May/June.
Caring for older plants
Some of the tall species need staking. Alternatively, you can Chelsea chop tall Rudbeckia in May to reduce the eventual height and do away with the need for staking.
Like many herbaceous perennials, rudbeckias benefit from being lifted and divided every three to five years to maintain health and vigour. Lift and divide rudbeckias in early spring (March/April).
R. laciniata is vigorous and spreads by rhizomes; therefore, it might need lifting, dividing and reducing every two to three years to keep it in check.
Three to five years after planting a Rudbeckia, it will be ready to be dug up and divided into smaller clumps. This is an easy way to make more plants.
Rudbeckia can be propagated from seed; this is particularly useful for raising cultivars of R. hirta that are often used as annuals.
Sow indoors in early spring (March/April) in trays containing moist seed compost. Sow thinly and cover lightly with a thin layer of vermiculite or compost. Cover with glass, polythene or a propagator lid and keep at approximately 20°C (68°F) until seedlings appear.
Sow outdoors in late spring (May) in a prepared seedbed.
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