Choosing rudbeckias

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
  Gardeners often use the word variety when referring to a specific plant, but the correct botanical term is 'cultivar'. Whichever word you use, it means a distinctive plant or plants, given a specific cultivar name and usually bred to enhance certain characteristics, such as flower or fruit size, colour, flavour or fragrance, plant size, hardiness, disease resistance, etc. Additionally, it is worth knowing that, botanically, variety has another meaning - it refers to a naturally-occurring distinct plant that only has slight differences in its looks. For example, Malva alcea var. fastigiata differs from typical plants by having an upright habit.

  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 are creeping swollen root-like structures that are actually adapted stems. Roots, stems with leaves and flowers are produced along its length. See plants such as Anemone nemorosa, bamboo, canna, border iris.

  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 

RHS hardiness rating

RHS hardiness rating

Buying rudbeckias

Buy seeds for annual and

Perennials are plants that live for multiple years. They come in all shapes and sizes and fill our gardens with colourful flowers and ornamental foliage. Many are hardy and can survive outdoors all year round, while less hardy types need protection over winter. The term herbaceous perennial is used to describe long-lived plants without a permanent woody structure (they die back to ground level each autumn), distinguishing them from trees, shrubs and sub-shrubs.

Seedlings or young plants grown singly in small modules, with the advantage that they can be transplanted with minimal root disturbance. Bedding plants and young veg plants are often sold as plug plants of various sizes, with smaller ones requiring more aftercare. They usually need to be potted up and grown on indoors until large enough to plant outside.

plug plants

Perennials are plants that live for multiple years. They come in all shapes and sizes and fill our gardens with colourful flowers and ornamental foliage. Many are hardy and can survive outdoors all year round, while less hardy types need protection over winter. The term herbaceous perennial is used to describe long-lived plants without a permanent woody structure (they die back to ground level each autumn), distinguishing them from trees, shrubs and sub-shrubs.

perennials

These have been lifted from the ground while dormant, with little or no soil around their roots. Various plants may be available bare root, including fruit trees, hedging plants and some perennials. They are generally cheaper than plants in containers, but are only available in winter/early spring, while dormant

bare-root

Buying: garden centre plants

Buying: garden centre plants

Buying: mail order plants

Buying: mail order plants

How to choose healthy plants

How to choose healthy plants

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.   

Where to plant

How to plant

Perennials: planting

Perennials: planting

Watering

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.

Watering

Watering

Feeding

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. 

Deadheading

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.
 

Deadheading plants

Deadheading plants

Overwintering

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.

Perennials: staking

Perennials: staking

Chelsea chop

Chelsea chop

Perennials: dividing

Perennials: dividing

From division

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.
 

Perennials: dividing

Perennials: dividing

From seed

Rudbeckias are robust, easy to grow plants but they can suffer from powdery mildew and aphids.

If rudbeckias grown as annuals show scrawny poor growth, this usually indicates a lack of moisture. Water well in the summer to encourage good plant growth.