Helianthus Shock-o-Lat

Sunflowers - Grow Guide

Find out all you need to know about growing helianthus, or sunflowers, in this grow guide.

The sunflower is one of the nation’s most-loved flowers. The single, semi-double or double flowers grace our gardens in summer. Although largely yellow flowers, rusty red, green and white-flowered forms are also available. Plants can either be annual or perennial.

The annual types are often grown as part of a race to see who can grow the tallest sunflower. Choose your sunflower variety carefully as some will grow 50cm, while others up and over 3m.

Discover how to grow sunflowers, plus the biggest varieties to grow, below. 

J F M A M J J A S O N D
Sow
Sow
Yes
Yes
Yes
Plant
Plant
Yes
Yes
Yes
Flowers
Flowers
Yes
Yes
Yes
Yes
CutBack
CutBack
Yes
Yes

Planting position

A sunny position is favoured – the annual flowers will always grow towards the sun. Annuals are happy to grow in pots of multi-purpose compost, whereas perennials prefer a border setting, planted in the ground. Avoid very small pots as plants will suffer if they are left to dry out.

If planting annual types in garden soil they prefer a neutral or alkaline soil and one that is humus-rich and well-drained. 

Planting technique

Annual sunflowers can be sown directly into their planting position as they're hardy annuals. Sow in May in a weed-free soil and water well. If you miss the sowing time in April or May you will be able to buy potted plants in June.

Perennials plants can be quite enthusiastic growers, so ensure you give them plenty of space at the back or middle of a border. Feed with a general purpose fertiliser in spring.    

Propagation

Grow hardy annual types from seed by sowing directly into the garden in April or May.

If you would rather sow them into pots then plant one seed per 7.5cm pot. Push the seed 1.5cm into the multi-purpose compost and water in. Cover pots with a clear plastic bag and place them in a cool but bright place. Plant out young plants after the last frost. If you have any seed left over don’t be tempted to eat them – seed in packets may have been treated. Buy ones to nibble from the health food shop instead!

Perennial types are easily divided in autumn or spring. Simply dig out a section of a mature clump and pot on. 

Troubleshooting

Sunflowers are trouble free but young seedlings are susceptible to slug and snail damage. If you are only growing a few annual sunflowers try placing a copper garden band around each seedling. When the slugs meet the band they get what is similar to an electric shock. 

Care

Annual sunflowers need plenty of water. They’re helped with a feed of tomato feed just before flowering. Don’t allow plants to dry out as very tall varieties will have a job to recover.

Very tall varieties may need the support of a garden cane – especially when growing in an exposed position.

After flowering leave the faded flower head intact so the birds can feast on the seeds. Once they have eaten their fill pull out the entire plant and put it on the compost heap.

Perennial types need very little care. Simply cut plants right down to ground level in autumn. 

Watering can

Leave the seeds for birds

The large seeds of the annual sunflower are adored by garden birds. Don’t deadhead plants. Allow the seed to ripen and be feasted on by our feathered friends. You could also use the seeds to make a pumpkin bird feeder.

Helianthus 'Yellow Queen'
Helianthus 'Yellow Queen'

Sunflowers to grow

  • Helianthus annuus ‘Russian Giant’ – this is a real cracking annual with flower stems reaching as high as 3m. A traditional yellow flower from July-September. A real race winner! 
  • Helianthus annuus ‘Velvet Queen’ – coppery red flowers from July to September from this popular annual. Reaches 1.8m
  • Helianthus annuus ‘Teddy Bear’ – an annual with large pom-poms of double yellow flowers from July to September. Height 50cm
  • Helianthus giganteus – large single yellow blooms held on 2m long stems from June to August

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