In this article, we will discover how to grow the firm favourite of Helianthus in containers. To the botanist, it is a Helianthus, but to most gardeners and children it is a sunflower, large flower heads that follow the sun. You may enjoy the large flower heads but you wonder if they can be grown in containers? Worry not as this article will address this issue.
First, if you want to grow a sunflower in a container forget about tall giants, they simply look silly and out of proportion. Instead grow smaller, dwarf varieties less than 1m in height or grow tall varieties in substantial sized pots (such as 30 litres or more)
Second, you need to grow sunflowers in containers in the right growing conditions. Get it wrong and you will get any sunflowers.
A rule of thumb is that if the variety you grow is less than 60cm in height, then use a container that has a diameter of 30cm or more. For large sunflowers, use a container that holds more than 30litres of compost and offer a lot of support.
Ultra dwarf varieties can be grown as part of window box display with other annuals that come in vibrant oranges and reds. Varieties to go are ‘Music Box’, the bronze flowered sunflower ‘Sundance Head’, or the double-flowered pompon-like ‘Teddy Bear’.
GROWING SUNFLOWERS IN CONTAINERS
Sunflowers are easy to grow from seed, otherwise, you can find ready-grown plants from garden centres or online shops. It is a great project to get children involved. From seed you have much more choice from height to grow to, what colour the flowers come in, be it atypical yellow, vibrant reds, subtle greens or even whites.
Annual sunflowers, normally bloom from 11 to 18 weeks, and if you stagger the sowing, you can have plants in constant flower throughout the summer. Although we will be talking about annual sunflowers, there are perennials like Helianthus tuberosus (Jerusalem Artichoke) that will not do well in containers, as they will need plenty of growing room.
GROWING SUNFLOWERS FROM SEED
First, choose your variety carefully paying particular attention to height and flower colours. Fill a 7.5cm pot with a good quality multipurpose compost and make a hole with your finger up to a depth of 1.5cm. In the hole, place the large seed.
It is best to only plant one seed per pot as they will be difficult to separate as they grow very quickly.
Cover the pot with some cellophane wrap and place it in a greenhouse if you have one or a bright window if you do not. After a week or so, the sunflowers seed should germinate.
At the end of May, your plant should be tall enough to be planted outside after it has been hardened off.
You will then need to select the correct container size as demonstrated earlier. Make sure it has plenty of drainage holes. Fill the pot with good quality multipurpose compost after placing a 1cm layer of gravel at the bottom. Dig a hole that is slightly larger than the root ball of the plant you have reared or bought. Place the plant in the hole so that the top of the root ball is at the same level as the top of the compost. Backfill with the growing media, ensuring that gaps remain is filled with more compost. Firm the plant in and water well.
PLACE THE CONTAINER AND SUNFLOWER IN A SUNNY SPOT
Place the container where it will get at least 6 to 8 hours per day. Watering is very important as they are thirsty plants. Water when 2.5cm below the top of the surface of the compost feels dry to the touch. Water frequently in heatwaves but less when it rains.
As the flowers start to grow, you will need to give a weekly feed of liquid balanced fertilizer. Switch to a high potash fertilizer once the flowers start to appear at the same rate.
If the plant is very tall, you will need to stake it with a bamboo cane, as otherwise, it will snap like a twig in the wind.
Leave the flower heads on the plant in late summer, so that the birds can feed on the seeds and that you will have enough to harvest some seeds for planting next year. In autumn thrown the plant in a compost heap.
PESTS AND DISEASES
Sunflowers tend to be a favourite of slugs and snails, especially whilst young. To avoid this, you can let them grow quite tall before planting them out and by protecting them with slug pellets or wool deterrent matting.
If you do not water too much, it can lead to powdery mildew, which can be treated with a suitable ornamental systemic fungicide.
VARIETIES TO GROW
The following varieties are recommended to grow based on Helianthus annus:
‘Dwarf Yellow Spray’ is a dwarf variety growing up to 60cm, which has multiple heads of yellow flowers with dark centres.
‘Brown Eyed Girl’ is a 60cm tall variety with yellow flowers, multiple heads and very dark centres.
‘Elite Sun’ is a plant to grow in large containers where yellow flowers with dark centres and grows up to 1.2m high.
‘Little Sorry’ is another plant that can be grown in large containers, where it will grow up to 1.2m. It has a frilly head with chocolate centres.
‘Ms Mars’ is a plant that has rosy-pink to purple petals with lighter tips and chocolate centres.
‘Teddy Bear’ is a dwarf variety of sunflower, where it will grow up to 45cm in height and where fluffy, double teddy bear-like orange flowers appear.
‘Sunshot Gold Mixed’ is a short, 45cm tall, free-flowering, multi-stemmed variety. It can bear up to 20 double and semi-double, Chrysanthemum-like blooms that last a long time.
‘Solar Flash’ is a 50cm tall plant that produces multi-heads of gold and bronze flowers with chocolate coloured, pollen-free centres.
‘Irish Eyes’ is a multi-stemmed sunflower with attractive yellow flowers and an unusual green central disk, where it will grow up to 45cm tall.
‘Choco sun’ is a dwarf multi-flowering sunflower that grows up to 35cm in height and produces yellow blooms with chocolate centres.
Helianthus maximiliani ‘Early Bird’ is a perennial sunflower that grows up to 1m high. It produces multiple flowers with bright yellow petals and a scent that reminds you of chocolate.
In this article, we have discussed how to grow Helianthus in containers. As you can see they are such delightful flowers to grow in containers to give much colour. It will also be used as a means of getting your children interested in gardening. Easy to grow from seed, many varieties to grow, and much fun to be had.
If you have any questions or comments to make on growing Helianthus in containers, please do so in the comment box below.
Happy Sunflower growing.