A guide to growing cut flowers

Last year we split our allotment plot in half, with one side growing cut flowers and the other vegetables. I always loved the idea of growing your own flowers to brighten up your home or to take a freshly picked bunch to friends as a gift.

Planting for a cutting garden
Planting for a cutting garden

I’ve collated this blog post to get you started on how to create your very own flower shop in your back garden. I’ve included a cut flower plant plan, a step-by-step guide to sowing seeds and in particular some tips for planting Sweet Peas, Dahlias, Scabiosas, Antirrhinum, Ammi Majus, Cosmos, Larkspur and Bells of Ireland which will give you blooms from spring through to autumn as well as rules for picking.

Choosing the right spot

You’ll need to choose a sunny area in your garden or allotment plot that’s protected by strong winds which can affect the stems of the plants. Ensure the soil is well-drained, weed free with a fresh layer of compost before planting to get your plants off to a thriving start.

Making a plan

You need a rough plan of what you want to grow, when you want it to be ready and how you’re going to grow plants (from seed or by purchasing younger plants). Sowing seeds is a lot more cost-effective and gives you much more choice but both work. For our cut-flower area, I decided to grow the following. (Details on how to sow seeds can be found further down):

To help you decide what you want to grow, think about what time of the year the plants are going to be ready for picking and work backwards. Plot when each variety needs to be sown, planted and cut. You will want to stagger sowing and planting so you have a constant supply all summer.

Cut flowers planting plan

Cut flowers planting plan
Cut flower planting plan for producing blooms from spring through to autumn

Sowing seeds

Growing from seed; a step-by-step guide:

  1. Moisten your potting soil until it’s thoroughly damp
  2. Fill seed flats/pots to the top with soil, tapping firmly against the table as you go so that the soil settles in and there are no air pockets
  3. Label tray of pot with the name of the variety and the date planted
  4. Refer to the seed packet for planting depth. Make a hole for the seed in each cell or pot using a pencil
  5. Drop 1 or 2 seeds in to each hole
  6. Add a light dusting of seed-starting mix
  7. Set freshly sown trays or pots in tubs with an inch of water at the bottom – remove once soil surface is evenly moist (no longer than an hour)
  8. Cover trays or pots with clear plastic dome and set on a 21C heat mat or in a warm corner of the house. Seeds will usually sprout before you need to water again, but check the soil for moistness after 2 to 3 days and bottom water again if dry
  9. Check trays and pots daily. Once the seeds have sprouted, remove the plastic dome lids and move the trays or pots to a spot with bright light/greenhouse. The very first leaves are called cotyledons; those that appear after are known as true leaves. Water until true leaves appear
  10. When soil starts to become dry water every day or two with a very gentle spray/can. As young plants grow, they need to be fed. Add a small amount of liquid seaweed and fish emulsion and drench weekly.
  11. When your seedlings begin to outgrow their trays/pots, at about 2 inches tall, repot them into larger containers – or if warm enough start transitioning them outside.
  12. It’s important to harden off young plants before putting them out in the garden; otherwise they will be shocked by the sudden change in temperature. To do this, set trays/pots in a sheltered spot outside increasing the amount of time they’re out there. Start with 2 to 3 hours, then increase slowly over the course of a week or two. This helps young plants acclimatise better to temperature fluctuations.

Sowing specific cut flower varieties

Sweet peas

With their beautiful scent, gorgeous blooms and an abundance of flowers produced throughout the summer, sweet peas make great cut flowers. These annual climbers produce lots of roots so the more space you give them at the beginning, the better they will grow.

Sweet pea cut flowers
Sweet peas
  • Soak seeds for 24 hours before sowing.
  • Allow for two seeds per pot or see tray hole and cover with a seed propagator lid to create the ideal growing environment. Keep pots moist.
  • Pinch out tips when plants have four pairs of leaves – ‘Pinching’ is a type of pruning that encourages plants to branch out along the stem to become fuller and more bushy.
  • Once they’re ready to go into the ground, keep them tied to trellis for straight stems.

Scabiosa stellata

Scabiosa is a cut-and-come-again bloomer. The blooms appear so profusely that you’ll still have plenty of colour in the garden after you’ve picked your flowers. Cut flower stems can be harvested, when the flower shows colour. Put the stems in warm water immediately. Vase life: 8 to 10 days.

Scabiosa cut flowers
Sarah Raven scabiosa stellata
  • Sow in pots or trays of moist seed compost and cover with a very fine sprinkling of compost or vermiculite.
  • Keep soil moderately moist during germination, which takes around 7 to 10 days at temperatures between 15 to 20°C. When large enough to handle, transplant the seedlings into small pots to grow on.
  • Acclimatise to outdoor conditions for 10 to 15 days before planting out after all risk of frost 15cm apart.
  • Only water in an extended drought and do not apply large doses of fertiliser as flowering will be suppressed. Deadhead to prolong flowering and to encourage new flower buds.

Antirrhinum/snapdragons

Loved by bees, these annuals make excellent cut flowers. Regular pruning can encourage new growth and extend the blooming period from summer through to autumn.

Antirrhinum cut flowers
  1. Using a damp tooth pick, pick up just 1 or 2 seeds and place them into a cell of your seed tray, then cover with a light dusting of vermiculite.
  2. Once plants have 3 sets of true leaves, transplant them to the allotment/garden.
  3. To increase the number of blooms, pinching is recommended. When plants have 5 sets of true leaves, snip off the top leaving 3 leaves. Because pinching delays flowering by 2 to 3 weeks, do this with half of your plants.
  4. Shortly after pinching put a 30cm high layer of flower netting down to support the stems. As they lengthen they can grow through the netting
  5. Keep picking (not to the ground but to above a pair of leaves) and these will keep flowering for months at a time.
Snapdragons

Ammi Majus

Dainty white delicate flowers with lovely green foliage, Ammi Majus makes a great flower for padding out and filling a bouquet. They are easy to grow from seed. Ensure that you stake them early and use netting to support their stems. Pick them when about 80% of the flowers on a stem are open.

Ammi Majus cut flowers
Ammi Majus

Larkspur

With tall long blossoming stems and available in a variety of blues, purples, pinks and white, Larkspur is another cut flower which is great for adding height to a vase.

Larkspur cut flowers
Larkspur
  1. Freeze seeds for 7 – 10 days before sowing.
  2. They are best sowed directly into the ground once all risk of frost has been eliminated.
  3. Harvest once a third of blossoms are open on stem.

Bells of Ireland

These beautiful apple-green bell-shaped blooms produce a vanilla-like scent and look great fresh or dried.

  1. Freeze seeds for 7 – 10 days before sowing.
  2. Stake when the stems are 6 inches tall.
  3. Harvest once green bells start to form along the stem.

Cosmos

Cosmos are lovely pollinators and are a great cut-and-come-again flower. The more you harvest them, the more they produce.

Cosmos cut flowers
Cosmos
  1. Sow under cover in mid-spring and plant out after last frosts, or direct sow early May.
  2. Pinch out tips at 15-20cm to encourage bushier plants.
  3. Cosmos need staking and ensure that you deadhead regularly.

Dahlias

Dahlias are one of the best for cut flowers: the more you harvest, the more they keep coming. Ensure you choose tubers that are recommended for cutting and reach at least 1m high.

Dahlias cut flowers
Dahlia ‘Café au Lait
  1. Plant out at 45cm apart in double rows a good 1.5m apart when the ground has warmed (15.5C) normally 2 weeks after the last frost. (Mulch or cloche if foliage appears before frosts are over).
  2. Pinch out their growing tips when they have reached 8″ tall.
  3. Slugs and snails are their enemy so ensure you put down bait 2 weeks after planting or as soon as you see foliage emerging.
  4. By midsummer, ensure the plants have sturdy posts
Freshly picked cut flowers

Rules for picking flowers

Fresh flowers from your cutting garden can last up to three weeks if you look after them.

  • Always pick first thing in the morning when water reserves in the stem are highest, after a cooler night. Store flowers in water immediately.
  • The more you pick, the more the flowers will bloom but be careful not to cut the stems too close to the ground, retaining the side shoots for the next batch to produce.
  • Clean the stems and remove any foliage likely to be placed in water, otherwise they will rot. Trim the ends by at least 2cm at a 45 degree angle.
  • Avoid placing your arrangement in direct sunlight, draughts near heat or next to fruit bowls.

Enjoy! x

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