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Handy guide to plant sizes and simple growing instructions

Suttons plant sizes with labels

When you order plants online, you’ll often be given a choice of sizes. While all our plants are raised under the same controlled, high quality conditions, you can choose from several different sized plugs or skip straight to the biggest garden ready plants in pots. If you have the time and space to pot on the smaller plugs, they represent exceptional value for money. However, if you’re looking for a quick and easy shortcut, it makes sense to order strong 2 litre potted plants that are raring to go! 

Browse our full range of bedding plants to find the perfect blooms for your beds and baskets.

What sized plugs and plants are available?

Garden ready plants surrounded with cardboard and growing instructions
Garden ready plants get delivered with growing instructions
Copyright: ©T&M

Extra value plugs (approx. 3 – 6cm)

Grown using an innovative cartridge plug system, these young plants have an extra strong root system. Browse extra value plugs here.

Value plugs/Postiplugs (approx. 5 – 9cm)

A popular size for good reason. These plant parcels fit through most standard letterboxes. Size 5-9cm. Browse value plugs here.

Super plugs/Jumbo plugs (approx. 5 – 11cm)

For the best performance, we recommend that you grow your super plugs on further in 11cm pots or their final planting containers, maintaining a minimum temperature of 13-16 ̊C (55-60 ̊F). Allowing your super plug plants to establish in this way before moving to their final position outdoors pays dividends later in the season. Browse super plugs here.

Garden ready plugs (approx. 10 – 15cm)

While these plugs are ‘garden ready’ always make sure that all risk of frost has passed before you plant them out. For planting directly into the ground, ensure that the soil has been dug over and lumps broken down. Add a good handful of compost if your existing soil is poor. Once planted, don’t forget to give your plants a drink and protect them from slugs and snails. Browse garden ready plugs here.

9cm potted plants (plants from 7cm)

These large potted plants offer excellent value and the ultimate convenience! Plant them out or pot them on for the best results.

2 litre potted plants

These well-established plants in 2L or 3L pot sizes can be planted straight into their final positions. Browse 2 litre potted plants here.

Please note: Our Extra Value and Value plug plants trays contain extra cells over and above the stated quantity. You’ll normally receive a few extra plants, even if some of the cells are empty.

What to do when your plants arrive

Plug plants arriving in letterbox-sized parcel
Check your plants over once they arrive
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  • Carefully unpack your plants and check that the compost is moist.
  • If the compost is dry, water carefully and allow it to drain.
  • Stand in a light, warm place, and then follow the growing instructions as soon as you can – provided they’re kept moist, your new plants can usually wait for up to 3 days for planting.
  • Your plants have been grown under ideal conditions, and inspected by one of our experts prior to packing and despatch. However, if they’ve been damaged or delayed during delivery, please contact us immediately.

How to care for your plug plants in the garden

Multicoloured petunias in containers
Petunia ‘Double Orchid’ will flower until the first frosts with a little care and attention 
Image: Petunia ‘Double Orchid’ from Suttons

To achieve a stunning display that lasts all summer long, check your plants to make sure that they have adequate water and feed them regularly. When planting in containers, mix a slow-release fertiliser plus some water retaining crystals into the compost. They will then need less attention throughout the summer. 

Try to water below the foliage canopy of the plants to reduce marking and damage to the flowers. Removing the dead and damaged flower heads will not only improve the appearance of the plants, but will also prevent the plant putting energy into seed production and ensure that more flowers are produced.

Brightening up your garden, starting a veg patch or taking on an allotment? Buying trays of plug plants gives you a strong start without breaking the bank. If you’re looking for practical guides to growing fruit, veg, flowers, shrubs and trees, visit our ‘expert advice’ articles for professional tips.

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15 thoughts on “Handy guide to plant sizes and simple growing instructions”

  1. Julia Zouch says:

    I’ve received my callistmon Inferno plant, It’s a nice sturdy little cutting and has started to produce new growth quite rapidly. I have it on a sunny west facing windowsill at present as it is so small. When should I pot it on, and how soon should I pinch out the tips?

  2. Ken Baldwin says:

    I would hope many thousand’s of people will start growing their own fruit and vegetables now that the cost of many products has risen and,no doubt continue to rise.It’s not that much hard work if you put your mind to it and the rewards are tremendously spirit-lifting in difficult times!

  3. Helen Green says:

    Hi I had a 2 litre pot of allium delivered what do I do plant them out now or put in greenhouse

  4. Katie Brunt says:

    Hi Mark, pot up echinacea plants and grow them on in frost-free conditions until large enough to transplant outdoors. Gradually acclimatise plants to outdoor conditions over a period of 7 to 10 days prior to planting out in borders. Grow echinacea plants in a sunny or semi-shaded position on moist, well-drained soil. Coneflowers prefer deep, fertile soil and will benefit from the addition of some well-rotted manure or garden compost to the soil, prior to planting. We hope this is helpful to you!
    Best regards,
    The Suttons Team

  5. mark smith says:

    I’ve received my Echinacea (Cone Flower) Nectar Pink plugs, whats the best way forward for them to grow on, plant into larger pots, leave inside over winter or place them outside?

  6. Katie Brunt says:

    Hi Jacqueline, the hydrangea will benefit from either potting on into a container of minimum size 30cms diameter and 10 litre capacity or planting out into a border. In a container use some John Innes No 3 compost and begin feeding after 4 weeks with a general-purpose fertiliser. In a border incorporate some well-rotted manure or garden compost when planting. Keep moist and water regularly during the first year. We hope this is helpful to you!
    Best regards,
    The Suttons Team

  7. Jacqueline Martin says:

    Hi I’ve just received my 1litre hydrangea plants, what is the best way to plant them on now?

  8. Katie Brunt says:

    Hi Elisabeth, Broad beans should be planted outside in the winter but if the ground is frozen or waterlogged it would be best to pot them up and keep them in a cold greenhouse if possible. Once conditions improve they will happily thrive outside and withstand frosts. We hope this helps you and good luck with your broad beans!
    Best regards,
    The Suttons Team

  9. Elisabeth Tribe says:

    I have just received some broad beans Aquadulce Claudia – in beautiful condition, thank you. Should I pot them on also and wait until risk of frost has passed before planting outside?

  10. Suttons says:

    Hi, thanks for getting in touch. Planting is best done soon after delivery but if this is not possible the trees will be fine in a cool but frost-free place for a few days. Perhaps an unheated shed or garage. When you do come to plant, soak the roots first in a bucket of water for about 2 hours. The planting hole needs to be deep enough for the old soil mark to be at ground level or just slightly below. And wide enough to allow the roots to spread out. Refill the hole and gently tread down the surface. Water thoroughly and repeat often.

  11. miss v.a.fawcett says:

    just received a bear root bush pear tree. please advise on planting.

  12. David Harris says:

    Very Interesting blog. Thanks for Sharing

  13. Harry Chapman says:

    I have just received my order of the Sweet William plugs and planted them into pots. They are now in my green house and will stay there until next year, but do they need to be kept at any minimum temperature?

  14. Hi Sue, thank you for ordering the Agastache plugs.

    They’ll be ok in a cold frame but we’d suggest you bring them in of an evening.

    Suttons Gardening Grow How team.

  15. Sue Bickley says:

    I have just received an order of AGASTACHE plug plants. I know I need to pot them on, but do they need to be protected from frost. if so would a cold frame be enough or do they need to be kept inside until the weather is warmer.
    Many thanks

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