Growing Sweet Peas in Pots with Tall Supports: A Complete Guide

Illustration of flowering sweet peas climbing canes in a large container

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Growing sweet peas (Lathyrus odoratus) in pots with tall supports allows you to introduce fragrance and height to balconies, patios, or small courtyards where ground space is limited. Because annual sweet peas are climbing plants that typically reach heights of up to 2m, the success of container growing depends on providing a stable, tall structure and a nutrient-rich environment to support their rapid summer growth.

Table of Contents

Selecting the right pots and soil

Sweet peas require fertile, well-draining soil and sufficient root space to prevent them from becoming stunted. While dwarf varieties exist, climbing sweet peas need deeper containers to remain stable once they reach full height.

Pot size: Choose a deep, broad container with enough volume for the number of plants. A heavy base helps, but does not guarantee stability: shelter and secure installation of a tall support are still necessary.
Compost: Use a high-quality, peat-free potting compost. Use seed compost in nursery pots for germination, then an appropriate potting compost in the final display container.
Drainage: Ensure pots have drainage holes to prevent waterlogging, as sweet peas can rot in very wet, heavy soil.

Choosing and installing tall supports

Since most annual sweet peas climb to approximately 2m, your supports must be tall enough to accommodate this growth while remaining securely anchored in the pot.

Support types

Bamboo canes: Slender and strong, these are ideal for individual plants or for creating a ‘wigwam’ structure.
Trellis or obelisks: These provide a wider surface area for tendrils to grip and are particularly effective for creating a dense wall of flowers.
Pea sticks: Natural, twiggy supports that provide many small attachment points for the plant’s tendrils.

Installation tips

Insert supports into the pot at the time of planting. If you push them in after the plant has grown, you risk damaging the root system. For a wigwam effect in a large planter, place several canes at the edges and tie them together at the top.

Sowing and planting in containers

You can sow sweet peas in autumn (October-November) or spring (late January-April). Pot-sowing is generally more reliable than direct sowing in the ground.

Preparing the seeds

Follow the seed packet first. Fresh seed can usually be sown without cutting its coat. If using damp tissue to pre-germinate seed, inspect it daily and plant as soon as it swells or the root appears; handle the tiny root carefully and discard mouldy seed.

Sowing steps

Fill 9cm pots with peat-free seed compost.
Sow seeds individually or plant several seeds in a larger nursery pot, spacing them 2-3cm apart.
Cover with 1cm of compost and water.
Maintain a temperature of approximately 15°C.
Once seedlings reach 3.5cm, transplant them into individual 9cm pots if they were sown in groups.

If sown indoors, harden off seedlings for 10-14 days before moving them to their final sunny position to prevent cold shock.

Training for a flowering display

To ensure the plant grows vertically and produces a high volume of flowers, guide young shoots towards their support. Cordon training is optional and is mainly useful for specialist cut-flower growing.

Pinching out

When spring-sown plants reach 7.5-10cm in height, pinch out the growing tip using your thumb and finger. This encourages the plant to produce strong side-shoots, resulting in a bushier plant with more flower sites.

Creating cordons

For those growing sweet peas for cutting or exhibition, the ‘cordon’ method is used to maximise bloom size. Select the strongest single shoot and pinch out all tendrils and side-shoots as they develop. This forces the plant to concentrate energy into the flowers on the main stem. Cordons can often grow taller than the standard 2m height.

Tying-in

While tendrils naturally grip supports, new shoots should be tied to the canes or trellis using garden twine or sweet pea support rings to prevent them from breaking or wandering.

Container maintenance and feeding

Plants in pots dry out faster than those in the ground and deplete nutrients more quickly.

Watering and feeding

Check potted sweet peas daily during dry weather. Water deeply to ensure the entire root system is wetted. To encourage flowering, apply a high-potassium liquid fertiliser, such as a tomato feed, weekly or fortnightly, following the manufacturer’s dosage instructions.

Deadheading

Regularly pick or remove dead flower heads. This is critical for annual sweet peas, as allowing many seedpods to mature can shorten the flowering season. Sweet peas are ornamental: their seeds and pods are not edible garden peas.

Diagnosing common pot problems

Container-grown sweet peas are susceptible to a few specific issues that can be identified by the foliage.

Symptom	Likely Cause	Management
Grey leaf covering	Powdery mildew	Improve watering; avoid drought stress.
Scorched foliage/bud drop	Temperature stress	Keep well-watered; avoid wetting foliage in heat.
Weak, leggy seedlings	Insufficient light/excess heat	Move to a cooler, brighter location.
Distorted leafy shoots	Leafy gall	Check against specialist leafy-gall guidance; simply trimming shoots may not remove the underlying infection.

Useful products for this job

The links below open Amazon UK product searches. Check the exact item, seller, current price and compatibility before buying.

Bamboo canes: Essential for providing the tall vertical support required for climbing sweet peas. Match the cultivar’s expected height, allow for the buried portion, and check cane thickness and anchoring. Cap exposed tips near eye level. Search Amazon for Bamboo canes.
Peat-free seed compost: Necessary for the initial sowing and germination phase of sweet pea seeds. Choose a peat-free medium suitable for seed sowing; suitable multipurpose compost can also be used where the packet permits. Search Amazon for Peat-free seed compost.
High-potassium liquid fertiliser: Used to encourage flowering and fruit/bloom production in container-grown plants. Check for high potassium (K) content on the NPK label. Search Amazon for High-potassium liquid fertiliser.

Related garden guides

Sources and further guidance

Guidance researched in September 2026. The feature image is an AI-generated illustration. Product guidance is based on published information, not hands-on testing.