The Benefits of Container Growing

Rhubarb is a quintessential component of the British kitchen garden. Known for its tart flavour and vibrant stems, it is a hardy perennial that, once established, will return year after year. While traditionally grown in allotment beds or deep borders, growing rhubarb in containers is an increasingly popular method for those with limited space or paved outdoor areas. It allows you to move the plant to follow the sun during the variable British spring and controls the spread of its substantial root system.

Choosing the Right Planter

Rhubarb possesses a large, vigorous root system and requires plenty of space to thrive. A small pot will simply not suffice; the plant will become pot-bound, yield poor stems, and dry out too quickly. You need a container that is deep and wide, offering good drainage to prevent the crown from rotting during wet British winters.

When selecting a container, you have several stylish options that function well as a patio growing station. For a sleek, modern look, zinc square planters provide ample depth. These are available in matte black, matte grey, white, matte copper, or gloss black, allowing you to match the container to your existing garden furniture. If your aesthetic leans more towards the traditional or cottage-style garden, 65cm to 90cm diameter rustic whisky barrels are an exceptional choice. With their significant width, they offer maximum room for root expansion and come with faded silver rings, rustic rings, or painted black rings. Alternatively, for a natural, textured finish, up to 60cm wood square planters available in natural wood, black, or grey provide excellent insulation for the roots against frost.

Soil and Planting

Rhubarb is a "hungry" plant. It requires rich, fertile soil to produce thick, succulent stems. In a container, you should use a high-quality potting compost mixed with a soil-based compost (such as John Innes No. 3). It is highly beneficial to mix in generous amounts of well-rotted manure or slow-release organic fertiliser before planting.

The best time to plant rhubarb crowns is in autumn or early spring while the plant is dormant. Place the crown in the pot so that the tip of the growing point is just sitting at, or slightly below, the soil surface. Ensure the container has drainage holes; while rhubarb likes moisture, it hates sitting in waterlogged soil.

Care in the British Climate

Position your planter in a sunny spot, though rhubarb will tolerate partial shade. The most critical aspect of container care is watering. During the growing season (March to July), the large leaves act like an umbrella, deflecting rainwater away from the pot. Even in a rainy British summer, the soil in the pot can remain dry. Check the moisture daily and water generously during dry spells.

Feed the plant with a general-purpose liquid fertiliser every few weeks during the spring and summer to support vigorous growth. In winter, rhubarb requires a period of cold dormancy (chilling hours) to reset for the next year, which the UK climate naturally provides. However, because pots can freeze through completely, move the pot to a sheltered spot against a house wall or wrap it in fleece if temperatures drop significantly below freezing for extended periods.

Harvesting, Flowering, and Fruiting

Rhubarb is technically a vegetable, though we treat the stems as fruit. It does not produce "fruit" in the botanical sense; the harvest consists of the leaf stalks (petioles).

When to harvest: Do not harvest any stems in the first year after planting; this allows the plant to establish a strong root system. In the second year, take a light harvest. From the third year onwards, you can harvest fully from April through to July. Stop harvesting by mid-July to allow the plant to recharge its energy for the following year.

How to harvest: Grip the stem near the base and pull it with a gentle twist. Avoid cutting with a knife as this can introduce rot to the crown. Important: Only eat the stems. The leaves contain high levels of oxalic acid and are poisonous.

Flowering: Occasionally, rhubarb plants will send up a large, spectacular flower spike, usually in spring or early summer. This is known as "bolting." While the flowers can be quite architectural, they divert energy away from stem production. If you are growing for the kitchen, you should remove the flower spike immediately by cutting it off at the base as soon as you see it emerging. If you leave it, your crop of edible stems will be significantly reduced.