Alan's perennial size guide

As they're quicker for nurseries to grow to a substantial size, there's a smaller difference in price between small perennial plants and larger specimens. Keep an eye out for specialist mail order nurseries who send out a wide range of cheaper, smaller plants, including choice and more common varieties.

Discover the perennial sizes available, along with their benefits and drawbacks, in Alan Titchmarsh's perennial size guide.

Small square pots (7-9cm)

Young plants with small rootballs, widely available from garden centres in spring and usually the size sent out from mail order nurseries.

• Pro: cheap and more reliable than bare-root perennials
• Pro: wide range available by mail order from specialist nurseries
• Pro: ideal for planting large drifts in borders or as groundcover
• Con: still best to pot up and grow on before planting out

These plants are usually one year old and cost approximately £2-£4.50.

Standard pots (1-2 litre)

The standard garden centre sales size. Sold all year.

• Pro: good value for money
• Pro: garden-ready and easy to establish outside
• Con: smaller garden centres offer limited choice of varieties at this size
• Con: often sell out quickly when in flower and are then not available again until the following year

Plants in standard pots are usually two to three years old, and cost £4-£9.

Large pots (3-5 litre)

Often sold seasonally at garden centres when the plants are looking their best.

• Pro: instant impact
• Pro: perfect for making focal points and features in a border or large container
• Con: very limited range available
• Con: need careful soil prep and aftercare to get established
• Con: high price

These plants are usually three to four years old and cost approximately £8-£20.

Looking to buy shrubs or trees for the garden? Take a look at Alan's shrub size guide and tree size guide, so you know what to expect for the price you pay.