Plants that respond well to the Hampton hack include:

Acanthus
Alchemilla
Brunnera
Centranthus
Delphinium
Early-flowering geraniums (Geranium sylvaticum, Geranium endressii and Geranium phaeum)
Knautia
Lemon balm (to encourage fresh foliage for cooking)
Lupins
Mint (to encourage fresh foliage for cooking)
​Monarda 
Oriental poppies
Polemonium
Pulmonaria
Early-flowering salvias, including x sylvestris cultivars such as 'Mainacht' and 'Blauhügel'
Veronica

Many other early-flowering

Perennials are any plant living for at least three years. The term is also commonly used for herbaceous perennials which grow for many years (To compare: annual = one year, biennial = two years).

The cut-back is performed after flowering, usually in late June or early July, i.e. around the time of the RHS Hampton Court Palace Garden Festival. The technique works less well during drought conditions, so in very dry periods consider delaying until after rainfall to help the plants put on new growth.

Traditionally many early-flowering perennials have been cut back after they have bloomed, and the name Hampton hack has been coined for this technique in recent years.

All these plants can regrow from shoots at the base, so cutting to ground level encourages new stems to form (the shoots at the top would normally inhibit the shoots at the base by producing hormones in a process called apical dominance).

To carry out the Hampton hack:

1. Clumps of perennials can be cut back to nearly ground level, just above the base of the plant, using shears or secateurs. This will remove tired foliage and faded flowers and promote new growth
2. Compost the foliage and if the ground is dry, consider watering to promote regrowth

There are few problems associated with this technique. However, drought will impede regrowth and inhibit re-flowering.