UK hardiness lookup
London (south-east) (SE) — RHS hardiness H4
London (south-east), England · 198-day frost-free season
Frost dates and growing season for SE
| RHS hardiness rating | H4 |
|---|---|
| Average last spring frost | mid-April |
| Average first autumn frost | early November |
| Growing season length | ~198 days |
| Temperature range (C) | minimum -10 to -5 °C |
| Temperature range (F) | minimum 14-23 °F |
| USDA equivalent | Roughly USDA zone 8a/8b. |
UK frost dates come from Met Office regional climate averages (1991-2020). Frost pockets, valleys, and exposed elevation can shift London (south-east)-area gardens a full band colder than the regional figure. Coastal and urban gardens run a band warmer.
What grows at RHS H4 in London (south-east)
The default rating for "British garden hardy". Plants in this band cope with most UK winters but can be damaged in unusually cold years.The RHS rates plants — not regions — so check the rating on each plant's tag against this H4 baseline. Anything rated H4 or hardier (numerically higher) should overwinter reliably in a typical London (south-east) year.
- Buddleja davidii
- Lavandula angustifolia
- Rosa (most modern shrub and floribunda roses)
- Sarcococca (sweet box)
- Camellia japonica
- Choisya ternata
- Ceanothus (most cultivars)
- Hydrangea macrophylla
- Wisteria
- Magnolia (M. grandiflora, M. soulangeana)
When to plant in London (south-east)
Sowing, transplant, and harvest dates for the most common edible crops, calibrated to RHS H4 timing:
- When to plant tomatoes at RHS H4
- When to plant peppers at RHS H4
- When to plant basil at RHS H4
- When to plant garlic at RHS H4
- When to plant lettuce at RHS H4
- When to plant bush beans at RHS H4
- When to plant cucumbers at RHS H4
- When to plant summer squash at RHS H4
- When to plant peas at RHS H4
- When to plant carrots at RHS H4
For a one-shot starting point: tomatoes go outside from the mid-April window onwards; garlic goes in 4-6 weeks before early November; brassicas and salads can run on either side of the frost window with fleece in cold snaps.
Local microclimate notes
Postcode-area ratings are a baseline — your actual garden can sit a band warmer or colder. Urban heat-island effect lifts inner-city gardens; frost pockets at the bottom of slopes drop them. If you can record your own lowest winter temperature for a couple of seasons, that beats any regional average for planning.
For US gardeners reading UK references: RHS H4 is Roughly USDA zone 8a/8b. — see the matching USDA Zone 8 guide for the US-side planting calendar.
Source and methodology
Hardiness rating from the Royal Horticultural Society hardiness rating scale. Frost-date averages from Met Office UK climate averages (1991-2020), matched to the nearest representative regional station for postcode SE. Plant recommendations curated by the Growli editorial team. Last review 2026-05-19.
Other postcode areas in England
- EC1 — London (Clerkenwell) (RHS H4)
- EC2 — London (City) (RHS H4)
- WC1 — London (Bloomsbury) (RHS H4)
- WC2 — London (Covent Garden) (RHS H4)
- W1 — London (Mayfair / Soho) (RHS H4)
- SW1 — London (Westminster / Belgravia) (RHS H4)
- NW1 — London (Camden) (RHS H4)
- N1 — London (Islington) (RHS H4)
- E1 — London (Whitechapel) (RHS H4)
- SE1 — London (Southwark) (RHS H4)
- SE10 — London (Greenwich) (RHS H4)
- SW19 — London (Wimbledon) (RHS H4)
- Browse all UK postcode areas