Ipswich (IP1) — RHS hardiness H4

Frost dates and growing season for IP1

UK frost dates come from Met Office regional climate averages (1991-2020). Frost pockets, valleys, and exposed elevation can shift Ipswich-area gardens a full band colder than the regional figure. Coastal and urban gardens run a band warmer.

What grows at RHS H4 in Ipswich

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 Ipswich 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 Ipswich

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
• When to plant broccoli at RHS H4
• When to plant cauliflower at RHS H4
• When to plant cabbage at RHS H4
• When to plant kale at RHS H4
• When to plant brussels sprouts at RHS H4
• When to plant collard greens at RHS H4
• When to plant spinach at RHS H4
• When to plant swiss chard at RHS H4
• When to plant arugula at RHS H4
• When to plant beets at RHS H4
• When to plant radishes at RHS H4
• When to plant turnips at RHS H4
• When to plant parsnips at RHS H4
• When to plant kohlrabi at RHS H4
• When to plant onions at RHS H4
• When to plant leeks at RHS H4
• When to plant celery at RHS H4
• When to plant asparagus at RHS H4
• When to plant rhubarb at RHS H4
• When to plant potatoes at RHS H4
• When to plant sweet potatoes at RHS H4
• When to plant eggplant at RHS H4
• When to plant okra at RHS H4
• When to plant sweet corn at RHS H4
• When to plant pumpkins at RHS H4
• When to plant winter squash at RHS H4
• When to plant zucchini at RHS H4
• When to plant cantaloupe at RHS H4
• When to plant watermelon at RHS H4
• When to plant pole beans at RHS H4
• When to plant edamame at RHS H4
• When to plant fava beans at RHS H4
• When to plant cilantro at RHS H4
• When to plant dill at RHS H4
• When to plant parsley at RHS H4
• When to plant oregano at RHS H4
• When to plant thyme at RHS H4
• When to plant sage at RHS H4
• When to plant rosemary at RHS H4
• When to plant chives at RHS H4

For a one-shot starting point: tomatoes go outside from the late April window onwards; garlic goes in 4-6 weeks before late October; 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 IP1. Plant recommendations curated by the Growli editorial team. Last review 2026-07-03.

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

Related guides

• RHS H4 — full plant + frost guide
• Look up another postcode or ZIP
• Watering frequency calculator
• How to start a vegetable garden — beginner guide