UK Vegetable Growing Guide: Crop Details, Spacing and Variety Notes
This guide covers the specific growing details that belong in your planner: sowing windows, spacings, key timings and variety notes for the most commonly grown UK vegetables. It is the crop-level reference that sits alongside the UK planting calendar — the calendar tells you when the window opens, this guide tells you what to do within it.
Quick Facts: Using a UK Vegetable Growing Guide
- RHS AGM varieties
- Assessed for consistent performance in UK trial conditions
- Soil temperature check
- Most crops need at least 7°C — use a thermometer, not the calendar date
- Spacing matters
- Tight spacing causes bolting in salads and mildew in squash and brassicas
- Record the detail
- Variety name, sow date, spacing and harvest date — the minimum useful record
For month-by-month sowing windows, see the UK Vegetable Planting Calendar →
How to use this guide
The RHS vegetable growing guides provide the evidence base for variety trials in UK conditions. The RHS Award of Garden Merit (AGM) scheme specifically tests varieties for consistent performance across different UK regions and seasons, making AGM varieties a reliable starting point for variety selection rather than relying on seed catalogue descriptions alone.
Use the crop table below as the reference that fills in the detail behind the planting calendar. When the calendar says “sow courgettes from late April to May,” this guide tells you the spacing, the minimum soil temperature and the variety choices worth recording in the planner PDF.
Crop growing details for UK vegetable gardens
| Crop | Sow window (UK) | Spacing | Notes and RHS guidance |
|---|---|---|---|
| Courgette | Late Apr – May (modules), plant out after last frost | 90cm between plants | Wide spacing prevents mildew. AGM: Defender F1, Astia (container). |
| Runner bean | Direct sow mid-May to June, after last frost | 15–20cm in rows 45cm apart | Needs support structure. AGM: Polestar, White Lady. |
| Lettuce | Mar – Sep successionally (under cover from Feb) | 20–30cm (hearting); 10cm (cut-and-come-again) | Bolts in heat — shade in July if needed. AGM: Little Gem, Saladin. |
| Carrot | Mar – Jul direct (not transplanted) | Thin to 5–7cm in rows 30cm apart | Deep, stone-free soil. AGM: Nairobi F1 (maincrop), Parmex (round for heavy soil). |
| Kale | Apr – Jun (transplant from module) | 45–60cm between plants | Crops through winter. AGM: Nero di Toscana (Cavolo Nero), Redbor F1. |
| Radish | Mar – Sep (every 2–3 weeks for succession) | 2.5cm in rows 15cm apart, thin if congested | Ready in 3–6 weeks. See how to grow radishes UK. |
| Potato | Plant tubers Mar – May (first earlies first) | 30cm apart, rows 60cm (earlies); 40cm apart, rows 75cm (maincrop) | Chit 6 weeks before planting. See when to plant potatoes UK. |
| Sweetcorn | Module Apr – May, plant out after frost in blocks | 45cm x 45cm in square blocks | Block planting aids wind pollination. See how to grow sweetcorn UK. |
Sowing in modules vs. direct sowing
The choice between module sowing and direct sowing is not always about preference — it is driven by the crop and the UK climate. Crops that dislike root disturbance (carrots, parsnips, radishes, beetroot, peas) are sown direct. Crops that need a head start (courgettes, squash, tomatoes, brassicas, sweetcorn) are started in modules and transplanted after the last frost date in your region.
For UK regions with later last frost dates — typically upland areas of Scotland, Northern England and Northern Ireland — module sowing extends the effective season by 3–6 weeks. The climate-smart growing guide explains how to read your local last frost pattern and adjust sowing dates accordingly.
Connect growing details to the wider planning system
Growing details are most useful when they feed into the planning system rather than sitting as isolated reference notes. Use the crop table above to fill in the spacing and variety columns in the planner PDF. Use the planting calendar for the sowing window. Use the crop rotation planner guide to assign each crop to the right bed family. Use the high-yield layout guide to understand block spacing and succession sowing between those crops.
Useful Next Steps
- UK Vegetable Growing Guides → — individual crop pages with step-by-step detail
- UK Vegetable Planting Calendar → — the sowing windows that go with every crop in this guide
- UK Vegetable Garden Planner PDF → — record variety, spacing, sow date and harvest result season by season
Build Your Crop-by-Crop Record
Use the UK Vegetable Garden Planner PDF to record variety names, sowing dates, spacings, harvest results and weather notes for every crop — turning this reference guide into a personalised growing record for your specific plot.
Get the Planner PDF →Ready to plan your sowing schedule? See the UK Vegetable Planting Calendar →
Frequently Asked Questions
What spacing do courgettes need in a UK vegetable garden?
Courgettes need 90cm between plants. This wider spacing prevents the powdery mildew that builds up quickly in UK summer conditions when plants are crowded. RHS AGM varieties for UK growing include Defender F1 (reliable outdoor performance) and Astia (container-friendly for smaller spaces).
When should I sow carrots in the UK?
Carrots are direct-sown (not transplanted) from March to July in the UK. They need deep, stone-free soil and should be thinned to 5–7cm apart in rows 30cm apart. Avoid recently manured soil, which causes forked roots. RHS AGM varieties include Nairobi F1 (maincrop) and Parmex (for heavy soils).
What is the difference between module sowing and direct sowing for UK vegetables?
The choice is driven by the crop. Crops that dislike root disturbance — carrots, parsnips, radishes, beetroot and peas — are sown direct. Crops that need a warm-start before the UK last frost date — courgettes, squash, tomatoes, brassicas and sweetcorn — are started in modules and transplanted after the last frost. In upland areas of Scotland, Northern England and Northern Ireland, module sowing extends the effective growing season by 3–6 weeks.
Which UK vegetable varieties have the RHS Award of Garden Merit?
The RHS Award of Garden Merit (AGM) is awarded to varieties tested for consistent performance across different UK regions and seasons. Key examples: courgette — Defender F1, Astia; runner bean — Polestar, White Lady; lettuce — Little Gem, Saladin; carrot — Nairobi F1, Parmex; kale — Nero di Toscana (Cavolo Nero), Redbor F1. The RHS AGM list is updated regularly and is the most reliable starting point for variety selection.
What soil temperature do vegetables need before sowing outdoors in the UK?
Most vegetable crops need a minimum soil temperature of 7°C before outdoor sowing. Use a soil thermometer rather than relying on the calendar date — north-facing beds and clay soils can remain cold well into April. Warmth-demanding crops such as courgettes, sweetcorn and squash need at least 10–13°C before planting out.
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