AUTUMN / THE FIRST SOWING
September in an
unheated greenhouse.
Start small. Give suitable hardy leaves a chance while there is still warmth and light.
Three priorities
- Prepare and label a modest sowing area.
- Sow suitable winter salads and hardy spinach within their variety windows.
- Use an established parsley plant for a simple herb corner if available.
Before you start
Check the compost before reaching for the watering can. Unheated glasshouses can still get cold.
Check which crops are actually present, their stage of growth and the instructions for their varieties. Move a job if its conditions are not met. A blank harvest record is more useful than an invented success.
Our first-season task sequence · 2026
Suggested dates, not completion records. Use the next suitable opportunity if a job is delayed.
- 9 September: Choose and label the first small growing area.
10 min; photograph its actual starting state if James wants a journal record. - 10 September: Check the winter-salad and spinach varieties and their September sowing instructions.
10 min; confirm supplies before promising a sowing. - 11 September: Prepare a small area or clean modules for the first sowing.
15 min; Friday review records what is actually ready. - 12 September: Sow a modest first batch of suitable winter salad leaves.
15 min; only if seed, medium and conditions are suitable. Otherwise finish preparation. - 13 September: Plan the week's three small jobs and label any sowing already made.
10 min; Sunday review. - 14 September: Sow a small batch of suitable hardy spinach if its packet permits this window.
15 min; do not sow merely because the calendar says so. - 15 September: Inspect the ventilation arrangements on a mild day.
5 min; manage overheating without assuming fixed vent settings suit all weather. - 16 September: Check the surface of any sown trays for moisture and disturbance.
5 min; no automatic watering. - 17 September: Place or pot an available healthy parsley plant.
10 min; if none is available, mark its planned position. - 18 September: Record the first week's actual changes.
10 min; Friday review, including “no visible change” if that is true. - 19 September: Inspect young growth and growing areas for slug or snail damage.
5 min; identify the cause before choosing treatment. - 20 September: Choose next week's priorities from what is growing and what is still missing.
10 min; Sunday plan. - 21 September: Compare germination with the seed packet's expected window.
5 min; do not label a sowing failed prematurely. - 22 September: Thin crowded seedlings only if they are ready.
Up to 10 min; follow variety spacing guidance. Otherwise observe. - 23 September: Check the overnight minimum reading if a thermometer is available.
5 min; do not invent a temperature if no reading exists. - 24 September: Review whether a small second salad sowing is still suitable.
10 min; variety, light and conditions govern the decision. - 25 September: Photograph or note the week's genuine progress and one concern.
10 min; Friday review. - 26 September: Check an established parsley plant and remove damaged foliage if present.
5 min; inspect rather than assume a problem. - 27 September: Plan the handover into October.
10 min; Sunday plan, keeping time estimates realistic. - 28 September: Remove plant debris and tidy the accessible growing area.
10 min; avoid disturbing new seedlings. - 29 September: Check whether salad seedlings are sturdy enough for their next stage.
5 min; move them only when ready, not to meet a date. - 30 September: Write a short September record of actual sowings and observations.
10 min; distinguish plans, completed work and unknowns.
A useful five-minute inspection
Look at moisture, temperature and new growth. If foliage looks damaged, inspect both sides and take a clear photograph before deciding on a treatment. Water the growing medium only when needed.
Read, learn, then try
RHS greenhouse growing · RHS winter growing · Our crop notes