Greenhouse and seasons
Practise first, or open the explanations as you go. A useful gardening answer includes the conditions in which it applies.
Under glass
Does an unheated greenhouse guarantee frost-free nights?
No
An unheated greenhouse gives protection but can still become cold enough for frost damage.
Why ventilate a greenhouse?
To manage heat and humidity
Appropriate ventilation helps prevent overheating and excessively humid conditions.
Can a greenhouse overheat on a sunny autumn day?
Yes
Sunshine can warm an enclosed greenhouse even when the season is cooler.
What does a minimum thermometer record?
The lowest temperature reached
Minimum readings help you understand how cold the greenhouse actually becomes.
Why keep greenhouse glazing reasonably clean?
To let more light through
Dirt and algae on glazing can reduce the light reaching plants.
Further reading: RHS guidance. Questions and explanations are original; no RHS endorsement is implied.
Winter leaves
Which description best fits winter growing?
Planning ahead for slower conditions
Many winter crops need time to establish before light and temperatures decline.
Which crop is commonly grown for leaves?
Spinach
Spinach is a leafy crop; choose a variety and sowing window appropriate to the season.
What generally happens as winter daylight reduces?
Growth slows
Shorter days and lower temperatures generally reduce growth.
Should every leaf be removed from a small salad plant at once?
No
Harvesting depends on the crop and method; leave enough healthy growth for plants you expect to regrow.
What should a winter crop plan include?
Variety and local conditions
Hardiness and suitable sowing dates depend on the variety and growing conditions.
Further reading: RHS guidance. Questions and explanations are original; no RHS endorsement is implied.
Weather and frost
What does frost-tender mean?
Easily damaged by frost
Tender plants need protection from freezing conditions.
Does a local forecast exactly equal your greenhouse temperature?
No
A greenhouse has its own conditions; measure where possible.
What is horticultural fleece used for?
Giving plants some protection
Fleece can provide protection, but its effectiveness has limits.
Why check protection after windy weather?
Covers may have shifted
Wind can move or loosen covers and supports.
Should a frost warning change the plan for tender plants?
Yes
Bring appropriate plants under suitable protection and check actual conditions.
Further reading: RHS guidance. Questions and explanations are original; no RHS endorsement is implied.
Light and seasons
Why is greenhouse space particularly valuable in spring?
It can help extend the growing season
Protection can support earlier starts for suitable crops, with temperature checks.
What can excessively close planting reduce?
Light and airflow around plants
Crowding can shade leaves and restrict air circulation.
What should guide the position of a crop?
Its light needs and the available conditions
Place crops according to their requirements rather than treating all plants alike.
Does a transparent roof mean every corner gets equal light?
No
Frames, nearby structures and other plants can create shade.
Why expect slower winter growth in an unheated greenhouse?
Lower temperatures and less light
Light and temperature strongly affect growth rates.
Further reading: RHS guidance. Questions and explanations are original; no RHS endorsement is implied.
The autumn round
Which autumn task prepares for cold nights?
Checking suitable frost protection
Prepare protection according to the crops and likely conditions.
Why avoid promising an exact first-harvest date?
Growth depends on variety and conditions
Use an expected window and verify actual readiness.
Which is a sensible autumn greenhouse priority?
Establish suitable hardy leaves while conditions allow
Choose seasonal crops and protect them appropriately.
What can an observation-only day achieve?
Spotting changes without unnecessary work
Sometimes checking conditions and leaving plants alone is the right task.
What should follow a delayed sowing?
Reassess the remaining sowing window
A delay may alter which varieties or methods remain suitable.
Further reading: RHS guidance. Questions and explanations are original; no RHS endorsement is implied.