Question 1

What is dormancy, and why do plants die back?

Accepted Answer

Dormancy is an **active, regulated shutdown** rather than a passive response to cold — plants prepare for it in advance, and understanding that explains a great deal of seasonal gardening advice.

**How a plant knows winter is coming.** Not from temperature, which is unreliable, but from **shortening day length**, measured by the same pigment system that controls flowering. Declining daylight triggers preparation weeks before the first frost.

**What preparation involves:** withdrawing nutrients from leaves back into stems and roots — which is why autumn leaves change colour as chlorophyll is dismantled and underlying pigments become visible; forming an **abscission layer** at the leaf base to shed leaves cleanly and seal the wound; accumulating sugars and protective proteins that act as antifreeze; reducing cell water content; and setting buds for next spring, which are formed **before** winter, not during it.

**Why herbaceous perennials die back completely.** Maintaining top growth through winter costs energy and risks frost damage, so the plant abandons it and retreats to roots, rhizomes or tubers where stored reserves are protected underground. **The plant is not dead and should not be dug up**, which is a common and expensive mistake.

**Why dormancy must be broken properly.** Many plants require a period of cold — **vernalisation** for flowering, **stratification** for seeds — before they will grow. This prevents a warm spell in autumn triggering growth that winter would kill. It is why some seeds need chilling before sowing, why fruit trees have **chill hour** requirements, and why warming winters are a genuine problem for some crops in some regions.

**What follows practically:**

**Do not feed or prune late in the season** in a way that stimulates soft growth, which will not harden before frost.

**Leave dead top growth on many perennials** over winter — it protects the crown and shelters insects.

**Plant bare-root stock while dormant**, which is why it is sold in winter and establishes better than container-grown.

**A mild winter followed by a cold snap** is far more damaging than a steadily cold one, because plants may have already begun to break dormancy.

Question 2

What is the difference between annual, biennial and perennial plants?

Accepted Answer

The words describe how long a plant takes to complete its life cycle, which in practice tells you how often you will be replanting. An annual germinates, grows, flowers, sets seed and dies within a

Question 3

Why do some seeds need a cold period before they germinate?

Accepted Answer

Because they have a built-in dormancy mechanism that prevents germination until the seed has experienced winter — an adaptation that stops seedlings emerging at the wrong time of year and being

Question 4

Why do leaves change colour in autumn?

Accepted Answer

Because the tree withdraws its most valuable resources before discarding the leaves — and the colours reveal what was there all along, plus something newly made. The green is chlorophyll, the pigment

Question 5

Why do plants flower when they do?

Accepted Answer

Mostly because of day length, which is the only environmental signal reliable enough to time a life cycle by — temperature varies wildly from year to year, but the length of the night on a given date

Question 6

Why does a plant look worse at home than it did in the garden centre?

Accepted Answer

Because it was grown in conditions you cannot reproduce, and what you bought was a plant at an artificial peak rather than a plant in a stable state. What commercial growing does to a plant: Ideal

Question 7

What happens to a plant when it freezes?

Accepted Answer

The damage is done by ice forming in the wrong place, and the difference between a plant that survives a hard frost and one that turns to mush is mostly about where the ice forms rather than how cold

Related Questions