Question 1

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 killed.

**The process is called stratification.** A seed shed in autumn faces a lethal risk: germinate immediately and the seedling meets winter with no reserves. Species have therefore evolved a requirement for a prolonged period of **cold, moist** conditions before germination is possible. Experiencing that period is chemical proof that winter has passed and spring is arriving.

**The mechanism** involves a shift in the balance of plant hormones — a gradual decline in **abscisic acid**, which enforces dormancy, and an increase in sensitivity to **gibberellins**, which promote germination. Cold and moisture together drive this; cold alone, in a dry seed packet, achieves nothing. This is why putting dry seed in the freezer does not work.

**Which plants need it:** many trees and shrubs including apple, hawthorn, rowan and acer; herbaceous perennials such as delphinium, aquilegia, primula and lavender; and many alpines and native wildflowers. Seed packets usually say.

**How to do it.** Mix the seed with barely damp vermiculite, sand or compost, seal in a bag or container, and refrigerate at around **1–5°C**. Duration varies by species, commonly four to twelve weeks. Check occasionally for mould, and watch for seeds beginning to sprout in the fridge, at which point they should be sown immediately.

**The alternative is autumn sowing outdoors**, letting nature supply the cold naturally — often simpler and more reliable.

**Other dormancy types exist.** **Scarification** breaks or abrades a hard seed coat that water cannot penetrate — sweet peas and many legumes benefit from nicking or soaking. Some seeds need **light**, some need **smoke**, and a few require **warm** stratification followed by cold.

Question 2

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

Question 3

Why did my seeds fail to germinate?

Accepted Answer

Almost always one of five things, and the order below is roughly how often each is the culprit. Temperature. This is the most common cause and the least visible. Every species has a soil temperature

Question 4

Why does my fruit tree crop heavily one year and not the next?

Accepted Answer

It is biennial bearing — a self-reinforcing cycle in which a heavy crop in one year prevents flower bud formation for the next, producing alternating years of glut and almost nothing. The mechanism.

Question 5

What is a cold frame and do I need one?

Accepted Answer

A cold frame is a low, unheated box with a transparent lid — traditionally a wooden or brick frame with a glass "light" — that traps solar heat and shelters plants. It is the cheapest and most useful

Question 6

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

Question 7

How long do seeds stay viable?

Accepted Answer

From one year to several decades, depending overwhelmingly on the species and then on storage conditions — and the difference between species is far larger than most seed packets suggest. The

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