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# Starting seeds indoors

Starting seeds indoors means germinating and growing young plants in the house before they go outside. You gain weeks, you can grow varieties nobody sells as ready-grown plants, and you control the conditions.

## When to begin

Count back from your last frost date. Most seeds are started indoors about 6 to 8 weeks before it.

It varies by crop:

| Crop | Weeks before last frost |
| ---- | ---- |
| Peppers and chillies | 8 to 10 |
| Tomatoes | 6 to 8 |
| Brassicas | 4 to 6 |

Every packet states what applies to that variety. Start a little late rather than far too early: seedlings that wait indoors for weeks outgrow their pots and turn long and weak.

## What you need

- Pots or a seed tray, at least 5 to 8 centimetres deep and with drainage holes
- Fresh seed compost — light and fine, not garden soil and not old potting mix
- A mister or a can with a fine rose
- Plenty of light: the brightest windowsill you have, or a grow light
- Labels and a waterproof pen

Useful but not essential: a clear lid or propagator, a heat mat, and a small fan for airflow.

If you are reusing old pots, wash them first. That alone removes much of the risk of damping off.

## Step by step

**1. Prepare compost and pots.** Moisten the seed compost first in a bowl — damp like a wrung-out sponge, not dripping. Fill pots to about three quarters and firm lightly. Do not pack it down; it should stay open and airy.

**2. Sow.** Sow about twice as deep as the seed is wide. Large seeds such as beans can go 1 to 2 centimetres down, small seeds need only 3 to 6 millimetres of covering, and light-loving seeds stay uncovered. Sow one or two seeds per cell; if both come up, snip out the weaker one.

**3. Moisten and cover.** Mist gently so the seed is not washed out. Put a clear lid or a bag over the tray to hold the moisture in.

**4. Keep it warm.** Most seeds germinate at 21 °C or a little warmer. A heat mat holds the compost around 21 to 27 °C for heat-lovers. At this stage warmth matters more than light.

**5. Light as soon as they show.** Take the cover off the moment the first shoots appear, and move them somewhere as bright as possible. With a grow light, run 14 to 16 hours a day. Too little light gives long, weak seedlings within days. Normal room temperature of 18 °C or more is fine now, and the heat mat can come off.

**6. Water from below.** Stand the pots in a little water so the compost draws it up, then pour off the excess. That keeps the surface drier and pulls roots downward.

**7. Thin and feed.** Once the first true leaves appear — the second set, which look like the adult plant's leaves — the seed's own store is used up. Feed weekly with a heavily diluted liquid fertiliser, at a quarter to half the normal strength.

**8. Pot on.** If roots poke out of the drainage holes or the plant is clearly cramped, move it into a larger pot with fresh compost. Tomatoes and peppers often need this if you started early.

## Then: hardening off

Do not put seedlings straight outside. See *Hardening off seedlings* for the 7 to 10 day routine that gets them used to wind, sun and cool nights.

## Common mistakes

- Sowing too early, so plants outgrow their pots indoors.
- Too little light, which gives long, pale seedlings.
- Too much water, which invites damping off.
- Using garden soil or old potting mix instead of fresh seed compost.
- Forgetting to label.
- Skipping hardening off.

The full version of this guide is on [seedschoice.com](https://seedschoice.com/blogs/news/seed-starting-indoors-a-beginner-s-guide-to-jump-start-your-garden).
## Ready to sow? What you can sow now
* [Vegetables you can sow this month](https://seedschoice.com/collections/vegetables-sow-now)
* [Flowers you can sow this month](https://seedschoice.com/collections/sow-now)
* [Herbs you can sow this month](https://seedschoice.com/collections/herbs-sow-now)
* [Vegetables to sow directly outdoors](https://seedschoice.com/collections/direct-sow-vegetables)
* [Fast-growing vegetables](https://seedschoice.com/collections/fast-growing-vegetables) — quick results, ideal for beginners
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