It’s the New Year, you may have received growing books and seeds for Christmas and now be itching to Start Growing Vegetables.

However the season is Winter in the UK and it’s cold so there’s not much chance of sowing anything outside at this time of the year.

There is hope, you can start with Indoors Seed Sowing! All you need is a large windowsill and a windowsill seed tray.

What Vegetable Seeds Can I Sow Indoors in January?

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Onion from Seed

Onions can be grown from seed or sets.

If you prefer Onion Sets, see my Free Ebook – Growing Onions from Sets. Sets can be bought in March or April.

Sow Onion Seeds in January and get ahead of the sets (young bulbs).

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Reasons To Grow Onions from Seed & not Sets

1. Start Sowing Seeds in January to get a head start on the sets planted in Late March to April.
2. Onions grown from seed are less likely to bolt (send up a flower spike) in the early summer.
3. Onions grow faster from seed and from sets.

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Onions Sowing & Planting Steps

• Difficulty Growing Level: Easy
• Sow Seeds Indoors: January to March
• Location: Indoors on a windowsill
• Equipment needed: Seed or cell tray that fits on a windowsill, compost, seeds, tray lid, little bit of water and a light, bright windowsill.
• Germination Time: 7-10 days
• Time to Transplant Outdoors: 6-8 inches tall, with 3 leaves around Mid March.
• Protection Outside: None, hardy to the cold.
• Acclimatise Onion seedlings with outdoor coldness for a few days before planting outside.
• Ground Preparation: Add lots of compost to top of soil.
• Harvest: July to September
• Video Link: Sow Onion Seeds with Me
• Update: Onions have Germinated – 5-12 Days after Sowing.

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Cauliflower

Cauliflower can be grown all year round. I’ve only ever sown Cauliflower in the late summer and harvested it in December and January due to there being little to no problem with pests at this time of the year.

This year I thought I’d mix it up a little and start sowing cauliflower in January for an early summer harvest.

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Reasons to Grow Cauliflowers

• Homemade Cauliflower Cheese! yum! and many other delicious dishes to cook with Cauliflower.
• Flavour and freshness of homegrown,
• Compact varieties available for small gardens,
• Challenge of growing a brassica plant,
• If you are a beginner to growing Cauliflower, Sow Seeds in late summer as there’s no bother with cabbage family pests when harvesting in December.

Cauliflower Sowing & Planting Steps

• Difficulty Growing Level: Intermediate.
• Sow Seeds Indoors: January to May. Sow in Jan – Feb for an earlier harvest.
• Location: Indoors on a windowsill.
• Equipment needed: Seed or cell tray that fits on a windowsill, compost, seeds, tray lid, little bit of water and a light, bright windowsill.
• Germination Time: 14-18 days.
• Time to Transplant Outdoors: 4 – 6 inches (10-15cm) tall, 6 weeks from sowing, seedlings with 4 leaves.
• Protection Outside: Yes, protect from frost with mesh netting and hoops or poles.
• Potential Pests: They will need to remain undercover during the summer due to the cabbage white butterflies that turn into caterpillars and can eat all the leaves.
• Acclimatise cauliflower seedlings with outdoor coldness for a few days before planting outside.
• Ground Preparation: Add lots of compost to top of soil.
• Harvest: June to August.
• Video Link: Seed Sow Along with Cauliflowers.

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Summer Cabbages

Summer Cabbage is another vegetable I have not grown so I’m trying to sow it in January to get a crop to turn into homemade coleslaw for the summer.

Summer Cabbages are used immediately and cannot be stored unless blanched and frozen.

You will need to choose a Summer Cabbage variety as it can handle the heat of summer whereas other varieties cannot.

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Summer Cabbage Sowing & Planting Steps

• Difficulty Growing Level: Intermediate.
• Sow Seeds Indoors: December to May.
• Location: Indoors on a windowsill.
• Equipment needed: Seed or cell tray that fits on a windowsill, compost, seeds, tray lid, little bit of water and a light, bright windowsill.
• Germination Time: 7 – 14 days.
• Time to Transplant Outdoors: 6 inches (15cm) tall, 6 weeks from sowing, seedlings with 6 leaves in April – June.
• Protection Outside: Yes, protect from frost with mesh netting and hoops or poles. 
• Potential Pests: They will need to remain undercover during the summer due to the cabbage white butterflies that turn into caterpillars and can eat the leaves.
• Acclimatise cauliflower seedlings with outdoor coldness for a few days before planting outside.
• Ground Preparation: Add lots of compost to top of soil.
• Harvest: July to September.

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Spinach

Spinach is an easy and nutritious vegetable to grow at home in your garden. It is so versatile and can be added to salads, as an accompaniment to meat, fish or with other vegetables.

I really love Spinach and I normal grow Perpetual spinach which is part of the Chard family, just because it is so easy to grow.

This year I’m going to be trying to sow different varieties of Spinach all year round, starting in January.

Spinach can even be sown outdoors in January under a cloche, yes in Winter, it loves the cold and germinates from seed in temperatures above 4 degrees.

Spinach Sowing & Planting Steps

• Difficulty Growing Level:  Easy
• Sow Seeds Indoors: January to March
• Location: Indoors on a windowsill or outdoors in the soil under a cloche as it doesn’t like frost (germinates at temps above 4 degrees)
• Equipment needed: Seed or cell tray that fits on a windowsill, compost, seeds, tray lid, little bit of water and a light, bright windowsill Or sow outdoors, directly into soil under a cloche, netting or fleece.
• Germination Time: 7 – 14 days indoors & 21 days outdoors.
• Time to Transplant Outdoors: 6-8 inches tall, with 6-7 leaves, approx 6 weeks from sowing. Let them get a bit bigger if the ground is wet outdoors (to save from slugs).
• Protection Outside: Spinach loves the cold but not like frost. Protect with a cloche, netting or fleece until all risk of frost has passed.
• Acclimatise spinach seedlings with outdoor coldness for a few days before planting outside.
• Ground Preparation: Add compost to top of soil.
• Harvest: May to October.

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Winter Lettuce

Lettuce can also be grown all year round and loose leaf varieties undercover all year round or on a windowsill, keep cutting and they will keep growing.

I never thought Lettuce could grow in Winter until I sowed a few winter lettuce seeds in late summer and forgot about them, then I had a good sized butterhead lettuce in January.

Lettuce whether it summer or winter is an easy vegetable to grow.

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Lettuce Sowing & Planting Steps

• Difficulty Growing Level:  Easy
• Sow Seeds Indoors: January to March. (Sow outdoors from March)
• Location: Indoors on a windowsill or in an unheated greenhouse.
• Equipment needed: Seed or cell tray that fits on a windowsill, compost, seeds, tray lid, little bit of water and a light, bright windowsill or Sow in trays in an unheated greenhouse.
• Germination Time: 7 – 14 days indoors & 2 – 4 weeks in an unheated greenhouse.
• Time to Transplant Outdoors: 2 – 3 inches tall, approx 3 – 4 weeks from sowing.
• Protection Outside: Lettuce does not like the cold initially. It will need fleece or cloches over the seedlings to protect from the harsh winter weather.
• Acclimatise lettuce seedlings with outdoor coldness for a 7-10 days before planting outside.
• Ground Preparation: Add compost to top of soil.
• Harvest: April to May. Ready in 10-12 weeks from sowing.

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Brand New Additions in 2025

• Seed Sowing HQ – Seeds to Sow by Month & Jobs To Do.
• Beginners Hub – Start Growing Veg this year with our Brand New – Beginners Hub, helping you every step of the way on how to sow seeds, plan what you want to grow, how to prepare your outdoors site and more.
• Events – Seed Sow Along Video Release Schedule for 2025.
• How to Create a Simple Seed Sowing Setup Indoors.

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Written by Tracey Everett – SowGrowHarvest.co.uk

Instagram – @traceysowgrowharvest

Threads – @traceysowgrowharvest

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