Why are my seeds not germinating?

Check the packet's expected germination time, temperature and light requirements. The mix should remain evenly moist, not waterlogged or bone-dry. Old seeds, seeds buried too deeply and temperatures outside the recommended range can delay or prevent germination. Wait for the specified window before starting over.

When should I remove a humidity dome?

Remove or open the cover once seedlings start emerging so air circulates and leaves stay dry. A closed dome left on after sprouting can increase mould and damping-off risk. Check moisture without letting the mix dry completely.

What can I do about tall, weak or leaning seedlings?

Move seedlings into brighter appropriate light and follow any grow-light height and duration guidance. Turn trays if light comes from one direction and ensure gentle airflow. Avoid excessive heat and overwatering. Very stretched seedlings may not recover fully.

How do I know seedlings are ready to move outdoors?

Check the crop's recommended transplant stage and nighttime temperature needs. Seedlings generally need some true leaves and a healthy root system, but the packet's directions come first. Gradually harden off before planting; protect frost-tender varieties from cold and strong wind.

Guides/Garden/How to Start Seeds Indoors in Seed Trays

How to Start Seeds Indoors in Seed Trays

Start vegetable, herb or flower seeds in small indoor trays before the outdoor growing season. Follow the seed packet for sowing depth and timing, keep the mix evenly moist, give emerging seedlings enough light and acclimate them gradually before transplanting. Not every plant benefits from indoor starting.

Updated Nov 14, 2026

35 min7 stepsBeginnernew

What you need

Tick off what you already have.

Tools

Clean seed tray or small pots with drainage holes
Watering can with a fine rose or spray bottle
Plant labels and pencil
Small scoop or spoon

Materials

Seeds suitable for indoor starting
Fresh seed-starting compost or sterile seed-starting mix
Clean water
Optional clear propagation lid

Seed packets, a calendar and clean seed-starting supplies arranged on a table.

AI illustration

Step 01 / 07

Check the seed packet and choose a start date

Read the packet for whether this crop benefits from indoor sowing, how many weeks before the local last frost to start, its germination temperature and its sowing depth. Count backward from the expected transplant date. Do not start varieties that dislike root disturbance indoors unless the packet recommends it. Set out only the seeds and containers you need.

Guide progress1 / 7

1. Check the seed packet and choose a start date
Instructional illustration generated with AI for Howmigo.
Read the packet for whether this crop benefits from indoor sowing, how many weeks before the local last frost to start, its germination temperature and its sowing depth. Count backward from the expected transplant date. Do not start varieties that dislike root disturbance indoors unless the packet recommends it. Set out only the seeds and containers you need.
2. Prepare clean containers with drainage
Instructional illustration generated with AI for Howmigo.
Use washed seed cells or small pots with open drainage holes; do not sow into a sealed container. Put the tray on a waterproof catch tray. Label each row or pot with the plant name and sowing date before handling small seeds. Keep old plant debris and used compost away from the new sowing area.
3. Moisten and fill the seed-starting mix
Instructional illustration generated with AI for Howmigo.
Use a fresh, fine seed-starting mix, not heavy garden soil. Add a little clean water and stir until it feels like a wrung-out sponge, with no water dripping when gently squeezed. Loosely fill the cells to just below the rim and level the surface; avoid compacting the mix so roots and air can move through it.
4. Sow each seed at its recommended depth
Instructional illustration generated with AI for Howmigo.
Place the recommended number of seeds in each cell, following the packet's spacing and depth. Some very small seeds need light and should be pressed on the surface rather than buried. Cover other seeds with the specified thin layer of mix and press gently for contact. Do not substitute a universal depth or bury light-germinating seeds.
5. Water gently and keep conditions suitable for germination
Instructional illustration generated with AI for Howmigo.
Mist the surface or water carefully from below until evenly moist, then drain excess water. If the packet recommends it, set a loose clear lid over the tray to retain humidity; leave ventilation and remove the lid once seedlings emerge. Keep the tray at the crop's recommended temperature, away from radiators, harsh direct heat and standing water. Check moisture daily.
6. Give seedlings light and thin without pulling roots
Instructional illustration generated with AI for Howmigo.
As soon as shoots appear, move them to bright suitable light or use a purpose-made indoor grow light according to its instructions. Follow the crop's needs and avoid overheating leaves. Keep the mix lightly moist, never waterlogged; allow the surface to dry a little when appropriate. If several seedlings emerge in one cell, snip the weaker ones at soil level rather than tugging roots out. Watch for collapsed stems, mould or persistent sogginess and correct moisture and airflow.
7. Harden off and transplant only when ready
Instructional illustration generated with AI for Howmigo.
Check the packet for transplant size, spacing and safe outdoor temperatures. After frost danger has passed for tender crops, gradually introduce seedlings to sheltered outdoor conditions over about 7–10 days, starting with a short period out of strong sun and wind and increasing exposure as tolerated. Bring them inside during cold snaps. Water before transplanting, handle by the leaves rather than the fragile stem, plant at the crop-appropriate depth and water in gently. Delay planting if conditions are unsuitable.