Trees grow well from seed indoors when the seed gets the soak or refrigerator chill its species needs, is sown in a light, well drained mix kept warm, dim, and humid until it sprouts, and then moves into bright light. Seedlings often spend a few months indoors before hardening off, a gradual adjustment to outdoor conditions, and planting outside.

Why do tree seedlings need different care once they sprout?

Because the warm, dim, humid setup that helps a seed germinate does not suit a young plant, which needs bright light for sturdy stems. Seedlings left in low light tend to stretch and weaken, and constant dampness invites damping off, a fungal rot that collapses stems at the soil line.

How much light do indoor tree seedlings need?

As much as possible, starting as soon as the first sprouts appear. A bright, sunny window works, and turning the pots every few days keeps the stems from leaning toward the glass.

How should indoor tree seedlings be watered?

Moist but not wet, just as during germination. Once seedlings are up, the vented plastic cover comes off in stages to let air move. Where the surface looks dry but the pot still feels heavy, the Rapitest Mini pH Moisture Tester is inserted into the soil on its moisture setting before the next watering.

When and how are tree seedlings moved outdoors?

Gradually, over a week or two, starting with a few hours a day in a sheltered spot outside and building up until the pots stay out overnight. Planting then follows in spring or fall, in a hole at least three times the width of the pot and no deeper than the seedling that grew in it.

Frequently Asked Questions

When should a tree seedling move into a larger pot?

When roots begin to fill the container or show through the drainage holes. Moving up one pot size at a time keeps the soil from staying wet around a small root system.

What helps prevent damping off?

Good air movement, watering only as the mix starts to dry, and clean containers filled with fresh mix.

Do indoor tree seedlings need a grow light?

Not always. A bright, sunny window can be enough, while seedlings that stretch thin and pale toward the light are a sign they need more.

What helps a seedling settle in after planting outside?

Steady watering and mulch kept off the stem. TreeHelp Biostimulant, a dry powder that dissolves in water, is poured around the roots as a drench, and one 75 mL bottle treats 2 to 3 smaller or newly planted trees.