Rosemary Care Guide: How to Grow Rosemary Indoors

Lighting Requirements

Rosemary is a full-sun plant. The number one reason it dies indoors is insufficient light. Place it directly in a south-facing or west-facing window that receives abundant direct sunlight—aim for at least 6 hours where practical. If you do not have a suitable window, supplement with a strong LED grow light. In very hot climates, some afternoon shade can help prevent leaf scorch.

Watering the Mediterranean Way

Rosemary is adapted to well-drained, relatively dry conditions and does not tolerate consistently waterlogged soil. If the soil remains soggy, root rot will set in. However, if the soil becomes entirely bone-dry, the needle-like leaves will quickly turn brown and brittle.

The Rule of Thumb: Water thoroughly when the top 2 inches of soil feel dry to the touch. Ensure the pot has drainage holes, and never let the plant sit in a saucer of standing water. Err on the side of slightly too dry rather than too wet—Rosemary is drought-tolerant but cannot recover from root rot once it has set in.

Soil and Repotting

Standard indoor potting soil holds too much moisture for Rosemary. Amend a standard mix with perlite or coarse sand, or simply use a high-quality cactus/succulent mix. Terracotta pots are highly recommended because the porous clay helps wick away excess moisture.

Fertilizer

Rosemary is not a heavy feeder. Apply a dilute, balanced liquid fertilizer once in early spring at half the recommended strength. Avoid fertilizing in winter when the plant is semi-dormant, as excess nutrients can lead to salt buildup and root burn.

Common Problems

Powdery Mildew

If you see a white, powdery coating on the leaves, improve air circulation and reduce conditions that favor prolonged leaf wetness. If treatment is needed, use a fungicide labeled for powdery mildew and follow the product directions carefully.

Crispy Brown Needles

Crispy brown leaves on Rosemary are often a sign of underwatering, but they can also indicate root rot (which prevents water uptake) or salt buildup from fertilizer. Check the soil moisture first: if it's dry, water thoroughly; if it's wet, inspect the roots for rot and repot if needed. If salt buildup is suspected (visible crust on soil), flush the soil with clean water.

Root Rot

Rosemary is prone to root problems when grown in consistently wet or poorly drained soil. Symptoms include yellowing lower leaves, wilting, and soft, mushy stems. If you suspect root rot: stop watering immediately, gently remove the plant from its pot, cut away any dark, mushy roots, and repot in fresh, dry, gritty soil.

Seasonal Care

Rosemary can thrive outdoors in summer but needs gradual acclimation to avoid sunburn. Bring it indoors before the first frost. During winter, reduce watering slightly and ensure it still receives maximum light—consider a grow light if daylight hours are short.