How to care for your indoor lavender

Once lavender is potted and settled, the work is mostly restraint. It is fed less than most houseplants, watered less often, and pruned harder. This covers the ongoing care. For choosing a variety and getting the plant into a pot in the first place, see growing lavender indoors.

Light

Lavender needs six to eight hours of direct sun a day, and light is the first thing to check when an indoor plant looks wrong.^[1]

A south-facing window is the only orientation that supplies it reliably, and even that falls short between November and February in most of the US. Rotate the pot a quarter turn every few days so the plant grows evenly instead of leaning into the glass.

Underlit lavender is easy to identify. The stems stretch, leaving long bare gaps between leaf pairs, the foliage pales from grey-green toward yellow-green, and the plant does not flower. None of that reverses on the existing growth. You fix the light and the new growth comes in normal.

A full-spectrum LED covers the winter shortfall. The GE BR30 Full Spectrum LED Grow Light screws into a standard socket and runs cool enough to sit close to the plant. Position it 12 to 24 inches above the foliage and run it 12 to 14 hours a day.

Watering

Water thoroughly, then wait until the top two inches of soil are dry before doing it again. That is roughly weekly in summer and every two to three weeks in winter, and the interval matters far less than the finger test.

Water the soil rather than the foliage, and empty the saucer once the pot has drained. A pot standing in water will rot within weeks.

Overwatered and underwatered lavender look different, and telling them apart saves plants:

• Overwatered: yellowing leaves starting at the base, a soft or darkened stem at soil level, wilting despite damp soil, and a sour smell from the pot. This is root rot and it is often fatal by the time it shows.
• Underwatered: grey-green leaves going dull and brittle, stems drooping, soil pulled away from the sides of the pot. Water it and it recovers within a few hours.

Wilting on wet soil means stop watering. Wilting on dry soil means water. The symptom is the same and the treatments are opposite, which is how most indoor lavender is lost.

Humidity and air movement

Lavender wants 30–50% relative humidity, and this is the requirement people overlook.

Damp, still air brings grey mold on the lower foliage and makes root rot more likely at any given watering frequency. Kitchens and bathrooms are the worst places in the house for it.

Air movement solves more of this than a machine. Leave a hand’s width of space around the pot rather than crowding it between other plants, and run a small fan in the room for a few hours a day if the air is still. If your home runs genuinely humid, a compact dehumidifier will hold a small room in range.

A pebble tray is the wrong move here. Those raise local humidity, which is the opposite of what lavender wants.

Pruning

Pruning is what keeps lavender from turning into a bare woody stump with a tuft on top, and indoor plants need it more than outdoor ones because low light makes them leggy faster.

Prune twice a year. In early spring, before new growth starts, take off up to a third of the plant and shape it into a rounded mound.^[2] After flowering, cut the spent flower stalks back into the foliage to tidy it and encourage a second flush.

The rule that matters: never cut into the old, grey, leafless wood at the base. Lavender does not reliably regrow from bare wood, and a hard cut into it kills that stem for good. Always leave green growth below your cut.

Harvesting

Cut when the buds have colored up but before the flowers fully open, which is when the scent is strongest. Morning, after the dew has dried, is the traditional timing and it holds up.

Cut whole stems down into the green growth, take no more than a third of the plant at once, and leave the woody base alone. How to use lavender covers drying and what to do with the buds afterward.

Feeding

Lavender evolved on poor soil and a well-fed plant is a worse plant. Overfeeding produces soft, sappy growth that flops, attracts aphids, and carries noticeably less scent, because the oils that make lavender smell like lavender are concentrated by mild stress.

Feed lightly once in spring and leave it at that. A slow-release organic granular such as Espoma Organic Plant-tone works well, applied at half the rate on the box. Skip feeding entirely in autumn and winter.

Refreshing the top inch of potting mix each spring does more good than fertilizer for a plant this frugal.

Soil and repotting

Lavender wants sharp drainage and a slightly alkaline soil, around pH 7.0 to 7.5. Most potting composts are formulated acidic, and a plant sitting in acidic mix slowly weakens for no visible reason. A tablespoon of garden lime worked into the pot brings it into range for a season or two. Our guide to testing soil pH covers how to check.

Repot every two or three years, in spring, into a pot one size larger. Potting mix compacts over time and drainage worsens exactly as the plant gets bigger. Signs it is due: roots at the drainage hole, water sitting on the surface instead of soaking in, and growth that has stalled despite good light.

Go up one size only. A pot much larger than the root ball holds wet soil the roots cannot reach.

Temperature

60–80°F suits it through the growing season. Below 50°F growth stops, which is normal and not a problem in itself.

Keep it clear of radiators, heating vents and cold glass on frosty nights. Steady conditions matter more than any particular number, and a plant that swings between a hot vent and a cold window is under more stress than one kept a few degrees off ideal.

A cool winter rest, somewhere around 50–60°F, gives you better flowering the following year. A bright unheated room works well for this.

Dwarf and full-size varieties

Dwarf English cultivars like ‘Munstead’ and ‘Hidcote’ have smaller root systems and dry out faster in small pots, so check them more often in summer. Their light requirement is identical to the full-size types.

Full-size lavender kept indoors needs a larger pot and more frequent repotting, and it will still outgrow the situation eventually. If you inherited one, treat it as a plant on borrowed time and take cuttings while it is healthy.

Routine checks

Once a week, put a finger in the soil and look at the base of the plant. That covers most of what goes wrong. Check the undersides of the leaves for aphids and spider mites every couple of weeks, more often in a heated room in winter, and look for grey mold on the lowest foliage if the air is damp.

Yellowing at the base is a watering problem. Stretched growth is a light problem. Grey fuzz is an airflow problem. Each has a section above.

For more on the propagation, varieties and setup side, see growing lavender indoors.

References

1. University of Maryland Extension, “Lavender.” https://extension.umd.edu/resource/lavender ↩︎

2. Michigan State University Extension, “Lavender: a beautiful and useful herb.” https://www.canr.msu.edu/news/lavender_a_beautiful_and_useful_herb ↩︎