Indoor Herb Garden: How to Grow Fresh Herbs All Winter

An indoor herb garden works when you give herbs what a windowsill rarely provides in winter: enough light. Most herbs need about 6-8 hours of direct sun a day, which means a bright south-facing window or a grow light running 12-16 hours, set 6-12 inches above the leaves. Add a fast-draining potting mix, pots with drainage holes and careful watering, and parsley, chives, mint, thyme and oregano will keep you in fresh leaves all winter.

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How much light do indoor herbs need?

Light is the number one reason indoor herbs fail. Iowa State Extension notes that most herbs need about eight hours of direct light indoors, and Penn State Extension puts the minimum around six hours. In winter, even a south-facing window gives weaker, shorter light than summer sun, especially in northern states.

South window vs. grow light

• South-facing window: the best natural option. Set pots right against the glass, rotate them weekly and keep leaves from touching cold panes.
• East or west window: workable for chives, parsley, mint and cilantro, which tolerate less light. Expect slower growth.
• North window: not enough for most herbs without a grow light.
• Grow light: a full-spectrum LED fixture 6-12 inches above the leaves, on a timer for 12-16 hours a day, grows compact, flavorful herbs anywhere in the house, including a kitchen counter or basement shelf. The same fixtures sold as grow lights for seedlings work well.

Leggy, pale stems that lean toward the window are the sign of too little light. The same principles that stop leggy seedlings apply to herbs: more light, closer.

Best herbs to grow indoors

Basil: possible, with caveats

Basil is the herb most people want indoors and the one most likely to sulk. It needs warmth and strong light, and cold drafts damage it quickly; Penn State Extension warns that basil does not survive below 50°F, so a winter windowsill next to cold glass is risky. Grow it under a grow light in a warm room, pinch the tips often and expect smaller harvests than in summer. Starting fresh plants from seed or rooting tip cuttings in late summer usually works better than digging up a big, woody garden plant.

Parsley, chives and mint: the reliable trio

These three tolerate lower light and cool rooms. Parsley grows a long taproot, so give it a pot at least 8 inches deep. Chives can be divided from a garden clump in fall and potted up. Mint spreads aggressively, so keep it in its own container.

Thyme and oregano

These Mediterranean herbs want bright light and a mix that dries out between waterings. Terracotta pots help because they breathe and dry faster than plastic.

Rosemary: overwintering indoors

Rosemary is generally hardy only to about zone 7, so in colder zones most gardeners bring it in for winter. It’s the hardest common herb to keep alive indoors: University of Illinois Extension notes that it prefers a cool spot around 50-60°F with very bright light, while most homes are too warm and dry. A cool, sunny room or an unheated sunporch that stays above freezing works best. Water when the top inch is dry; a rosemary whose root ball dries out completely often won’t recover. If you have no good spot, take cuttings in late summer and root them as a backup.

Bringing herbs indoors: timing by zone

Move tender herbs inside before your first fall frost; basil should come in sooner, once nights drop toward 50°F. Use the table as a rough guide and check your local frost dates, since microclimates vary and your extension office can give you exact local averages.

In zones 8-10, cool-season herbs like parsley, cilantro and dill grow better outdoors in fall and winter than in summer, so an indoor garden there is mostly for basil during cold snaps or for convenience.

How to bring garden herbs inside

1. Pot up plants a week or two before frost, using fresh potting mix in a container with drainage holes.
2. Leave the pots in a shady spot outdoors for a few days to adjust.
3. Inspect the tops and undersides of the leaves for aphids, spider mites and whiteflies; rinse the foliage with a strong spray of water.
4. Move the plants to their sunniest indoor spot or under a grow light, and keep them away from other houseplants for a week or two.
5. Trim back about one-third of the growth to reduce stress.

Containers, soil and watering

Use a good-quality potting mix, never garden soil, which compacts in pots and can carry pests. Every pot needs a drainage hole; a decorative cachepot is fine as long as you empty it after watering. A 6-8 inch pot suits most single herbs, and parsley wants a deeper one.

Water when the top of the mix feels dry for most herbs; basil, mint, chives and parsley like it a bit more evenly moist, while thyme, oregano and sage like to dry out more. Overwatering is the most common killer indoors. Feed lightly: a balanced water-soluble fertilizer at half or quarter strength every few weeks while plants are actively growing. Too much fertilizer produces lush leaves with less flavor. Most herbs are comfortable at 65-70°F during the day and 55-60°F at night.

Countertop hydroponic herb gardens

Countertop hydroponic units grow herbs in water with built-in LED lights and a pump, and they solve the light problem neatly. Before buying, compare a few points: how high the light can rise (basil gets tall), whether you can use your own seeds or must buy the brand’s seed pods, the ongoing cost of pods and nutrients, and how easy the reservoir is to clean. Change the water and clean the unit regularly to prevent algae and odors. A grow light over regular pots does the same job with more flexibility; the hydroponic unit wins on convenience.

Pests on indoor herbs

Indoor herbs have fewer pests than outdoor ones, but a few show up often:

• Fungus gnats: tiny dark flies around damp soil. Let the surface dry between waterings and use yellow sticky traps.
• Spider mites: fine stippling and webbing, worse in dry, heated air. Rinse leaves often, especially rosemary and thyme.
• Aphids: clusters on new growth. Wash them off with a strong spray of water or pinch off the infested tips.
• Whiteflies: tiny white insects that fly up when disturbed. Yellow sticky traps help you spot and reduce them.

Since you eat the leaves, stick with water sprays, pruning and sticky traps first. If you use insecticidal soap or another product, choose one labeled for edible herbs and follow the label.

How to harvest indoor herbs

Harvest often to keep plants bushy. Snip leafy annuals such as basil and cilantro just above a pair of leaves; pinching basil tips encourages branching. For perennials like thyme, oregano, mint and rosemary, never remove more than one-third of the plant at once. Cut chives and parsley from the outside, leaving the center to keep growing. When annual herbs get woody or stop producing, compost them and start fresh. For an even faster indoor harvest, try growing microgreens alongside your herbs.

Common mistakes to avoid

• Relying on a north or shaded window in winter.
• Using garden soil or pots without drainage holes.
• Watering on a schedule instead of checking the soil.
• Letting basil sit against cold glass or in a drafty spot.
• Keeping rosemary in a warm, dry room or letting its root ball dry out.
• Bringing herbs indoors without checking for pests.
• Cutting perennial herbs back by more than one-third at once.

FAQ

Keep reading

• How to Cover Plants for Frost: What Works and What Doesn't
• Cold Frame Gardening: How to Build One and What to Grow
• Winter Vegetables: 16 Cold-Hardy Crops and How Cold They Go

Sources

• Growing Herbs Indoors – Iowa State University Extension
• Growing Herbs Indoors – Penn State Extension
• Rosemary – University of Illinois Extension
• Managing Insects on Indoor Plants – University of Minnesota Extension
• Growing Herbs at Home – University of Missouri Extension
• USDA Plant Hardiness Zone Map – USDA Agricultural Research Service