Herbs

Herbs split into two groups that want opposite things

Almost every herb failure comes from treating the whole category as one thing. It is not. The herbs people grow divide into two groups with genuinely opposed requirements, and knowing which one you are holding decides the watering, the soil and the pot.

The Mediterranean group wants poor soil and drought

Rosemary, thyme, sage, oregano, lavender and marjoram evolved on thin, stony, sun-baked ground. They want full sun, sharp drainage and no feeding, and they are killed by kindness faster than by neglect.

Rich soil and regular water produce soft sappy growth with weak flavor, because the aromatic oils that make these plants worth growing are concentrated by stress rather than by comfort. A well-fed rosemary tastes of very little.

The soft-leaved group wants moisture and feeding

Basil, mint, parsley, chives, coriander and dill are the opposite case. They want steady moisture, reasonable fertility and regular cutting, and they run to seed or collapse if allowed to dry out.

Most of this group is also short-lived by design. Coriander and dill bolt as days lengthen and heat rises, which is not a failure but the plant completing its cycle. The answer is successive small sowings every few weeks rather than one large one in spring.

Harvest hard, and before it flowers

Cutting is care rather than damage on almost every herb. The more frequently stems are cut, the more new growth is produced, and new growth carries the flavor.

Flowering is the point at which flavor changes, usually for the worse. Removing flower spikes as they appear keeps basil, mint and oregano productive and palatable. The exception is where the flower is the crop, as with chamomile, or where you deliberately want the pollinators, in which case a plant or two left to bloom is worth more to the garden than to the kitchen.

For drying, cut just as flower buds begin to form, when the oil content is at its highest.

Containers, and the one herb that requires them

Most herbs grow well in pots, and the Mediterranean group often grows better in them than in heavy garden soil, because a terracotta pot with gritty compost delivers exactly the drainage they want.

Mint is not a choice. It spreads by underground rhizomes and takes over a bed, and extension guidance is explicit that it should be grown in containers above ground. A pot sunk into soil is not enough, because the runners escape over the rim and root on the far side.

What overwinters and what does not

The woody Mediterranean herbs are perennial in much of the country and marginal in cold zones, where the killer is usually winter wet rather than cold. Sharp drainage does more for their survival than any covering.

Basil is frost-tender and finishes with the first cold night. Parsley is a biennial that flowers and dies in its second year. Chives and mint die back and return reliably. Each entry records which case applies, because buying a perennial herb and treating it as an annual is a small waste, and the reverse is an annual disappointment.

How to grow herbs: starting an herb garden

An herb garden is the easiest food growing there is, and it fails for one reason more than any other: it gets planted somewhere nobody walks. Herbs are picked in small amounts, in the middle of cooking, and a bed at the bottom of the garden gets visited twice in a season. Put the herbs within a few steps of the kitchen door and everything else about growing them becomes easier.

• Sun first. Most herbs want six to eight hours of direct sun, and the Mediterranean group above needs all of it. Cilantro, dill, parsley, chives and mint manage on four to six, which makes them the answer for a part-shaded spot.
• Drainage second. Herbs grow well in ordinary soil as long as water moves through it. What they do not tolerate is ground that stays wet, and no amount of feeding compensates for it.
• Resist enriching the soil for the Mediterranean group. Rich ground gives soft growth and weak flavor on rosemary, thyme, oregano and sage, and it is the most common way a well-meant herb bed disappoints.
• Give each plant its space at maturity. Rosemary and sage reach two to three feet across, and a bed planted at nursery spacing is a thicket in the second season.
• A raised bed or a large container solves a heavy clay site outright, which is why herbs are so often grown that way.

Which herbs to start from seed, and which to buy as plants

This is the decision that saves a beginner a season. Some herbs germinate in days and resent being moved; others are slow, difficult, or barely worth the wait when a plant costs a few dollars.

The pattern in that last column is worth reading on its own. The annual soft-leaved herbs are the ones to grow from seed, because they are fast and they hate being moved. The woody perennials are the ones to buy once, because a single plant lasts years and cuttings from it cost nothing.

Sowing herb seeds, which is where the fast herbs pay off

Herb seeds are small, and most of the failures come from burying them. Sow shallowly into a well drained bed or a container of ordinary potting soil, keep the surface moist until the seedlings appear, and thin without mercy afterwards.

• Sow at about twice the depth of the seed. For basil, dill and cilantro that is a quarter of an inch, barely covered.
• Keep the seedbed moist rather than wet until germination, then water less often and more deeply once the plants have several true leaves.
• Thin to the spacing on the packet. Crowded herb seedlings grow tall and thin, flop, and bolt earlier than plants given room.
• Sow the fast annuals in succession. Cilantro and dill bolt within weeks in heat, so a small sowing every two or three weeks keeps a supply going rather than delivering one flush and then nothing.
• Basil seeds want warm soil. Sown into cold ground they sit and rot, which is why basil goes in after the last frost rather than with the rest.

Growing herbs indoors, and why rosemary keeps dying

Growing herbs indoors is sold as easy and is not. The problem is light: a bright south-facing window delivers a fraction of what the same plant gets outdoors, so herbs stretch, go pale, and lose the flavor that comes from the oils they build in strong light.

• The herbs that cope: mint, chives, parsley and cilantro tolerate lower light, and mint is genuinely happy indoors.
• The herbs that struggle: basil wants heat and intense light and sulks below both. Rosemary is the one most often bought for a kitchen windowsill and the one most often dead by February, killed by dry indoor air, low light, and the extra watering that gets given in response.
• A grow light changes the answer completely. Twelve to sixteen hours a day of a basic LED turns a marginal windowsill into a workable herb garden, and it costs less than replacing the plants twice.
• Use pots at least eight to twelve inches across, with drainage holes, and let the surface dry between waterings. Indoor herbs are killed by water far more often than by neglect.
• Harvest lightly indoors. A plant growing in weak light cannot replace leaves at the rate an outdoor plant can.

Which windowsill you have decides which herbs are worth buying, and it decides it more firmly than anything else about growing herbs indoors. A south or southwest window is the only aspect that gives most herbs the four to six hours of direct sunlight they want; anything less and the choice narrows to the few that tolerate it.

The pots matter almost as much. Use containers at least eight to twelve inches across with drainage holes, filled with ordinary potting soil rather than garden soil, which compacts in a pot and holds water. Group the Mediterranean herbs together in one pot if you like, because they want the same dry treatment, and keep mint and basil separate, because they do not.

• Turn each pot a quarter every week or two, so the plant grows even rather than leaning into the glass.
• Keep the leaves off cold window glass in winter. Contact with a freezing pane damages foliage on basil faster than the room temperature ever would.
• Feed indoor herbs lightly and only in the growing season. A herb pushed with fertilizer in a dim room makes soft growth with little flavor.
• Do not repot into a much larger container. A small root ball in a large volume of wet potting soil is the fastest way to lose an indoor herb.

Preserving what you cannot use fresh

The two groups store differently for the same reason they grow differently, and getting it backwards is why home-dried basil tastes of nothing.

• Dry the Mediterranean herbs. Thyme, oregano, rosemary, sage and bay hold their oils as they dry, and the dried leaf is close to the fresh one in strength.
• Freeze the soft-leaved herbs. Basil, cilantro, parsley, chives and dill are mostly water, so drying leaves almost nothing behind. Chopped into ice cube trays with a little oil or water is the simplest method.
• Cut whole stems rather than picking individual leaves, and take no more than a third of the plant at once. Cutting back to a leaf pair is what triggers the branching that gives you the next harvest.