Your Rosemary Died Because You Treated It Like Basil

Quick answer: Basil and parsley want rich soil and steady water. Thyme and rosemary want gritty soil, full sun and to be left alone. Plant them as two separate gardens and all four will live.

The most popular herb garden in America is a thirty-inch window box with four plants in a row, watered every morning by somebody who means well. By the Fourth of July the basil is huge and the rosemary is a gray stick. Nobody did anything wrong. They just treated four plants as one.

Basil and parsley are leafy, thirsty plants that like rich ground. Thyme and rosemary come from the rocky hillsides around the Mediterranean, where summer rain is rare. Put them in the same pot with the same watering can and one pair will always be miserable. So don't.

The wet side: basil and parsley

Give these two a big container, at least 12 inches across and deeper if you can, or a corner of a raised bed. If you don't have one yet, a 4x8 bed for under two hundred dollars will hold these two and your tomatoes. Use potting mix with a couple of shovelfuls of compost worked in. Water when the top inch is dry. In a July heat wave, a pot of basil may need it daily.

Basil

Temperature matters more than the calendar. Basil sulks below 50°F, and a cold night well above freezing can blacken the leaves. Wait until nights stay above 50, which usually means a couple of weeks after your last frost date. In zone 5 that's late May or early June. In zone 9 you're planting in March. Not sure where you stand? Your hardiness zone decides what lives and what dies.

It wants six to eight hours of direct sun.

The cheapest basil you'll ever buy is the "living basil" pot in the produce aisle. It isn't one plant. It's a dozen or more seedlings jammed together. Tip it out, tease the root ball into four or five clumps, and plant them separately. Water them well and give them a few days out of harsh afternoon sun. You've just turned one grocery item into a row.

Basil also grows fast from seed. Sow it indoors four to six weeks before it's warm enough to go out, the same way you'd start seeds indoors and skip the garden center six-pack.

Pinch it. Once a plant is six to eight inches tall, cut the main stem just above a pair of leaves. Two new stems grow from that spot. Do it again on each of those and you get a bush instead of a pole. When flower spikes show up, snip them off. Once basil flowers, the leaves turn bitter and the plant starts winding down.

What goes wrong: downy mildew. The leaves yellow between the veins, and there's a gray-purple fuzz on the undersides. There's no fixing it. Pull the plant, bag it and throw it in the trash, not the compost. If you've had it before, grow resistant varieties like 'Prospera' or 'Amazel' next year.

Parsley

Grow flat-leaf, also called Italian, for cooking. It has more flavor. Curly parsley is fine, and it's prettier on a plate, but it's milder.

Parsley handles cold better than basil. It can go out two or three weeks before your last frost, and a light frost won't hurt it. It'll take part shade, about four hours of sun. That makes it the right plant for the side of the pot that gets shaded by the basil by August.

The annoying part: the seed is slow. Two to four weeks to sprout is normal, and most people give up at week two. Soak the seeds overnight in warm water before you sow. Parsley also grows a taproot and hates being moved, so either sow it where it'll stay or buy small starts and plant them without breaking up the root ball.

It's a biennial. In its second spring it shoots up a flower stalk and the leaves go tough. Pull it and replant every year.

Harvest the outer stems at the base and leave the center alone. That's where new growth comes from.

One day you'll find fat green caterpillars with black bands and yellow dots stripping your parsley to the stems. Those are black swallowtail caterpillars, and they turn into one of the best-looking butterflies in North America. Plant one extra parsley and let them have it. Your kids will watch that plant like it's television.

Southern note: in Deep South summer heat, parsley struggles. Grow it fall through spring instead.

The dry side: thyme and rosemary

These two go in unglazed terra cotta with a drainage hole. The clay pulls water out of the soil, which is exactly what you want. Fill it with potting mix cut with about a third coarse sand or perlite. Skip the compost. Rich soil and heavy feeding give you soft, floppy growth and weaker flavor. A light feeding in spring is all they need, and plenty of years they don't need that.

Water only when the top two inches are dry. Push a finger in and check. More of these plants die from kindness than from neglect. On thyme, the first sign is often yellowing lower leaves. On rosemary, needles brown from the inside out while the soil is still damp.

Give them the hottest, sunniest spot you've got. The concrete step by a south-facing wall is perfect. They like reflected heat.

Thyme

Thyme is hardy across most of the country, roughly zones 5 through 9. English thyme is the workhorse. Buy plants. The seed is tiny and slow, and one start will cover a pot by midsummer.

After it flowers, cut it back by about a third. Never cut into bare brown wood. Thyme won't regrow from there. After three or four years it gets woody and sparse in the middle. Replace it. It isn't your fault. That's just what thyme does.

Rosemary

This is where your zone decides everything. Most rosemary survives winter outdoors in zone 7 and warmer. Varieties like 'Arp' and 'Madeline Hill' are sold as hardier, and they'll sometimes make it in zone 6 with a sheltered spot. Colder than that, rosemary is either a pot you bring inside or a plant you enjoy for one season. Both are fine choices.

If you bring it in, know that the indoor winter kills more rosemary than the outdoor one. The culprits are dry furnace air, weak light and an owner who feels guilty and waters too much. Find a cool, bright spot. An unheated sunroom or a cold window in the 45 to 60°F range is ideal. Water sparingly, but don't let it go bone dry for weeks. Rosemary can die from drought without wilting first, so you won't get a warning. If white dust shows up on the needles, that's powdery mildew. Get more air moving around it.

Same rule as thyme. Never cut into old wood, and never take more than a third at once.

Put it twenty steps from the stove

An herb garden by the back fence gets visited on weekends. One by the kitchen door gets used on a Tuesday night when you're seasoning chicken and realize you could have fresh thyme in thirty seconds. Proximity is the whole game. Put the terra cotta pot on the step and the basil in the closest sunny bed.

What it costs

Prices vary by region, but a garden center herb start usually runs a few dollars to the high single digits. A seed packet is a few dollars. If you're buying a big terra cotta pot, a large plastic container, potting mix and a bag of perlite from scratch, figure roughly forty to sixty dollars to get going. If you already have a raised bed, it's a lot less.

One well-pinched basil plant in August will give you more than you can use. So will a healthy rosemary. The store clamshell is for people who haven't figured this out yet.

What to buy, what to skip

Buy

• Rosemary and thyme as plants, not seed
• Basil from seed or a split grocery-store pot
• Flat-leaf parsley, sown in place or as small starts
• Unglazed terra cotta for the dry pair

Skip

• The four-slot herb kit or window box that plants everything together
• Self-watering pots for rosemary and thyme, which keep the roots wet and rot them
• Fertilizer for the Mediterranean pair
• Saucers left full of standing water

Before the first frost

Cut all the basil the day before the first cold night. One bad night ruins it. Basil dries poorly and tastes like hay, so blend it with olive oil and freeze it in ice cube trays. Drop a cube into a pan of sauce in February and you'll feel very smart. Chop parsley and freeze it flat in a bag. Thyme and rosemary dry beautifully hung in small bunches somewhere dry and out of the sun.

Next spring, plant two gardens instead of one. The rosemary will thank you by not dying, which is about as much gratitude as rosemary ever shows.