Peppers Want Warm Feet, So Plant Them Later Than You Think

Quick answer: Don't plant peppers until the soil is 60°F or warmer and nights stay above 55°F. If your summer is short, grow hot peppers and small sweet ones, not big bells.

Your peppers sat there all of June looking exactly like the day you bought them because you planted them on Mother's Day into 52-degree dirt. They didn't die. They just stopped. A pepper that gets cold feet in its first two weeks can sulk for a month, and the neighbor who planted his on June 5th will be picking jalapeños while yours are still deciding whether to grow.

That's the whole secret. Everything else is detail.

Buy a soil thermometer before you buy a plant

A basic probe thermometer runs about ten dollars at any garden center. Push it four inches into the bed at eight in the morning, when the soil is coldest. When it reads 60°F three mornings in a row, you're clear. Most of the country gets there two to four weeks after the last frost date, not on it.

Tomatoes will tolerate a cool start. Peppers won't. They're tropical plants that we grow as annuals, and they act like it.

Your zone tells you roughly when this happens. In Zone 8 or 9, you might plant in April and get a second flush of fruit in fall once the heat breaks. In Zone 5, you've got maybe 100 to 120 frost-free days, and a pepper that needs 90 of them after transplant leaves you no room for a slow start. If you aren't sure where you stand, read Your Hardiness Zone Decides What Lives and What Dies before you pick varieties.

Hot peppers are easy. Bell peppers are the hard ones.

This surprises people. The fat, blocky bell pepper in the grocery store is the fussiest pepper you can grow. It needs a long, steady, warm season to size up, and then it needs another few weeks on the plant to turn red. In a short summer, you'll get a handful of small green ones and a lot of frustration.

Hot peppers set fruit faster, put up with more neglect and produce like crazy. A single healthy jalapeño plant can bury a family of four by August.

So choose by your season, not your shopping list:

• Short season (Zones 3 to 5): Jalapeño, Hungarian Wax, Shishito, and early sweet peppers like Ace or King of the North for bells. Carmen, a sweet Italian horn pepper, ripens red faster than any bell.
• Middle (Zones 6 and 7): Almost anything. Serrano, Cayenne and Jimmy Nardello, an heirloom frying pepper that tastes like candy once it's blistered in a pan. Try one bell if you want, but don't build the garden around it.
• Long and hot (Zones 8 and up): Habanero and the other slow, fiery ones that need 90-plus days after transplant. Bells do better here too, as long as you plan around midsummer heat.

The seed packet lists "days to maturity." With peppers, that count starts at transplant, not at seed, and it means green fruit. Add two to three weeks if you want them red, orange or yellow. A green bell is just an unripe red one. That's why red bells cost more at the store.

Starting from seed, or not

Garden center transplants usually run four to six dollars each. A packet of seed costs three to five dollars and holds twenty or more. If you want anything beyond the standard jalapeño and green bell, seed is the only way to get it.

Peppers are slow. Start them eight to ten weeks before your last frost, on a heat mat. They germinate best around 80°F, and on a cool windowsill they can take three weeks to come up, if they come up at all. A seedling heat mat costs around twenty dollars and lasts for years. Superhot varieties like habanero are the slowest, so start those first. Start Seeds Indoors and Skip the Garden Center Six-Pack covers lights and timing in detail.

If you buy transplants, skip the ones that already have peppers on them. A plant fruiting in a four-inch pot is root-bound and stressed. Choose the stocky, dark green one with no flowers. If it has a few, pinch them off when you plant. It feels wrong. Do it anyway, because the plant needs to grow roots before it grows fruit.

Planting day

Harden them off first. Give them a week of increasing time outside: an hour of shade, then a few hours of morning sun, then all day. Skip this and the leaves bleach white within forty-eight hours.

Space plants 18 inches apart. Peppers like to be a little crowded, because their leaves shade each other's fruit and keep it from scalding. A 4x8 bed holds about eight to ten plants. If you're building one, Build a 4x8 Raised Bed for Under Two Hundred Dollars has the plans. Raised beds warm up faster in spring, and for peppers that's a real head start.

Plant at the same depth they sat in the pot, or an inch deeper. Don't bury them to the leaves the way you would a tomato.

Stake them on planting day. A loaded pepper plant is top-heavy, the stems are brittle, and one summer thunderstorm can snap your best plant at the base. A three-foot wooden stake and some soft twine is enough.

In cool areas, lay black plastic over the bed for a week before planting and cut holes for the plants. It raises soil temperature several degrees and buys you time.

Feeding and watering, and where most people overdo it

Go easy on nitrogen. A pepper fed like a lawn turns into a big, gorgeous, dark green bush with almost no peppers on it. Work some compost into the bed at planting and use a balanced or low-nitrogen vegetable fertilizer once flowers appear. That's plenty.

Water deeply and evenly, about an inch a week, more in heat. Peppers get blossom end rot just like tomatoes do. That's the sunken black patch on the bottom of the fruit. It's a calcium problem, but it's almost always caused by uneven watering, not by a shortage of calcium in the soil. Mulch with two or three inches of straw once the soil has warmed up, not before. Mulch put down too early keeps the ground cold.

Hot peppers usually come out hotter if you let the soil dry out a bit between waterings once the fruit is set. Don't push it until the plant wilts. Just stop babying it.

Why the flowers fall off

Every pepper grower panics about this at least once. The plant blooms, and the flowers drop without setting fruit.

It's almost always temperature. Nights below 55°F or days above 90°F make peppers drop blossoms, and bells are the most sensitive. There's nothing to spray. Keep watering and wait. When the weather settles, fruit sets again. In hot climates, some light afternoon shade cloth in July helps.

Peppers pollinate themselves, so unlike squash you don't need bees doing the work. A breeze, or a gentle shake of the plant now and then, is enough.

Picking

Cut peppers off with pruners or scissors. Don't pull them. The branches break easily, and you'll take half the plant with the fruit.

Pick often. A plant loaded with ripening fruit slows down on new flowers. Picking jalapeños green keeps the plant producing. Leaving a few to turn red gives you sweeter, hotter fruit, and you can dry them for chipotle if you've got a smoker.

Wear gloves when you're handling habaneros, and especially when you're cutting them. The heat lives in the white ribs and seeds, and it stays on your fingers for hours, soap or no soap. You'll only rub your eye once.

What we'd buy, what we'd skip

Buy: a soil thermometer, a seedling heat mat if you start from seed, wooden stakes, straw mulch. Jalapeño and Shishito for anybody's first year. Jimmy Nardello if you like to cook.

Skip: pepper cages sold as tomato cages' little brother (a stake does it for less), "bloom booster" fertilizers with a big middle number, and any transplant already holding fruit in its pot.

The plant you don't have to replace

Peppers are perennials where they come from. In fall, before the first frost, dig up your best habanero or jalapeño, cut it back to a foot tall, pot it up and park it in a sunny window or a cool garage under a shop light. Water it sparingly all winter. Plant it back out once the soil hits 60°F, and it'll be fruiting while the seedlings are still catching up.

The best pepper plant in the neighborhood next July might be the one you saved this October.