Watering and care

Once chiles are in the ground or in their final pots, most of the work is watering. Get that right and the rest is light: a layer of mulch, a cane or cage for big plants, and the odd pinch. This chapter covers that routine, plus how to keep a favourite plant alive through winter so it can crop again.

How much and how often to water

Water per week

2.5–5 cm (1–2 in), applied deeply and infrequently⁵

After fruit set

At least 5 cm (2 in) a week in dry spells²

Wet the soil to

At least 15 cm (6 in) deep³

Mulch depth

7.5–10 cm (3–4 in) of straw, grass clippings or other organic material⁴

Pot, compact chile

One plant per 22 cm (9 in) pot⁶

Pot, dwarf pepper

At least 15–23 L (4–6 gal) of mix, 20–30 cm (8–12 in) deep⁸

Pot, full-size pepper

At least 30–38 L (8–10 gal) of mix, 30–40 cm (12–16 in) deep⁸

The aim is even moisture. New Mexico State University puts the goal of watering as a uniform soil moisture level that promotes uniform growth and fruit set. Too little water makes plants shed blossoms and causes smaller fruit and blossom-end rot; too much leads to Phytophthora root rot, which makes a plant wilt and die suddenly.¹

For plants in the ground, Utah State recommends watering deeply and infrequently, 2.5–5 cm (1–2 in) a week.⁵ Minnesota’s rule is similar: if rain doesn’t supply 2.5 cm (1 in) in a week, soak the soil thoroughly at least once that week, and water more often on sandy soil.⁴ Clemson says to wet the soil to at least 15 cm (6 in) deep each time.³ A rain gauge, or an empty straight-sided can left in the bed, tells you how much has fallen.

Avoid light sprinkles. Minnesota warns that watering which only wets the surface grows shallow roots, leaves plants more vulnerable to heat and drought, and lowers fruit quality.⁴

Guides differ on how dry the soil may get between waterings. Utah State says to let it dry between waterings,⁵ while Clemson says not to let it dry out.³ Both want the same result: a deep soak, then no more water until the plant needs it, with the soil never soggy and never baked dry. The simplest check is Clemson’s: feel the soil to find out whether it is still damp.⁹ If it is damp below the surface, wait.

How to water

• Drip or soaker hose. NMSU calls drip irrigation the most efficient way to water chiles; sprinklers and furrows work but make water and disease harder to manage.¹ Maryland also recommends drip and soaker hoses.⁷
• Keep leaves dry. Minnesota advises against overhead sprinkling because wet leaves are more prone to disease,⁴ and Utah State warns especially against overhead watering late in the day.⁵

Watering by stage and weather

Seedlings and new transplants have their own needs, covered in the Seed starting chapter: cutting back on water while hardening off, watering plants well before transplanting and watering them in afterwards.

Once plants are established, the stage that matters most is flowering and fruiting. Clemson calls fruit set and fruit development the critical period for moisture.³ The Chile Pepper Institute recommends at least 5 cm (2 in) of water a week in dry spells, especially after fruit set,² the top of Utah State’s range. Running short of water at this stage brings on blossom-end rot;¹ the Nutrients chapter explains the link with calcium.

Hot, dry weather

Heat raises demand fast. The RHS warns that flower buds may fall off if plants get too dry,⁶ and Maryland lists blossom drop, small fruit and blossom-end rot as results of dry conditions.⁷ In a heatwave, check plants every day. Pots may need watering daily or twice a day; Clemson suggests checking containers at least once a day and twice on hot, dry or windy days.⁹ Maryland also suggests a spot with some late-afternoon shade and cooling plants with a water spray during hot, dry weather.⁷ The Climate chapter covers heat stress, including NMSU’s warning that blossoms may not set above 32 °C (90 °F).¹

Cool or wet weather

In cool or rainy spells, over-watering is the bigger risk. Let rain count toward the weekly total, feel the soil before adding more, and never leave plants sitting in waterlogged ground: that is what brings on Phytophthora root rot. NMSU says drip irrigation and raised beds help manage water and so reduce it.¹ The Soil chapter covers drainage.

Mulch

Mulch evens out soil moisture. Clemson says it helps retain consistent soil moisture, conserve water and reduce weeds,³ and NMSU says combining drip irrigation with a plastic or organic mulch saves a lot of water while still supplying plenty for the crop.¹

• Early season: black plastic. Black plastic mulch warms the soil, conserves water and helps control weeds.⁵ NMSU recommends it for warming the soil early in the season.¹
• Once the soil is warm: organic mulch. Utah State says to wait until the soil is warmer than 24 °C (75 °F) before putting straw, grass clippings or newspaper around plants.⁵ NMSU suggests replacing black plastic with organic mulch when the weather warms, since straw, dry grass clippings and leaves help cool the soil in hot weather.¹
• Depth. Minnesota suggests herbicide-free grass clippings, weed-free straw or other organic material 7.5–10 cm (3–4 in) deep to help prevent weeds.⁴
• Materials. Maryland lists straw, dry grass clippings and raked autumn leaves, with sheets of newspaper laid underneath for even better weed control.⁷ Make sure grass clippings come from a lawn that hasn’t been treated with herbicide.⁴

Pots benefit too: Clemson notes that mulch and windbreaks can reduce how much water containers need.⁹

Containers and pot sizes

The Soil chapter covers container mix and drainage. The other decision is size. Maryland’s advice is to match the container to the plant, both top growth and roots, because restricting the roots too much means the plant won’t grow well.⁸

These figures span a wide range. The RHS’s 22 cm (9 in) pot is the smallest,⁶ while Maryland’s figures are for peppers that can reach 90–120 cm (3–4 ft).⁷ Go bigger when you can. A small volume of soil dries out very quickly, especially on a concrete patio in full sun,⁹ so a larger pot means more forgiving watering as well as a larger plant.

• Drainage holes are essential. Not every commercial pot has them, so check before planting.⁸
• Material matters. Pots made of porous materials such as clay, ceramic, concrete and wood dry out faster than plastic or metal ones.⁸
• Water until it drains. Apply water until it runs out of the drainage holes.⁹
• Lift pots off hot paving. Clemson suggests standing containers on pallets or similar so air moves underneath and they don’t touch the hot cement.⁹

Plants in pots also run through the nutrients in their compost; the Nutrients chapter covers liquid feeding.

Staking and support

Chile stems can be brittle, so big plants need help staying upright. The RHS says large plants and those in growing bags may need support: use several canes per plant and tie the stems in carefully, as they can be brittle.⁶ Maryland recommends cages or short trellises, noting that pepper plants can reach 90–120 cm (3–4 ft).⁷

By the same token, smaller plants in the ground may manage without support. Brittle stems are also a reason to harvest with care: Maryland says to cut pods off rather than pull them, to avoid breaking branches.⁷

Pruning and pinching

Chiles don’t need regular pruning. Two kinds of pinching are worth knowing about.

• Early flowers. Maryland recommends pinching out early flower buds and small fruits to produce stronger, more prolific plants.⁷ The Seed starting chapter covers flowers on transplants.
• Growing tips. The RHS says pinching out isn’t usually needed, but it can be done once plants reach about 30 cm (1 ft) tall to get a bigger crop of smaller fruits. The trade-off is that pinching can delay fruiting.⁶ In a short season, weigh that delay before you pinch.

Otherwise, keep the plant leafy. Minnesota notes that sunscald damages fruit exposed to intense direct sun, as on small plants with a gap in the leaf canopy.⁴ The Climate chapter covers sunscald in more detail.

Overwintering chiles as perennials

Chiles are perennial sub-shrubs from South America, grown as annuals wherever it freezes. The Chile Pepper Institute notes that in the continental US they can be grown as perennials in only a couple of places: southern California, Florida, a very small part of South Texas and a small area of southern Arizona.² Maryland describes the pepper as a very tender warm-season perennial whose top growth is injured by frost.⁷ In a frost-free climate, a plant can simply stay where it is. Everywhere else, the only way to keep one is to bring it indoors.

Bringing a plant indoors

Plants already growing in pots are the practical candidates, since they can be carried in without disturbing the roots. The RHS says to prune overwintering chiles back to a manageable size, then keep them in a warm, bright place such as an indoor windowsill or conservatory and water sparingly.⁶ Iowa State’s general method for tender plants kept as houseplants fills in the rest:¹⁰

1. Bring the plant inside before a hard freeze.¹⁰
2. Place it in a sunny spot, away from drafts, and water when the soil is dry.¹⁰
3. Check regularly for pests.¹⁰
4. Toward the end of winter, begin feeding every 2–4 weeks to prepare the plant for going back outside.¹⁰
5. Move it back outside after the last frost, acclimatising it to outdoor light gradually over 2–3 weeks.¹⁰ The hardening-off steps in the Seed starting chapter work here too.

In the Southern Hemisphere the steps are the same with the seasons reversed: bring plants in ahead of your first autumn frost and put them out after your last spring frost. The Zones and seasons chapter explains how to find those dates.

Watering, mulching and support are most of the season’s work. Pests, diseases and knowing when to pick are covered in the next chapter, Problems and harvest.