Indoor Pineapple Culture

In 2008, I replaced my 400 watt HID Metal Halide lighting system with a more energy efficient six bulb T5 high output fluorescent lighting system. Each bulb is 54 watt, 5,000 lumens with a color temp of 5000K.

The pineapple (Ananas comosus) belongs to the bromeliaceae family. It is a terrestrial (soil growing) bromeliad, and it is native to the tropical and warm subtropical regions of Brazil and Paraguay.

The pineapple is a slow-growing, herbaceous, perennial herb. It has a short stem which is covered by long, narrow, sword-shaped leaves arranged in a rosette pattern. Some varieties have spines along the leaf edges. The plant grows about 3 feet (100cm) in height and spreads up to 5 feet (152cm). A large plant can have as many as 80 leaves. At the time of flowering, a flower stalk appears from the plant's center bearing a reddish cone-shaped leaf cluster. A purple or red flower appears between each leaf. Flowering starts from the bottom and progresses towards the top. No special pollination is required. The fruit is seedless; however, if two different varieties are grown near each other, the cross pollination produces tiny black seeds. The fruit slowly develops and ripens in 4 to 5 months after flowering.

Obtain a pineapple fruit that has an unbruised, dark green leafy crown. Hold the fruit and grab the crown at the base and remove it by twisting it off. Pull a few of the bottom leaves off until 3/4" to 1" ( 1.9 to 2.5cm) of the stem is exposed. Along the exposed stem, roots will form. Set the crown aside for a few days in a warm, airy place out of direct sunlight until a callous forms. After that, the crown is ready to be planted.

Plant the crown in a 10" (25cm) pot. The best soil for pineapples is a well-drained, moisture retentive, acidic mix with a high organic matter content. A potting mix of 1 part peat moss, 1 part perlite, and 1 part leaf mold or worm castings works well. Gently firm the soil up around the crown's base to support it. Move to a warm, bright area with filtered sunlight. Keep the soil moist, not wet. About 4 to 6 weeks later, the leaves will begin to grow out. Gradually introduce to full sun.

Pineapple plants have a high demand for nitrogen, potassium, and iron. They grow very well when needed elements are supplied at a slow, constant rate. Apply a slow release, non-burning fertilizer to the soil every 3 months or water with a very weak fertilizer solution at every watering.

If you're into organic gardening, there are several fertilizers you can use. Pineapples respond well with quarterly applications of blood meal (nitrogen), bone meal (phosphorus), and sulpomag (potassium/magnesium). Rock powder should be added to supply trace minerals.

Do not use any products that contains alfalfa meal or cottonseed meal. Anthracnose is known to attack alfalfa and cotton, and there is a strong possibility that you could introduce your plants to this fungal disease which causes leaf spots.

There seems to be a common misconception that all bromeliads like water poured in the center of the plant. This is not true! The "tank" bromeliads, like Aechema fasciata, need water held in the center. When water remains in the center of a pineapple plant, it can lead to rot. Water the soil thoroughly until it drains into the bottom saucer. Don't let water stand in saucer. Allow the soil to dry slightly between waterings.

Bromeliads like the pH of the water to be slightly acidic. Check with your local water department to find out about the pH. If your water is hard (alkaline), add 1 tsp of vinegar per quart of water.

Pineapples enjoy evenly warm temps all year. A warm area above 70°F (21°C) is needed for good, steady growth. Move plants outdoors when both days and nights are consistently warm. Plants can tolerate occasional lows in the 50's (10°C - 15°C), but prefer 60's (16°C - 20°C). Highs should be 75°F to 90°F (24°C to 32°C). When temperatures reach 90°F (32°C) or more, plants should be placed in filtered sunlight to avoid sunburn.

Humidity can be a problem indoors during the heating season. The humidity level should be maintained at 50% to 55%. A room humidifier placed on a timer provides an effective way of maintaining humidity levels.

Having adequate light indoors is absolutely essential for good growth and fruiting. Pineapple plants require at least 12 hours of bright light a day. Artificial lighting should be used as a sole light source or as a supplement to natural daylight.

High intensity discharge lighting and T5 high output fluorescent lamps offer the best quality light. Check out my online garden suppliers page.

When it is time for your pineapple plant to go outdoors for the summer or indoors for the winter, it needs to be acclimated to its new environment. The plant should gradually be introduced to more shade over a period 3 weeks before going indoors. When going outdoors, place plant under a shade cloth or in an area that only receives the weak morning or evening sun. Over a period of 3 weeks, gradually introduce to more sunlight.

When leaves start getting out of bounds, prune them back with a sharp pair of scissors. Cut the leaf straight across then shape the cut like an arrow. This will make the pruned leaf look more natural. To remove yellowing and dead leaves, split them straight down the middle and pull apart from the stem.

Indoor pineapple plants are not usually bothered by many pests or diseases. However, mealy bugs and scale insects do attack them. These pests can be effective controlled by using a 1% to 2% light horticultural oil spray.

Diseases that appear on indoor pineapple plants are sometimes due to incorrect cultural practices. Overwatering can cause root rot. Heart rot can happen if water is poured and allowed to stay in the plant's center for long periods of time. Leaves staying wet from misting without adequate air circulation can encourage leaf spot disease if spores are present.

Troubleshooting Pineapples
Symptoms	Probable Causes	Solutions
Leaf edges curl under	Low humidity, underwatering, acclimation	Buy humidifier to increase relative indoor humidity, water when the top 2" (5cm) of soil is moderately dry, gradually introduce plant to new environment
Brown spots on leaves	Fertilizer burn, salts in water	Fertilizer solution shouldn't be over 200ppm, use distilled water or clean rainwater
Small brown or black lesions on leaves	Fungal infection, Anthracnose	Cool, wet conditions favor growth, avoid wetting leaves, temps above 80°F retard fungal growth, use a fungicide
No plant growth	Cool temps, rootbound, underwatering, low light or not enough light	Temp over 70°F (21°C) needed for good growth, check rootball, water when the top 2" (5cm) of soil is moderately dry, move to brighter area
Brown leaf tips	Low humidity, fertilizer burn, too cold	Buy humidifier to increase humidity, fertilizer solution shouldn't be over 200ppm, minimum temperature 60°F (16°C)
Fruit not large	Plant was forced to bloom when young, inadequate leaf surface	Force bloom when the plant has a minimum of 40 mature leaves on it. Each leaf should measure over 18" (46cm) long. This insures a decent fruit size.
Yellowish, white, or red spots on leaves	Mealy bugs or scale insects	Look for pests in leaf axils and treat with a light oil spray.
Lower leaves yellow and dry up	Underwatering, rootbound, acclimation (high light to low light), dimming artificial light	Water when the top 2" (5cm) of soil is moderately dry, check rootball and repot if necessary, gradually introduce plant to a new environment, change light bulb
Yellow-green leaves	Nitrogen deficiency, rootbound, root rot, improper acclimation- low light to high light	Use a highly diluted 2-1-2 fertilizer, check rootball and repot if necessary, gradually introduce plant to a new environment

Flowering occurs naturally in mature plants when the days are short and cool. However, pineapple plants seldom flower on their own under indoor cultivation. A technique called "forcing" has to be used to initiate the flowering cycle.

Forcing can be achieved by using chemical hormones, calcium carbide, acetylene gas, or ethylene gas. Chemical hormones such as Ethephon, Florel, and Omaflora are used commercially. Calcium carbide needs to be handled with caution. It is used to saturate water with acetylene gas (flammable). The treated water is added to the plant. Ethylene gas is produced naturally from apples, pears, peaches, and other fruits. To maximize ethylene exposure, enclose the plant in a large, clear plastic bag with 2 or 3 fruits for one week. Approximately 45 to 60 days later, a flower cluster should appear in the plant's center. Forcing is most effective when done during cool temperatures (mid to upper 60's/16°C-21°C).

For maximum sweetness and flavor, it is best to pick the fruit when it is fully ripe. Once the fruit is harvested, it will not improve in quality! Depending upon the variety grown, a ripe pineapple can either be yellow-orange, orange-red, yellow, red, green, or purple. To harvest fruit, use a sharp knife or pruning shears and cut stalk one inch below the fruit.

Pineapple plants, like all bromeliads, slowly fade away after flowering. Before this happens, the plants will produce one or more types of leafy offshoots: crowns, slips, suckers, and ratoons. Crowns are shoots which grow on the tops of the pineapple fruits. Slips are shoots which grow on the flowering stalk. Suckers (above photo) are shoots which originate from the leaf axils on the stem, and ratoons are suckers that grow from the stem below soil level.

Crowns should be the first type of propagating material used if you want to establish new plants quickly. Suckers and ratoons are generally larger, stronger, and bear fruits sooner. Remove them with a sharp, serrated knife when half the size of the mother plant. Plant suckers the same way as crowns.

Cayenne or Smooth Cayenne

Cayenne is the industry standard. It is the most widely grown variety in the world. The plant is large with nearly spineless leaves that take on a reddish coloration in strong light. It can bear fruit weighing up to 6 lbs (3kgs). The fruit is high in sugar, acid and fiber. Cayenne is the main processing and canning variety. Good for fresh eating.

Gold Extra Sweet (MD-2 Hybrid)

This variety is a hybrid of Smooth Cayenne. The plant is large and vigorous with nearly spineless leaves. The fruit is smaller than Cayenne, and it has an orange-yellow shell when ripe. The flesh is yellow, very sweet, and low in acid.

Natal Queen

This plant is small and compact with spiny leaves that become tinged with a reddish-purple coloration in strong light. The fruit weighs up to 2 lbs (1 kg) and has a golden-yellow shell when ripe. The flesh is yellow, sweet, and pleasantly crisp. It stores very well. Good for fresh eating.

Red Spanish

This variety is grown mostly in the Caribbean. The plant has spiny leaves with a reddish coloration. The fruit has an orange-red shell when ripe and can weigh 2 to 4 lbs (1 to 2 kgs). The flesh is pale yellow, slightly acidic, fragrant, and rich.

Pérola

This variety is grown extensively in Brazil. The plant is medium sized and a vigorous grower with spiny, dark green leaves. It produces conical-shaped fruit weighing up to 2 lbs (1 kg). The fruit has a green shell with yellow eyes when ripe. The flesh is white, tender, fragrant, high in sugar, and rich in flavor. Outstanding for fresh eating!

Kona Sugarloaf

This plant has no leaf spines and produces fruit that weighs up to 6 lbs (3 kgs). The fruit has a yellow-orange shell when ripe. The flesh is white, juicy, high in sugar, no acid, rich in flavor with an edible core. Outstanding for fresh eating. Highly recommended!

Pernambuco

This plant has spiny leaves and produces fruit that weighs 2 to 4 lbs (1-2 kgs). The fruit has a greenish-yellow shell when ripe. The flesh is pale yellow to white, juicy, high in sugar rich in flavor. Outstanding for fresh eating!

Queen Victoria

The plant is small and compact with spiny leaves. The fruit is small, weighs up to 1 lb (.5 kg) and it has a yellow-orange shell when ripe. The flesh is yellow, richly flavored, very sweet, and coreless. Outstanding for fresh eating!

Pineapple Update

Plant Description

Crown Preparation

Planting

Fertilizing

Watering

Temperature/Humidity

Light

Pruning

Pests and Diseases

Flowering and Fruiting

Harvesting

Propagation

Varieties

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