Skip to Main Content

LuEsther T. Mertz Library
Plant & Research Guides

Popular Houseplant Profiles: D - G

Euphorbia pulcherrima - poinsettia

Euphorbia pulcherrima (poinsetta); photo courtesy of Flickr cc/ Maurizio
Euphorbia pulcherrima (poinsetta); photo courtesy of Flickr cc/ Maurizio

Poinsettia is possibly the most popular of all holiday plants. The tiny, inconspicuous flowers are surrounded by large, colorful bracts of bright red, pink, or creamy white. Although poinsettias have been vastly improved, they are still temperamental as houseplants and require very particular cultural practices to keep on after the holidays.

Cultural Requirements

Light:

Poinsettias require four hours of direct sunlight a day.

Watering:

Water the poinsettia thoroughly when the top few inches have dried out. Do not allow the plant to wilt, as this will cause inherent weakness and lead to quick demise.

Temperature:

Poinsettias do best in night temperatures between 55° to 65°F and day temperatures between 65° to 70°F. Avoid warm and cold drafts as rapid water loss will result in wilt and leaf drop.

Humidity:

A relative humidity above 50% is preferred to successfully grow poinsettias. Additional moisture can be provided by setting the plant on a tray of pebbles that is kept moist and/or using a humidifier.

Feeding:

Unless the plant is to be forced or grown from cuttings for future holidays, extra fertilization in unnecessary. For plants to be grown on, feed with a water soluble, all-purpose, liquid fertilizer twice a month during the growing season (March through September).

Transplanting:

When pot bound, move the plant into the next largest pot size. If the plant is in a plastic pot move it into a new plastic pot; if it is growing well in a clay pot move it into a new clay pot. The soil mix preferred by poinsettia is equal parts sterilized houseplant potting soil and coarse builder's sand or perlite.

Propagation:

Tips of healthy side shoots that have not produced flower bracts make the best cuttings. Make a 3 to 4"cutting just above a node, let it harden-off so that no milky sap oozes and place it into a small glass of water. Change the water often and keep the cutting in a warm

Maintenance:

In order to induce a poinsettia into bloom for the next season, grow it in a sunny location. After all danger of frost is past it can be grown in a partially sunny location outside. Continue to fertilize it and be sure to pinch back the growing tips to induce bushiness. Bring it back indoors before frost and subject it to 14 hours of total darkness each night until the bracts begin to show color. Then it can be brought into the light and treated as a houseplant.

Special Note:

The darkness must be uninterrupted each night or the buds will fail to form. To insure success, keep the night temperatures low and don't forget to expose the plant to light each day after the 14 hours of darkness.

Gardenia jasminoides - gardenia

Gardenia jasminoides (Gardenia); photo courtesy of Flickr cc/Forest and Kim Starr
Gardenia jasminoides (Gardenia); photo courtesy of Flickr cc/Forest and Kim Starr

Gardenias are beautiful, shrubby, evergreen houseplants well loved for their creamy, fragrant blooms. They are temperamental in cultural requirements and respond best to cool temperatures, high humidity, constant soil moisture and bright to full sunlight.

Cultural Requirements

Light:

Gardenias need at least 4 hours of direct sunlight a day.

Watering:

They prefer to be consistently moist. In order to reduce excess fertilizer salts in the soil, water with distilled water once a month.

Temperature:

Cool temperatures are preferred, 65° to 70°F during the day and below 65°F at night. High temperatures will result in leaf and flower bud drop.

Humidity:

Gardenias grow best with extra humidity. Provide extra moisture with daily misting, set the plant on a tray of moist pebbles and/or use a humidifier. Extra humidity is important in keeping down spider mites that thrive under dry conditions.

Feeding:

During the growing season (March through September), fertilize gardenias every two weeks with a dilute fertilizer for acid-loving plants.

Transplanting:

When it is necessary to transplant, use a soil mixture of two parts peat moss, one part sterilized houseplant potting soil and one part sand or perlite.

Propagation:

Propagate gardenias in early spring with 3 to 4" stem cuttings just below a leaf node. Dip the end of the stem cutting into a rooting hormone, place it into a light mix of soil with perlite and keep it moist. Transplant the rooted cuttings into 3" pots with the preferred growing mix as described above.

Maintenance:

To encourage continuous blooming, cut off the faded flowers to just below the leaf node, maintain a cool (below 65°F) night temperature, and feed with a dilute fertilizer with iron every two weeks during the growing season. In addition, keep the humidity level high and prune/shape the plants in early spring to encourage branching and compact growth.

Special Note:

Monitor and treat insect and mite pests as soon as possible. Avoid leaf and flower bud drop by keeping night temperatures cool, providing high humidity and giving sufficient light.

JUMP TO TAB 'H'

Ask a Plant Expert

Contact Us

with your plant questions by email

plantinfo@nybg.org

Find a Plant at NYBG

Find a Plant at NYBG

Map of NYBG

Noteworthy Books on Houseplants

Related Plant Societies

Image result for euphorbia society logo