Growing Amaryllis

amaryllis

Introduction

Amaryllis (Hippeastrum species) is a tender perennial bulb native to Central and South America. It is commonly grown as a houseplant or indoor-outdoor potted plant. Only in very mild climates (zone 8 or warmer) can it be grown outside year round.

Few houseplants can equal or rival the beauty of amaryllis, with its large, lily-like flowers. Varieties are available in a range of heights, flower colors, and flower forms.

Although sometimes treated as a disposable gift plant, amaryllis is actually a long-lived bulb that will grow and flower for many years after planting when given the proper care throughout the season.

Planting

Plant amaryllis bulbs as soon as you can after purchasing. If bulbs cannot be planted immediately, store them at 40 to 50°F.

Use a pot just 1 to 2 inches larger than the diameter of the bulb, as amaryllis likes to be root bound. You will generally need a 6-inch diameter or larger pot for a large-sized bulb. Plant the bulb in a high quality, well-drained peat-based growing medium.

Put a piece of screen, part of a broken clay pot, or a small stone over the drainage hole in the bottom of the pot to prevent potting soil from being rinsed out of the pot when watering.

Fill the pot half full of growing medium and set the bulb with its thickest part about an inch below the rim of the pot. Continue to fill the pot until the bulb is half to two thirds covered and the media is half an inch to an inch below the rim of the pot, to allow for easy watering. The tip, or “neck” of the bulb will remain exposed.

When the pot is filled to the proper level, water thoroughly with lukewarm water. If the media settles after watering, add additional media to bring it to the proper level.

Initial Care

Place the newly planted amaryllis in a sunny location with warm (60 to 80°F) temperatures. Water sparingly, only when the top of the medium is dry, until the flower buds appear. Avoid getting water directly on the exposed portion of the bulb.

Sprouting will generally start 2 to 8 weeks after potting. Turning the pot regularly helps prevent the foliage and flower stems from leaning toward the light. Amaryllis bulbs will usually flower about 6 to 8 weeks after growth begins.

Budding & Flowering

Once buds form, watering can be increased. Keep the medium evenly moist, but not saturated. Especially on tall varieties, support for the flower stalk may be needed to keep flower stems from flopping.

For a longer flowering period, move blooming amaryllis into a somewhat cooler environment, with temperatures of 60 to 65°F. For the longest flower life, keep blooming amaryllis out of direct sunlight.

After Flowering Care

Remove individual flowers from the stalk as they fade. After the last flower dies, carefully cut the flower stalk off a few inches above the bulb.

The leaves usually appear after flowering, and if the foliage droops, it can be staked up if desired.

In order for an amaryllis bulb to rebloom, proper care after flowering is critical. At this point, leaves grow and begin to store nutrients in the bulb to fuel growth the next season. Keeping plants actively growing and not stressed for water or nutrients will ensure they can store the maximum amount of food in the bulb. Keep the pot in a warm, sunny spot and water as needed. Fertilize monthly with a balanced liquid fertilizer (like 6-6-6) to promote vigorous, healthy growth.

After the last spring frost, pots can be moved outdoors and buried in the ground up to their rim in a sunny location. Pots do not need to be buried, but doing so helps them to remain moist. Unburied pots in a sunny location may need watering every day to prevent them from becoming overly dry.

Fertilize plants moved outdoors about every four weeks with a general purpose liquid fertilizer like 6-6-6. Regular fertilization helps to ensure good flowering in future seasons. Pots can also be maintained indoors during the spring and summer in a sunny, warm location. Water as needed and fertilize monthly with a balanced fertilizer solution.

Fall Care & Cooling

Stop fertilizing in late August to early September.

Pots moved outdoors must be brought indoors before the first fall frost.

Amaryllis needs a cool temperature period to rebloom, but does not need to go fully dormant. Allowing plants to go dormant during the cooling period can be used to schedule their reblooming more precisely, by varying the length of the dormant period and when it begins. To have flowering amaryllis in time for Christmas season, plants need to be put into dormancy in August.

To force amaryllis to go dormant, store pots by laying them on their sides in a cool (50 to 55°F), dark location. Do not disturb the foliage or water during this time.

Amaryllis can be kept dormant for 8 to 12 weeks. By this time, the old foliage will have browned and can be removed. Pots can then be brought into a warm, sunny location and watered so that they resume growing.

For plants not put into dormancy, move them into a well-lit, cool (55°F) location and water as needed. Grow at the cool temperature for 8 to 12 weeks. Flowering will usually begin 6 to 8 weeks after plants are moved to warmer (60 to 80°F) conditions.

Repotting

Amaryllis prefers to be root bound and usually only needs repotting every 3 to 4 years. Bulbs should be repotted when there is only about half an inch between the edge of the bulb at its widest point and the side of the pot. The best time to repot is when bulbs are dormant after they have received their cool temperature treatment.

When repotting, any small bulb offsets that have formed can be removed and potted in a 2 or 3-inch pot. Offsets generally take 2 to 3 years to flower after they are separated from the mother bulb. Offsets can also be left on the mother bulb, which will result in more flowers per pot as the offsets mature.

Problem Solving

Amaryllis bulbs that do not flower in their second season may not have had enough stored food reserves to support flowering. Another possibility is that they did not receive a long enough dormant cold period (at least 8 to 10 weeks at 50 to 55°F for most varieties).

Bulbs that do not flower may also be suffering from bulb rot. Gently squeeze the sides of the bulbs to check whether it is still firm. If the bulb has significant “give” or is soft to the touch, it should be discarded. Overwatering can lead to bulb rot.

Occasionally insect pests will attack amaryllis, particularly for plants that spend time outside. Spider mites, mealybugs, and thrips are the most common pests and they can be treated with insecticideal soap. Always follow label directions when using pesticides.


Allen R. Pyle is the lead horticulturalist at Jung Seed Co. and has been a professional horticulturist for over 20 years, with decades of experience in gardening and landscaping. Allen has degrees in both horticulture and entomology from Michigan State University. He has extensive experience in plant propagation, pest management, growing perennials, and organic gardening. His knowledge spans a wide range of plants, including edibles, ornamentals, herbs, weeds, and native species. Allen is passionate about plants and gardening and is always happy to share his knowledge and expertise with others. He regularly speaks and writes on plant-related topics for both professional and amateur gardening audiences. Allen is also certified in Permaculture design.

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