Culture tips for ‘Alternanthera ‘Purple Knight’

April 2, 2002 - 13:39

Combine Purple Knight with any plant to produce beautiful hanging baskets.

Alternanthera ‘Purple Knight’ comes from a genus
of about 200 species of bushy annuals and perennials. This variety is a
striking, dark purple-leafed accent plant with a vigorous, upright and
spreading habit that arches over the edge of containers. It has exceptional
heat tolerance and even thrives in conditions such as subtropical summers.
Although the foliage is darkest in full sun, Purple Knight performs well in
full sun to partial shade.

Its colorful, oppositely arranged leaves are generally
linear to oval, often with toothed margins, and vary in size. Purple Knight
will flower under short days; the flowers are small and are formed in terminal
and axillary spikes. Plants adapt easily and are best used as annuals in summer bedding, in an edging or as a backdrop in the landscape. They are excellent massed in hanging baskets and combine well with just about any plant.

Alternanthera Purple Knight is one of five foliage items new
for summer 2002 that were traditionally only available as cuttings, but can be
ordered as seeds or plugs. Seed will be available in August.


Seeds should be covered lightly with a coarse vermiculite.
Germinate Purple Knight seeds at a temperature of 72-76° F and maintain 95
percent relative humidity until cotyledons emerge. For more uniform
germination, provide light in the germ chamber or germinate on the bench; light
increases germination uniformity. Keep soil moisture high until radicle
emergence, then reduce moisture levels after the radicle penetrates the medium.

Do not allow the seedlings to wilt. Growth regulators are
not needed to produce top-quality Purple Knight plugs. While growing the plugs,
temperatures should be in the range of 65-72° F. Plugs can be held at
62-65° F.

Growing On

Purple Knight is a very easy and quick crop to grow at 8-9
weeks from sow to finish. Growers should use a well-drained, soilless medium
with a pH of 5.5-6.3 and a medium initial nutrient charge (EC 0.75 mmhos/cm
with a 1:2 extraction).

This variety is a moderate feeder; fertilize plants weekly
with 200 ppm nitrogen in a complete fertilizer. Growth regulators are generally
not needed; however, if necessary, a Bonzi spray at about 30-45 ppm is
effective in controlling height and spread.


When finishing Purple Knight plugs, allow 4-5 weeks from
transplant to finish in a 4-inch container from a 392-plug tray. Using larger
plug sizes will reduce crop time. Night temperatures should be kept at
62-65° F; increase day temperatures slightly to 65-75° F.

Purple Knight can tolerate drier conditions once
established, but to avoid damage to leaf tissue, irrigate plants before they
are severely wilted.

About The Author

Scott Rusch is a sales specialist for PanAmerican Seed, West Chicago, Ill. He may be reached by phone at (630) 588-3464 or E-mail

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