View source for Yarrow

{{SPlantbox
|familia=Asteraceae
|genus=Achillea
|species=millefolium
|taxo_author=L.
|common_name=Yarrow, Milfoil
|name_ref=Flora - A Gardener's Encyclopedia
|habit=herbaceous
|habit_ref=Wikipedia
|Min ht box=.2
|Min ht metric=m
|Max ht box=1
|Max ht metric=m
|height_ref=Wikipedia
|Min wd box=.45
|Min wd metric=m
|Max wd box=.75
|Max wd metric=m
|width_ref=Flora - A Gardener's Encyclopedia
|poisonous=rare skin allergies
|poison_ref=Wikipedia
|lifespan=perennial
|life_ref=Wikipedia
|exposure=sun, part-sun, shade
|sun_ref=Plants for a Future
|water=moderate, dry
|features=flowers, fragrance, naturalizes, invasive, bees, drought tolerant, ground cover, fire resistant
|flower_season=early summer, mid summer, late summer
|flower_ref=Flora - A Gardener's Encyclopedia
|flowers=red, yellow, white
|Min Temp Num=-25
|Temp Metric=°C
|temp_ref=Plants for a Future
|min_zone=3
|usda_ref=Flora - A Gardener's Encyclopedia
|max_zone=10
|image=Achillea millefolium 20041012 2574.jpg
|image_width=200
}}
'''Yarrow''' ('''Common Yarrow''', '''Gordaldo''', '''Nosebleed plant''', '''Old Man's Pepper''', '''Sanguinary''', '''Soldier's Woundwort''', '''Thousand-leaf''', '''Thousand-seal'''; '''''Achillea millefolium''''') is a [[flowering plant]] in the family [[Asteraceae]], native to the [[Northern Hemisphere]]. 

Common yarrow is an erect [[herbaceous]] [[perennial plant]] that produces one to several stems (0.2 to 1m tall) and has a [[rhizomatous]] growth form. Leaves are evenly distributed along the stem, with the leaves near the middle and bottom of the stem being the largest. The leaves have varying degrees of hairiness (pubescence). The [[leaf|leaves]] are 5–20 cm long, [[pinnate|bipinnate or tripinnate]], almost feathery, and arranged spirally on the stems. The leaves are [[cauline]] and more or less clasping. The inflorescence has 4 to 9 [[bract|phyllaries]] and contains ray and disk flowers which are white to pink. There are generally 3 to 8 ray flowers that are ovate to round. Disk flowers range from 15 to 40. The inflorescence is produced in a flat-topped cluster. Yarrow grows up to 3500m above sea level. The plant commonly flowers from May through June, and is a frequent component in [[butterfly garden]]s. Common yarrow is frequently found in the mildly disturbed soil of grasslands and open forests. Active growth occurs in the spring.

Common yarrow is a drought tolerant species of which there are several different ornamental cultivars. Seeds require light for germination, so optimal germination occurs when planted no deeper than ¼ inch. Seeds also require a germination temperature of {{convert|18|-|24|C|F}}. Common yarrow responds best to soil that is poorly developed and well drained. The plant has a relatively short life, but may be prolonged by dividing the plant every other year, and planting 12 to 18 inches apart. Common yarrow is a weedy species and can become invasive.<ref>USDA, NRCS. 2006. The PLANTS Database (http://plants.usda.gov, 22 May 2006). National Plant Data Center, Baton Rouge, LA 70874-4490 USA.[http://plants.usda.gov/java/profile?symbol=ACMI2]</ref>  It may suffer from mildew or root rot if not planted in well-drained soil.

{{Inc|
Achillea millefolium, Linn. Milfoil. Yarrow. Height 1-3 ft.: lvs. bipinnately parted, segms. linear, 3-5 cleft: fls. in flat corymbs. June-Oct. Eu.,Asia, Amer. Common in pastures. — Less commonly cult., than vars. rubrum and roseum, with red or purple fls.
{{SCH}}
}}

==Cultivation==
Succeeds in most soils and situations but prefers a well-drained soil in a sunny position[1, 14]. Shade tolerant[13]. Plants live longer when grown in a poor soil[200] and also do well on lime[208]. Established plants are very drought tolerant[200], they can show distress in very severe droughts but usually recover[190]. It remains green after grass has turned brown in a drought[187]. Plants succeed in maritime gardens[233]. The plant has a very spreading root system and is usually quite invasive[233, K]. A very hardy plant, tolerating temperatures down to about -25°c[187]. Yarrow is an excellent plant for growing in lawns, meadows, orchards etc., it is tolerant of repeated close cutting and of being walked on[20, 54]. It works to improve the soil fertility[20, 54]. A very good companion plant, it improves the health of plants growing nearby and enhances their essential oil content thus making them more resistant to insect predations[14, 18, 20, 53]. There are some named forms, selected for their ornamental value[183, 238]. 'Pink' (syn. 'Rosea') has very aromatic foliage and deep pink flowers[183]. Hybridizes freely with other members of this genus[200]. A good bee plant, it is an important nectar source for many insects[24].

===Propagation===
Seed - sow spring or early autumn in a cold frame[133]. The seed usually germinates in 1 - 3 months[133]. When large enough to handle, prick the seedlings out into individual pots and plant them out in the summer. Division in spring or autumn. Very easy, the divisions can be planted direct into their permanent positions. Divisions succeed at any time of the year. Basal cuttings of new shoots in spring. Very easy, collect the shoots when they are about 10cm tall, potting them up individually in pots and keeping them in a warm but lightly shaded position. They should root within 3 weeks and will be ready to plant out in the summer.

===Pests and diseases===


==Varieties==
The species is generally too weedy for gardens but cultivars include 'Paprika', 'Cerise Queen' and 'Red Beauty'; and the many hybrids of this species designated ''Achillea'' x ''taygetea'' including 'Appleblossom', 'Fanal' and 'Hoffnung' are useful garden subjects.<ref>Perennials for American gardens, 1989, Random House, ISBN 0-394-55740-9</ref>

There are several [[variety (biology)|varieties]] and [[subspecies]]:
*''Achillea millefolium'' subsp. ''millefolium''
**''Achillea millefolium'' subsp. ''millefolium'' var. ''millefolium'' - [[Europe]], [[Asia]]
**''Achillea millefolium'' subsp. ''millefolium'' var. ''alpicola'' - [[Rocky Mountains]]
**''Achillea millefolium'' subsp. ''millefolium'' var. ''borealis'' - [[Arctic]] regions
**''Achillea millefolium'' subsp. ''millefolium'' var. ''californica'' - [[California]]
**''Achillea millefolium'' subsp. ''millefolium'' var. ''occidentalis'' - [[North America]]
**''Achillea millefolium'' subsp. ''millefolium'' var. ''pacifica'' - west coast of [[North America]]
**''Achillea millefolium'' subsp. ''millefolium'' var. ''puberula'' - California
**''Achillea millefolium'' subsp. ''millefolium'' var. ''rubra'' - Southern [[Appalachians]]
*''Achillea millefolium'' subsp. ''chitralensis'' - western Himalaya
*''Achillea millefolium'' subsp. ''sudetica'' - Alps, Carpathians

==Gallery==
<gallery perrow=5>
Image:Achilleamillefolium.jpg
Image:Achillea millefolium.jpg
image:mp-Achillea millefolium.jpg
image:red_Achillea_millefolium.jpg
</gallery>

==References==
<references/>
*[http://www.pfaf.org/database/plants.php?Achillea+millefolium Plants for a Future] - source of some creative commons text
*[[Standard Cyclopedia of Horticulture]], by L. H. Bailey, MacMillan Co., 1963
<!--- xxxxx  *Flora: The Gardener's Bible, by Sean Hogan. Global Book Publishing, 2003. ISBN 0881925381  -->
<!--- xxxxx  *American Horticultural Society: A-Z Encyclopedia of Garden Plants, by Christopher Brickell, Judith D. Zuk. 1996. ISBN 0789419432  -->
<!--- xxxxx  *Sunset National Garden Book. Sunset Books, Inc., 1997. ISBN 0376038608  -->

==External links==
*{{wplink}}

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