Lavender can be a rewarding addition to Iowa and other Upper Midwest gardens, but success depends on selecting the right species and providing suitable growing conditions. Cold winters, wet soils, and variable spring weather limit many lavender types. With careful plant selection and proper care, gardeners can grow lavender successfully to use as a fragrant herb, a pollinator support, and an ornamental.
Site Selection & Planting | Care | Harvest & Use | Species & Cultivars | Propagation | Potential Problems | Overwintering | More Information
Site Selection and Planting
Lavender requires full sun and soils with excellent drainage. Plants need at least six to eight hours of direct sunlight each day to maintain compact growth and produce abundant flowers. Good air movement helps reduce humidity around the foliage and lowers disease risk.
Soil conditions directly affect plant survival. Lavender grows best in sandy or loamy soils that drain quickly. Heavy or poorly drained soils often lead to root rot and winter loss. Raised beds or berms improve drainage and are often necessary in clay soils. Lavender also prefers neutral to slightly alkaline soil, and adding lime can help if soils are too acidic. Alternatively, lavender can be grown in containers. Container-grown plants will not overwinter well but can be enjoyed as annuals or brought indoors for the winter.
Planting should take place in spring after the risk of severe frost has passed. Plants should be set at the same depth as they were in the container and spaced to allow good air circulation as they mature.
Care
Lavender requires minimal care once established. Established plants are quite drought-tolerant, but newly planted lavender benefits from regular watering during the first growing season. In general, overwatering is more problematic than underwatering because saturated soils promote root diseases.
Fertility needs are low. High levels of nitrogen result in excessive vegetative growth and fewer flowers. In most cases, lavender performs best without fertilization.
Pruning helps maintain plant shape and encourages branching. Light pruning after flowering supports additional growth and keeps plants compact. In spring, gardeners should remove dead or damaged stems. Cutting into woody portions of the plant should be avoided, as lavender does not readily produce new growth from old wood.
Harvest and Use
Harvest stems just as the flower buds begin to open for the best fragrance and oil content. Cut in the morning, after the dew has dried, and gather the stems into small bundles. Hang them upside down in a warm, dry, well-ventilated area out of direct sunlight to dry. Proper harvest timing and careful drying help preserve both color and fragrance.
Once dry, the flowers can be stripped from the stems and used in a variety of ways. Gardeners commonly use lavender in sachets, potpourri, floral arrangements, and culinary applications such as teas, baked goods, and herb blends. Lavender also has a long history in soaps and essential oil production.
Lavender Species and Cultivars
Not all lavender can tolerate Iowa conditions. Winter hardiness and tolerance to wet soils are the primary limiting factors. Additional information on cultivars potentially well-suited for Iowa beyond those listed below can be found in this article from the Chicago Botanic Gardens: Lavenders for Northern Gardens.
English Lavender (Lavandula angustifolia)
English lavender is the most reliable option for cold climates. It tolerates winter temperatures better than other species and performs well with proper drainage, which can be difficult to find sometimes in Iowa's heavy organic soils. Reliably winter hardy to USDA Plant Hardiness Zone 5, especially when planted in protected locations with well-drained soils.
Popular cultivars include:
- ‘Munstead’
- ‘Hidcote’
- ‘Blue Cushion’
- ‘Royal Velvet’
These cultivars are compact, aromatic, and relatively hardy.
Lavandin (Lavandula × intermedia)
Lavandin is a hybrid between English lavender and spike lavender. It is less cold-hardy than English lavender but can survive in protected sites with excellent drainage. Winter hardy to USDA Plant Hardiness Zone 5, but only when placed in a protected location.
Common cultivars:
- ‘Grosso’
- ‘Provence’
- ‘Phenomenal’
‘Phenomenal’ has shown improved tolerance to both cold and humidity compared to older cultivars.
Lavender Types That Don't Overwinter in Iowa
Spanish lavender (Lavandula stoechas), spike lavender (Lavandula latifolia), and French lavender (Lavandula dentata) are not winter hardy in the state. Gardeners typically grow these as annuals or in containers that can be overwintered indoors.
Propagation
Stem cuttings provide the most reliable way to propagate lavender. Cuttings taken from non-flowering shoots, typically found on the side of the plant, root readily in well-drained media under moderate humidity.
Lavender seed germinates slowly and unevenly, often taking two to four weeks or longer. Cold stratification improves germination. To stratify, place seeds in a moist medium such as sand or peat and place in a refrigerator (40°F) for two to four weeks before sowing. Sow seeds on the surface of a well-drained seed-starting mix, maintain consistent moisture without saturation, and keep temperatures near 65 to 70°F. Seedlings grow slowly and require bright light to develop strong stems. Once established, transplant them into individual containers and harden them off before planting outdoors.
Seed-grown plants often vary in growth habit, size, and flower quality, so they may not match named cultivars. For uniform plants with known traits, propagation by cuttings remains the preferred approach.
Potential Problems
Apart from the unreliability of overwintering, lavender has relatively few pest issues when grown in suitable conditions. Most problems arise from excess moisture or poor air circulation.
Root rot is the most common issue and often results from poorly drained soils or overwatering. Fungal diseases may also develop under humid conditions, particularly in dense plantings.
Insect pests are typically minor. Aphids and spittlebugs may appear occasionally, but they rarely cause significant damage. Most infestations can be adequately controlled by spraying them off with a strong stream of water. Healthy plants growing in well-drained soils generally avoid serious pest problems.
Overwintering Lavender
Winter survival is the greatest challenge for growing lavender in Iowa and the Upper Midwest. Plants are most vulnerable when soils remain wet or when repeated freeze-thaw cycles occur.
Successful overwintering begins with proper site selection. Well-drained soils reduce the risk of root damage during winter. Elevated planting areas, such as raised beds, further improve survival. After the ground freezes, a light mulch such as straw or evergreen boughs can help protect plants without trapping excess moisture around the crown. Heavy mulches should be avoided because they can hold moisture and promote rot.
Choosing cold-hardy cultivars and planting in locations with good air and soil drainage increases the likelihood of winter survival.
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