Big Blooms, Easy Care: How to Grow Annual Rose Mallow From Seed

Rose mallow, also called annual mallow, is a fast-growing, old-fashioned flower that brings bold color and soft, romantic charm to the garden. Known for its large, hibiscus-like blooms and easygoing nature, Lavatera trimestris is a favorite in cottage gardens, pollinator plantings, and cut flower beds. When grown from seed, it quickly fills space and flowers generously throughout summer.

Annual mallow is easy to grow from seed and performs best when directly sown outdoors. It has a strong taproot and prefers not to be transplanted once established. However, we have successfully started seeds indoors and transplanted seedlings when the temperature warmed up.

Sow seeds outdoors after the danger of frost has passed and soil temperatures have warmed. In cooler climates, seeds can be started indoors 6 to 8 weeks early and transplanted carefully while young. One tip is to plant seeds in pots that are large enough to accommodate the roots. When transplanting, be careful not to disturb the roots. Harden off seedlings before transplanting.

Plants grow quickly and will begin blooming in early to mid-summer, continuing until frost.

Although annual mallow belongs to the mallow family (which includes edible plants like okra and marshmallow), Lavatera trimestris is grown strictly as an ornamental flower and is not considered edible.

• Plant seeds ½” deep
• Keep the soil moist for seeds to germinate
• Seeds germinate in 7-20 days
• Soil temperature 60º-70ºF

Annual mallow is a low-maintenance plant that thrives in full sun and average garden conditions. Its upright growth habit makes it ideal for the middle or back of flower beds. Rose mallow plants do get large and produce lots of branches, so give them enough space to shine. Plan on spacing plants 18-24” apart. 

Rose mallow prefers full sun. Having enough sunlight will result in stronger stems and more flowers.

Your average garden soil will be fine for growing rose mallow. Make sure that it drains well, as waterlogged soil can lead to root rot.

Annual mallow doesn’t need extra fertilizer. We supplement our soil with compost before planting and use compost or a balanced, slow-release fertilizer later in the season. Too much fertilizer can result in excessive leaf growth.

Deadheading annual mallow is helpful but not required. Plants will continue to bloom on their own, especially early in the season, but removing spent flowers can encourage additional blooms and keep plants looking tidy.

Snip faded flowers just above a leaf node, or remove entire flower stems once most of the blooms on that stem have finished. Light pruning can also encourage bushier growth.

If you prefer a more natural or cottage-style garden, you can skip deadheading and allow plants to form seed pods. This may result in some self-sowing, but flowering may slow later in the season.

Annual rose mallow is usually free from pests and diseases, but it can have:

Root rot

Leaf spots and rust

Japanese beetles

No. Lavatera trimestris is grown as an ornamental flower, not as an edible or medicinal plant. While it belongs to the mallow family, it is not intended for consumption.

No. Marshmallow (Althaea officinalis) is a medicinal perennial grown for its roots, while annual mallow is a fast-growing flowering plant.

No. Annual mallow completes its life cycle in one growing season, though it may self-sow in mild climates.

Yes. The open flowers attract bees and other beneficial insects.

• Annual mallow belongs to the mallow family (Malvaceae), which also includes hibiscus, hollyhock, okra, and marshmallow.

• Despite its family ties to edible plants, annual mallow is grown purely for its ornamental value.

• The large, papery flowers often close at night and reopen with the morning sun.

• Annual mallow has been a staple in cottage gardens for centuries due to its easy growth and romantic appearance.

We love the beautiful colors of the Annual mallow (Lavatera trimestris) in the garden. It has such a classic cottage-garden look. The large, bright flowers attract hummingbirds and pollinators. Grown from seed, it establishes quickly and flowers reliably throughout summer, making it an excellent choice for gardeners who want fast results and low maintenance.

Grab a packet of heirloom seeds and add this low-maintenance flower to your garden.