Guide to Biennial Plants: How to Grow Biennials in Your Garden

Biennials are plants that complete their full life cycle in two years. Biennials germinate during the autumn or spring months and produce roots, a stem, and rosette leaves in their first year before dormancy in the winter. The following year, biennials produce flowers, fruit, and seeds during their second growing season.

Unlike perennial and annual plants, true biennials are rare. Gardeners may choose to grow biennials as annual. Biennial flowers include:

1. 1. Angelica
2. 2. Black-eyed Susans
3. 3. Canterbury bells
4. 4. Forget-me-nots
5. 5. Foxglove
6. 6. Hollyhocks
7. 7. Stock
8. 8. Sweet William

Many common garden vegetables are actually biennial plants that flower and produce seeds in their second year. Biennial vegetables and herbs include:

1. 1. Brussels sprouts
2. 2. Dill
3. 3. Kale
4. 4. Carrots
5. 5. Celery
6. 6. Swiss chard
7. 7. Turnips

Growing biennials is a long and rewarding process. Below are tips to properly care for your budding biennials.

1. 1. Find your plant hardiness zone. The USDA maintains an online hardiness map, searchable by zip code, which divides the United States into 13 zones based on average annual minimum temperature. Find your zone and familiarize yourself with the biennial fruits, vegetables, flowers, and herbs that thrive in it.
2. 2. Water consistently. All garden plants need to be regular watering (in addition to the proper amount of sun) to grow. When the weather is cool in early spring, water biennials about once a week, increasing to two or even three times per week once the air temperature increases. You may not see much growth in the first season, but it is important to still water regularly.
3. 3. Compost and mulch your soil. The fungi, bacteria, and organic matter in compost enrich the soil with nutrients. This promotes strong immunity in your biennial plants and extends the life of your crops. Adding mulch to the top layer of your soil can also give your biennial vegetables a head start in growth.
4. 4. Use natural or organic pesticides. All vegetables are prone to pests like flea beetles and aphids. For insect pests, use an organic or noninvasive pesticide. A net or fence around the perimeter of your garden will help keep out larger animals. You can also pair your biennials with companion plants that naturally repel pests.
5. 5. Weed often. Weed your garden to do this in the morning when the soil is damp and you can pull the weeds easily. This ensures that your biennials don’t get shaded out by fast-growing weeds.
6. 6. Prune your biennials. Throughout the year, remove dead or dying foliage from your garden. This will improve the look of your garden while also promoting healthy, new growth in the second year. When your biennial plants bloom, remove spent flowers by deadheading—pinching or cutting off dead blooms—to encourage continued growth.
7. 7. Start a diary. Keep a garden journal to track your vegetables’ progress. Note when and where you planted your vegetables, whether pests are interfering, and any pertinent details about the development and health of your crops.

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