Large Herbs as Window Box Thrillers

When planting my front door container garden this year, I was wondering what to plant for the thriller, and decided I wanted to use a large, interesting herb as a focal point.

By now, we have all heard about thrillers, fillers and spillers in container gardening and window boxes.One way to make beautiful container gardens and window boxes is to mix up the variety of plant size.

• A tall, centerpiece plant, is called a thriller.
• Spillers are those plants that grow over the sides of the flower pot.
• A filler does exactly that – it fills in the spaces between the thriller and the spiller. The filler usually is the main plant in the container garden.

Or, as my art teacher taught me, good art usually has a “papa bear,” “mama bear,” and “baby bear.” A little papa bear – the thriller to attract attention, a little baby bear to add surprising interest and mostly the mama bear, who does all the work. Hmmm, I don’t think I’ll comment on that!

When I was planting my self-watering container garden for spring, I was trying to figure out how to apply this to the multiple pots the planter crate holds. I don’t know about you, but since I am a thrifty gardener, I just hate to buy plants, especially plants that don’t have a lot of purpose, or cannot live through the winter. I do buy a few flowers, because, well, flowers! But, it is really tough to for me to buy thrillers and spillers!

For spillers, I could plant some vinca, which I have in plenty around the garden, or other trailing vines – maybe strawberries for fun, or some ivy from the wall. A common plant used for the spiller is the sweet potato vine which has lovely light green leaves. For thrillers, though, most online articles say to use an ornamental grass.

I really didn’t want to buy an ornamental grass, so looked around for other tall, interesting plants. There were many ferns growing near my house, so I tried those in the container garden first. The ferns didn’t transplant into the flower pot very well, and ended up looking pretty bedraggled. There are also lots and lots of irises and day lilies around the garden which have lovely grass-like foliage after the blooms are done.

But, I think I would rather find a large growing herb, so I have a lovely scent and a useful plant right outside the front door. And, so began my research.

Here I share what I have found out for attractive, large herbs that will grow in a container garden or flower pot.

1. Flat Leaf Parsley for Container Garden

Some flat leaf parsley, such as Giant of Italy, can grow up to about 20 inches tall. This type of parsley grows to be a large, bushy plant, with sturdy stems and large dark green, flat leaves. The leaves are soft and easy to chop

• Size: This herb can grow up to 24 inches
• Zone: 6 – ideal for container gardening and bringing indoors in the winter in colder climates
• Water: Keep well watered
• Sun: Partly sunny or full sun
• Soil: Moist, rich potting mix
• Pests: Slugs, fungus

Parsley can grow well in a pot, with monthly fertilization. The soil should be kept moist or watered about once per week. To keep the foliage lush, trim regularly, and trim off any flowers before they bloom.

Parsley is a great choice for a kitchen garden or herb garden, because you can use it in almost every recipe!

2. Rosemary for Container Gardens

Rosemary is a large, woody stemmed herb with thin pointy leaves that can grow to 3 feet and even larger in warm climates.

• Size: Different varieties of rosemary can grow to different heights, ranging from 12 inches to up to 4 feet (Sissinghurst Blue) or even 6 feet (Miss Jessopp’s Upright)
• Zone: 8
• Water: Let dry between watering and add fertilizer when flowering
• Sun: Sunny
• Soil: Potting soil and compost mix
• Pests: rosemary beetle

Rosemary grows well in pots, and can be brought indoors during the winter in colder climates. This herb  is an evergreen, so you can pick fresh leaves all year long. They are also tasty and fragrant dried. Rosemary would add lovely deep green color, texture and scent to a container garden.

3. Sage for Container gardens

Sage grows in a bush like shape. It has lovely, light green, pointed leaves that have intense flavor.

• Size: Depending on the variety, sage can grow from 12 inches up to 4 feet (Silver Sage)
• Zone: 4 to 11, depending on the variety
• Water: Let the soil dry a little between waterings and give fertilizer only during flowering
• Sun: Medium to full sun
• Soil: Well-drained, sandy, loamy soil or a potting soil and compost mix
• Pests: Very few, red spider mite, Leaf hopper
• Propagation:  Best to grow from cuttings.

Sage will grow will in container gardens. Sage is an evergreen plant and can be used any time of year. In colder climates, choose a cold hardy variety and protect over the winter. It is better fresh than dried.

4. Lemon Balm for Container Gardens

• Size: 2 feet tall
• Zone: 4 – 9
• Water: Keep moist, fertilize regularly
• Sun: Full to partial sun
• Soil: Well-drained soil – mixture of well drained potting soil and compost
• Pests: Mint rust

Lemon balm is a member of the mint family and grows quickly. It has flat, lightly textured leaves that when crushed, smell of lemon and slightly mint. The plant can over take a garden, but grows well in containers and flower pots.  To encourage growth, trim during the summer.

5. Lavender for Container Gardens

• Size: Lavender is a large plant that can grow from 18 inches up to 3 feet, depending on the variety
• Zone: 5-9 depending on variety
• Water: Allow to dry in the winter, and water more during growing season. Fertilize while the plant is flowering.
• Sun: Full sun
• Soil: Potting soil and compost mix
• Pests: Rosemary beetle, gray mold, fungus

Lavender is related to rosemary, and also grows with woody stems and thin green needle leaves. This herb can grow well outdoors in warmer zones. However, in colder areas, the plant grows well as a container plant, and can be brought in doors during the winter. Trim lavender in the spring to encourage growth, and trim again after flowering. The flower can be dried and used.

6. Basil for Container Gardens

• Size: 9 – 18 inches depending on the variety
• Zone: Annual in all zones
• Water: Water well in midday, do not over water
• Sun: full sun
• Soil: Well-drained soil, mixture of potting soil and compost
• Pests: Greenfly and whitefly, fungus

Basil has large, deep green or purple leaves and has a very strong scent and flavor. This herb grows well in a container and can be brought in during the winter months. It is easy to cultivate with cuttings from an existing plant. Keep trimmed to encourage bushy growth.

Basil grows well in a container garden and is often used to repel flies. Purple basil would work well as a thriller or centerpiece in a container garden.

7. Hyssop for Container Gardens

• Size: 12 inches to 36 inches depending on variety.
• Zone: 3
• Water: Let dry between watering. Fertilize during flowering
• Sun: Full sun
• Soil: Potting soil and compost mixture
• Pests: Very few

Hyssop is a large herb that often grows tall, with narrow, pointed leaves. With its pink or blue flowers, it would make a terrific thriller for any container garden. Hyssop grows well in colder climates, but should be protected if left in the garden during winter months. Hyssop is an herb that also grows well in garden flower pots and adds a lovely scent to your window or patio garden during the summer.

8. Comfrey for Container Gardens

• Size: Comfrey can grow very large, from 10 inches to 3 feet, depending on variety
• Zone: 5
• Water: Keep well watered
• Sun: Full or partly sunny
• Soil: Soil and compost mixture
• Pests: Rust and powdery mildew

Comfrey can be grown in a large flower pot for outdoor use. It does not grow well indoors, but can overwinter in the garden.

9. Chives for Container Gardens

• Size:  8 to 16 inches, depending on the variety
• Zone: 3
• Water: Keep well watered and fertilize occasionally
• Sun: Full sun to partly sunny
• Soil: Mix of potting soil and compost
• Pests: Greenfly, Mildew, rust

Chives grows in long thin, bright green stems with purple or white ball shaped flowers. This herb has an onion smell and taste. Chives grows well in flower pots, and can be brought inside during the winter, but can also overwinter in the garden.

10. Sorrel for Container Gardens

• Size: 6 inches to 2 feet, depending on variety
• Zone: 3
• Water: Water well, and fertilize regularly during growing season
• Sun: Full sun to partial shade
• Soil: Mix of potting soil and compost. Likes acidic soil.
• Pests: Wood pigeons, slugs

Sorrel is broad-leafed, hardy perennial. It has a sour flavor and is a wonderful surprise in a salad. Sorrel should be used with care and in low amounts.

Best Thriller Herb for my Container Garden

So, of these 10 herbs that grow well in container gardens, which did I choose? I had it narrowed down to parsley, basil or thyme, mostly for the combination of size, usefulness in cooking and the wonderful scents. I found a wonderful, large thyme at my neighborhood garden center. So, for this year, the thyme wins!

But, now that I have this list, I will try something new for next year. Enjoy!