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Everything You Need to Know About Marigold Flower Growth Expectations in Your Garden

Marigolds are generally compact plants with stunning blooms in various colors and offer lots of additional uses and benefits and symbolic value. Along with differences in foliage, flower color, and bloom shape, there are also vast differences in height depending on the type of Marigold and the specific cultivar. This guide will cover everything you need to know about how tall marigolds grow. 


How Tall Do Marigolds Grow? – Essential Tips

On average, Marigolds grow between 6″ and 24″ tall, depending on type and cultivar. French Marigolds are usually shorter than African Marigolds. Factors like growing conditions, fertilization, and planting can influence the potential height, but it is mainly impacted by chosen Marigold species and cultivars.


Marigold Basics

Marigold Basics

Suitable Growing Zones

As annuals, Marigolds can be grown in across USDA Zones 2-11 without trouble. They should be planted when the weather warms after the last frost in spring and will survive until the first frost of fall.

Once frost kills the foliage, they will need to be pulled from the garden. However, you can save the seeds from the flowers and plant them again the following season to ensure your Marigolds light up the garden year after year.

Best Exposures

Marigolds appreciate full sun and require at least 6-8 hours of direct light per day to flower successfully. Marigolds adore sunlight and grow rapidly, but they are not suitable for deep or partial shade as they will struggle to flower and may succumb to powdery mildew.

French Marigolds may benefit from some coverage in the intense afternoon sun in hotter regions. African Marigolds are better suited to these areas as they can handle the heat.

Bloom Time

Bloom Time

Marigold bloom time depends on the type of Marigold you’re planting and the specific cultivar. There are four types commonly in cultivation:

  • French Marigold: Tagetes patula
  • African Marigold: Tagetes erecta, also known as Aztec or American Marigold
  • Signet Marigold: Tagetes tenuifolia
  • Triploid Marigold: Tagetes patula x erecta, a hybrid cross between French and African types.

French and Signet Marigolds usually flower the earliest, while African Marigolds take slightly longer to mature. These flowers bloom throughout summer and into fall when conditions are right.

Soil

Marigolds are happiest in well-draining soil rich in nutrients with a slightly acidic to neutral pH. They are not majorly fussy and generally grow well in any soil type, except for heavy clay.

If the soil does not drain well enough, amend with compost and sand before planting to improve conditions or plant in containers.

Amendments & Fertilizer

In suitable soil, Marigolds can live without fertilizer. But generally, they will benefit from an extra boost of nutrients at planting or throughout the marigold growing season if they are not performing well.

In poor quality soil, add compost to improve organic matter prior to planting. If nutrient levels are low, you can also add a slow-release fertilizer at the same time or soon after planting to give the plants what they need to bloom well across the season.

Later on in the season, if they are not performing well, add a high phosphorus fertilizer to the soil to improve flowering.

Watering

After planting, Marigolds prefer evenly moist but not soggy soil to establish a robust root system. Once the foliage has filled out, reduce the watering to when the top layer of the soil starts to dry out. You may need to water more often in summer to prevent heat stress and maintain flowering.

Always water the soil directly, avoiding the foliage and flowers. This prevents the proliferation of disease and potential rotting in the dense flower heads.

For more, see our in-depth guide to watering marigolds.

Diseases and Pests

Diseases and pests are not common in Marigolds, but they are not impossible either. Bugs like spider mites and leaf miners can still attack these plants, despite their ability to control other pests like whiteflies. Remove with neem oil or insecticidal soap until all traces of the pests are gone.

Powdery mildew is one of the most common Marigold diseases, including root rot and leaf spot. Diseases are always better to prevent than control by avoiding overwatering, pruning dense growth, and spacing the plants correctly.

How Tall Do Marigolds Grow?

How Tall Do Marigolds Grow?

Generally, Marigolds are compact plants with dense foliage and stunning blooms that sit around the plant in a circular pattern. There is no set size as it varies widely by type, ranging from a short 6 inches to more than 2 feet in height.

Compact plants are often labeled dwarf Marigolds. These are great for edging or use in containers as their spread and height are contained, not overwhelming any pots they are planted in. Taller Marigolds are suitable for mixed flower beds or borders.

Height varies by type and cultivar, so ensure you check the label of your specific Marigold before planting.

Marigold Height Variance By Type

Marigold Height Variance By Type

French and Signet Marigolds are usually the smaller species, ranging in size from 6 inches tall to 12 inches tall. Their smaller size is complemented by the more delicate, smaller flowers of these species.

African Marigolds, on the other hand, can grow much taller. While they generally remain around 1-2 feet tall, they can grow even taller than that. Their flowers are also larger, with some reaching several inches in diameter.

These varieties give you an idea of the differences in size between the two:

French Marigolds

  • Hero: 10”
  • Boy O’ Boy: 6”
  • Aurora: 1’

African Marigolds

  • Safari: 1′
  • Jubilee: 2′
  • French Vanilla: 2′

Factors Contributing to the Height of Marigolds

Factors Contributing to the Height of Marigolds

Overcrowding

Marigolds need to be spaced correctly when planting. This ensures they do not compete for resources or limit airflow, encouraging the proliferation of pests and diseases.

Overcrowded Marigolds will experience stunted growth, impacting their overall height. They may also struggle to flower and will perform poorly overall.

Space your chosen Marigolds around the same size as their mature spread. This is generally 8″ for French Marigolds and 10″ for African Marigolds on average but differs by cultivar.

Growing Conditions

As with any plant, height is linked to growth and performance. If not given the right conditions and care, your Marigolds will not grow to their full potential.

Sunlight is the most critical consideration in care. These plants need a full day of direct sunlight to grow successfully. If planted in partial shade, they may begin to stretch toward the light source. Although this will technically make them taller, they will look untidy, diminished, and are unlikely to produce flowers.

Soil conditions, nutrient levels, and correct watering all contribute to overall health. Give the plants precisely what they need, and they will grow to their expected size.

It’s also worth cutting back marigolds at the end of the season in preparation for the upcoming year. 

Fertilizing

Fertilizing

When planted in poor quality soil, Marigolds may not grow to their full height as they do not have the right resources to do so. In these cases, fertilizing will kickstart growth again, allowing them to grow taller.

However, overfertilizing can have the opposite effect. Burning the roots and leaves overfertilizing will negatively impact growth rate and size until the soil is flushed. Only fertilize when absolutely necessary and according to packaging instructions for the best results.

Pests and Diseases

Stressed or vulnerable plants are more susceptible to pest and disease damage. The impacts differ by issue, but generally, these problems stunt growth and impact overall height.

For example, leaf miners feed on plant tissues, leaving their characteristic trails behind. This saps energy and resources from the plant, leaving them unable to grow taller. Things like powdery mildew impact photosynthesis when it comes to diseases, leading to slower or stunted growth.

Manage any pest or disease issues as soon as they are discovered, and your Marigolds should reach their full height in no time.

Wrap Up

With a wide range of heights available across each species, there is an ideal marigold for every use in the garden. They’re also great for growing in pots to enjoy on your balcony or patio throughout summer and work great as cut flowers for a bouquet or vase arrangement.

For more, see our essential guide to everything you need to know about how to grow Marigolds.


Author

Madison is a writer and editor with a Bachelor’s degree in History and Political Science. She writes and photographs for various online and print publications in the gardening sphere and is the author of the book The Next-Generation Gardener.

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