Calendula is an extremely undemanding plant. In exchange for almost no work from you, it produces beautiful, vivid flowers. Besides being beautiful, the flowers have documented medicinal properties. Calendula is an extremely common ingredient in a wide range of skin care products due to its healing power.
Calendula is associated with sunshine because the flowers look like little suns. People often use the word marigold, or “Mary’s gold” in common names for calendula. It is also frequently used in devotional displays in India.
Why Grow Calendula?
There are a lot of great reasons to grow calendula.
- A key ingredient in many herbal salves
- Extremely easy to grow
- Resistant to many pests
- A nutritious, edible flower suitable for salads and decorating desserts
- An inexpensive substitute for saffron in recipes
- Somewhat frost tolerant
- Able to keep flowering for a very long growing season
- Attractive to butterflies, hummingbirds, bumblebees, and other nectar lovers
- A great cut flower, either for your own home or for sale
The active ingredient in calendula is oleanolic acid. Calendula based salves have been proven effective in treating conditions such as cuts, burns, and diaper rash. They also show promise for dermatitis related to cancer treatments, hemorrhoids, and other inflammatory skin conditions.
Eating calendula flowers gives you the benefits of Vitamin A and a little antioxidant boost.
One Word of Caution
Calendula has been identified as invasive in a few small regions of the US: mainly parts of California. Consult with your local cooperative extension before planting this plant. Planting invasive flowers can have unintended consequences on the ecosystems surrounding your home.
Some people, especially in Europe, refer to calendula as “marigolds.” The most commonly grown calendula species, Calendula officinalis, is also called the “pot marigold.” There is a separate genus of flowers that is also called “marigolds” that does not share calendula’s edible and medicinal properties. This is a bit confusing.
To make sure you have the right plant, look at the Latin name: Calendula officinalis.
Within the single species Calendula officinalis, there several cultivated varieties. Some have an especially high resin content, which makes them ideal for use in salves. Some are bred to be better suited as commercial cut flowers. These will typically live longer after being cut, and have a good stem for bouquets.
After distinctions based on use are made, you can choose a variety based on your preference for color or single vs. double blooms. They are all easy to grow.
When to Plant Calendula
Calendula grows quickly from seed. Most growers should start plants by direct sowing outdoors. This helps you to:
- Prevent transplant shock
- Avoid having leggy starts
- Save indoor space for other plants
If you are planting calendula outdoors, you can plant your seeds as soon as your soil is warm to the touch during the day.
If you have an extremely short growing season, you can start plants indoors to make the most of your precious frost-free days. I often start flowers a little earlier than my vegetables.
When I first started calendula indoors from seed, I realized that the early start was a mistake! I soon had huge plants, yet the ground outside was still frozen. If starting indoors, start calendula seeds no more than four weeks before your last frost date.
If you have a relatively long growing season, you can succession plant once or twice to ensure you have blooms all season. However, with regular deadheading I have found that individual plants can flower for a very long time. Succession planting is not necessary in areas with shorter growing seasons.
Calendula is not a heat tolerant plant, although it is hardy to dry conditions. Growers in desert regions such as the four corners should plant calendula towards the end of summer. It will produce beautiful fall flowers for you, and if you need to conserve water it will understand. It should be able to survive a chilly fall with light frosts.
I have not heard of people in places that are truly hot year round growing calendula.
Where to Plant Calendula
Calendula can grow in full sun or partial shade. I personally think the blazing orange and yellow flowers are prettier in full sun.
Calendula does very well in flower pots, window boxes, or any other container. It does not require a large amount of soil. Just make sure the container has adequate drainage holes to keep the soil from becoming swampy. It prefers drier conditions.
Calendula is called a “nutrient accumulator” in permaculture literature. This means it is good at “gathering” sparsely distributed nutrients from the soil, and concentrating them. This makes it an excellent addition to mulches and compost, and a good companion to most plants.
I have not found any plant families that are not recommended for planting with calendula.
With companion planting, there is always the theoretical and the practical. Plants may theoretically be good for each other, but in your personal garden may prove impractical.
I would not plant calendula with any vegetables that you would heavily fertilize. This will lead to enormous calendula plants that can completely take over the area. This is an especially big problem if it is paired with a slow growing or diminutive vegetable, that can be easily shaded out.
I learned about the above the hard way. I had always planted calendula in flower pots that had pretty crummy soil. They grew into compact little plants with big, showy flowers. When I took over a vegetable hoop house, I decided little calendula plant borders would be nice in some spots.
I soon had monstrous plants that were constantly spilling onto our walkways. I spent a lot of time cutting, tying, and ripping out plants. I considered completely pulling all the plants out, but I decided instead to supply all the flowers for a friend’s wedding.
Step by Step Guide to Growing Calendula
Growing Calendula from Seed
Calendula is extremely easy to grow from seed.
Calendula has large, crazy looking seeds. This makes them a great choice for planting with small children. The seeds are easy for little fingers to handle, and fun to look at.
To direct seed outdoors, sow seeds about every 2 inches in holes 1/4” deep. Thin plants when the foliage is touching.
To start in containers, sow two seeds per cell. Keep reasonably warm and moist. Starts tend to grow quickly. Be sure to provide even light to prevent them from growing leggy. If you must start the plants in a window, rotate the cells once or twice per day. Plant out as you would any other flower start.
Transplanting Calendula Starts
If you are in a pinch and must start with starts, look at the plants carefully. Make sure they are not tall and scraggly. If you can find starts that are small but healthy, these will do well.
If you can only find larger starts, make sure the grower took the time to pinch the starts back. You should not have one tall stem with just one flower. Instead, growth should already be slightly bushy.
Plant starts about 9 inches (25 cm) apart.
Pinching Calendula Back
Pinching flowers back is very important to get more blooms. If you do not practice any pinching, you will have a long scraggly stem with a single flower at the top. If you pinch back when they are small, each plant will have several stems. Each stem will have flowers. You can pinch these stems as well, depending on how bushy you want the plant to be.
To pinch back, simply look for the growing stem in the middle of the calendula plant. Pinch off the top of the stem flush with any lower growth of the plant. This will encourage other stems to grow.
Be careful not to pull upwards on the calendula stem when pinching. Calendula does not have a strong root system- it does not take much to accidentally dislodge the plant.
Calendula is a fairly drought-tolerant plant, but it does not like extreme heat. Try to water the plants during hot weather.
Calendula is susceptible to mold. This means you should avoid getting the soil overly wet. You should also water from below, either using a drip system or carefully inserting a watering can beneath the foliage. Wetting the foliage with overhead watering can promote mold.
Once the plants get their start, they should be able to compete with weeds on their own. Unless you have extremely pernicious weeds, you can probably let nature take its course.
Calendula does not need much fertilization. Add a little bit of compost to your soil before planting, and most plants should be fine.
If you have big, leafy plants without many flowers, this is an indication that you have too much nitrogen and not a lot of phosphorous. If you have plenty of flowers but your plants are small, the opposite is likely the case. This is not really a problem unless you are trying to grow the plants primarily for cut flowers.
Fertilizers are labeled according to their Nitrogen, Phosphorous, and Potassium content (N-P-K). The numbers will always be in the same order. For example, a typical bat guano, at 10-3-1 is 10% nitrogen, 3% phosphorous, and 1% potassium.
If you do add fertilizer to your calendula, just a sparing application will be more than enough.
Allowing Calendula to Self-Sow
Calendula is an annual, meaning of course that it dies in winter and does not return. However, it also quite commonly “self sows” if allowed. This means that your initial investment in seeds can be increased to multiple years of harvest.
To encourage calendula to self sow, allow a few flowers to remain on a plant until they fall off on their own. Do not turn the soil over. Just top dress with compost at the end of the growing season, and the beginning of the next one. Gently aerate in spring if the soil is hard and compacted. Otherwise, leave it be.
Allowing a plant to self sow will end its blooming season. Therefore, you should not do this with every one of your plants.
Removing dead flowers encourages the plant to keep making new flowers. If you don’t deadhead, your plant will stop making flowers and put energy into making seeds.
When flowers aren’t looking their best anymore, snip them off. Use clean, sharp scissors or pruners to reduce the risk of infection at the cut site. You can also cut the stem back to where it meets the other stems on the plant. This improves the general appearance of the plant.
You may notice whole plants looking ratty by the middle of a warm summer. You can encourage fresh new growth by liberally cutting back the plant. Cut down scraggly stems and blooms, but leave the plant’s base intact. It will soon recover and produce more stems and blooms.
For edible and medicinal use, harvest fully open flowers.
For cut flowers, harvest calendula when flowers are half open.
For cut flowers you plan to sell, make sure that your tools and storage containers are all extremely clean before use. Use extremely sharp tools. Cut flowers in the cool hours of the morning. The plant stems should feel firm to the touch when cut. Cut stems at an angle so they do not lie flat against the bottom of the container. Remove all foliage that will be under water.
Keep cut flowers in cool and dark conditions after harvest. You may choose to use cut flower plant foods or other products, depending on the scale of your cut flower operation.
Preserving Calendula Flowers
Calendula flowers can be dried and stored in airtight jars for future use. I put a liberal sprinkle of dried petals in rice, to make imitation saffron rice. It is not quite as delicious as true saffron, but it does have a very nice flavor. It also adds pretty color, and a little boost of vitamins and anti-oxidants.
To dry the flowers, you can either place them whole in a dehydrator or spread them on a screen. If using a screen, you can suspend the screen near a woodstove or keep it in a shady yet dry place such as under a tree. Too much sun will bleach the flowers.
Whichever method you use, make sure flowers are extremely dry before storing. Flowers should feel light, papery, and warm to the touch throughout. If in doubt, give them more time.
Some people remove the petals before drying. These are a little bit harder to handle than whole flowers. On the other hand, whole flowers take longer to dry.
I hope you have an opportunity to add calendula to your life. The vivid, cheerful blooms will give you a lot of pleasure, and you barely have to work at all to gain it.