The geranium is one of the most recognizable garden flowers. They are a popular choice amongst gardeners, filling containers, beds, and hanging baskets with attractive foliage and floral color. An easy to care for plant, growing geranium plants is a rewarding process. Here is everything you need to know.
Varieties of Geranium
Common garden or annual geranium plants are actually derived from the Pelargonium genus. Originating in South Africa they can be grown in the United States as an annual plant. In the warmest USDA zones they will grow as perennial plants. In cooler climates geranium plants can be overwintered indoors before being replanted out in the spring. Finally, they can also be grown as a houseplant.
A truly versatile plant there are over 300 species available ranging in color, shape, scent, size and foliage.
Bright and colorful, geranium plants are a popular way to fill spaces in beds and borders. However they are attractive plants in their own right, groups of these flowers can provide a particularly eye catching display.
The four most popular varieties are:
Ivy Geraniums– produce abundantly cascading mounds of flowers which sit on shiny, ivy-like foliage. The flowers can be single, semi-double or double blooms, and will display from early in the spring until the first frost of the year. Popular cultivars include Contessa, Summer Showers and White Mesh.
Regal Geraniums– produce large, multicolored blooms. Also known as Marsha Washingtons they are a delicate variety but will thrive with the proper care. Best suited to gardens in cooler climates, they will not flower in hot temperatures. Cultivars include Coral Sea, Ace High and Blue Orchid.
Scented Geraniums– are not a heavy flowering variety. They make up for this with stunningly scented leaves. The foliage also has an interesting velvet-like texture. The name of the cultivar often reveals the scent of the plant, popular cultivars include Chocolate Mint, Lemon Balm and Ginger.
Zonal Geraniums– the final variety is the classic version of the plant. Easy to grow and tolerant of heat and drought conditions they produce single and double flowers in shades or orange, yellow, purple, red, pink and white. Popular cultivars include Rocky Mountain, Tango and Classic.
The endless variety of geranium plants on offer means that you won’t be short of choice. Growing plants of the same variety and color can create a colorful swathe in a flowerbed. Alternatively mixing things up by growing a range of plants can provide contrast in the garden.
The Authentic Variety
If you want to cultivate authentic, hardy geranium plants you will need to select members of the Geraniaceae family. Again, you will have plenty of choice, especially if you look at cultivars from the Geranium macrorrhizum genus or the hybrids oxonianum and cantabrigiense.
The majority of cultivars are perennial in USDA zones 3 to 8. Most also have strong rhizomes, this means that once established they will spread easily through the garden. This makes them an excellent choice for providing ground cover.
How to Grow Geranium Plants From Seed
While they can be purchased as young plants ready for planting or grown from cuttings, you can also grow from seed.
Seeds are easily available from garden centres and can offer a wider range of choice than if you purchase going plants.
If you are growing from seed you will need to sow early, undercover. Depending on the variety, you will be enjoying flowers within 16 weeks of germination.
Fill a tray or container with fresh potting soil. The soil should be evenly moist. Seed starting mix can also be used. Cover the seeds thinly.
Cover the trays with a clear plastic bag and place in a light location, a South facing windowsill is ideal. Seeds germinate best when the temperature averages 75𝇈F. Regularly check the trays, the soil should not be allowed to dry out.
Scatter seeds as thinly as possible. If seeds do germinate in clumps, weaker seedlings can be picked out later on.
Depending on the conditions germination can take between 3 days and 4 weeks. As soon as the first green shoots emerge, remove the cover. Keep the soil moist.
The growing seedlings should sit in a light place that averages 70 °F in the day. At night the temperature shouldn’t fall below 60 °F.
Despite being small you can now begin fertilizing your seedlings. Apply a half strength, or diluted, liquid fertilizer once a week.
When the seedlings have three sets of true leaves they can be transplanted into 3-4 inch pots.
Allow the seedlings to grow on until the last local frost date has passed. You can then begin hardening off seedlings. After a week to ten days of hardening off or accounting the young plants can be transplanted to their final location.
How to Plant Geraniums
Indoor plants require lots of light to encourage flowering. They will tolerate moderate light conditions but may not bloom as profusely. The temperature should average 65-70 °F during the day. At night it shouldn’t drop below 55 °F.
if you are planting in containers ensure that the container is clean and has drainage holes in the bottom. Adding a layer of crocks or pebbles to the bottom of the container will help to improve drainage. Fill the container with fresh, well-draining soil.
If you are planting into a bed or border, before planting work the soil well. This will break up clumps of earth and improve drainage. As you dig over the soil work in a quantity of organic matter such as homemade compost. This will enrich the soil and help to give the geranium plants an extra boost. Heavy soil should be amended by working in compost or peat. This will help to loosen it.
Geranium flowers look particularly effective when planted in groups. Be sure to space the plants correctly, this will help air to circulate and prevent diseases from developing.
If you are planting outside, your chosen site should receive 6 to 8 hours of full sunlight. Geranium plants will grow In all USDA zones. In particularly warm areas they will appreciate a little shade from the hot afternoon sun.
While you should wait until after the last frost before planting out, don’t wait too long. Exposing geranium plants to cool nighttime temperatures encourages flower buds to form.
The soil should be 60 °F before planting.
To plant, dig a hole large enough to comfortably hold the root ball. Position the plant in the hole and backroom with soik, being careful not to compact the soil. Mulch around the base of the plant, this will help the soil to retain moisture. Space plants 8 to 12 inches apart depending on the variety.
Caring for Geranium Plants
Once planted these are easy to care for garden flower.
Water thoroughly as soon as the soil feels dry. plants growing outside will need to be watered weekly. Plants growing indoors or in containers will require more frequent watering, possibly as much as once a day.
If you are growing in containers, water until the water begins to drop from the bottom of the container.
When watering, aim to water only the soil. Damp leaves can be a breeding ground for disease.
These plants don’t require lots of fertilization. Over fertilizing can lead to too much foliage being produced at the expense of flowers. Apply a 20-20-20 fertilizer every three weeks during the growing season. Mix 2 tablespoons of a water soluble feed into a gallon of water. This solution can be applied every three weeks during the growing season.
For houseplants apply a general purpose 5-10-5 or water soluble houseplants fertilizer every four to six weeks. Organic alternatives or homemade liquid fertilizer can also be used. Adding a layer of mulch or organic matter every 6 weeks during the growing season will also help to encourage healthy growth.
Regularly watering and feeding your plants will encourage plants to grow and flower. Deadheading, or removing spent flowers, encourages more flowers to emerge. This enables you to enjoy a continuous floral display throughout the summer.
Remove spent blooms. This will help to keep the plants healthy. It will also encourage more flowers to emerge.
Houseplants can become leggy or thin. Regularly pinching out the growing points will help to prevent this by encouraging branching.
Geranium plants growing in containers will require reporting every few years. This will prevent them from becoming overgrown and potbound. Plants working between watering is a sure sign that they require repotting.
Propagation from Cuttings
Geranium cuttings easily root. This means that you can propagate new plants with little trouble.
To divide plants dig them up and carefully cut the roots in half. Use a clean sharp knife. This will help to prevent accidental damage to the plants.
Propagating in the fall from cuttings is a reliable way of saving outdoor plants. You can also dig up plants and take them undercover during the winter. Putting plants to bed in this way can form part of your garden’s fall transition.
To overwinter plants growing in the soil gently dig up each plant. Pot in 8 inch containers filled with a light potting soil. These can then be replanted outside in the spring once the last frost date has passed.
Geraniums growing in containers can be moved inside as the temperatures begin to fall.
If planted and cared for correctly these plants are largely problem free. Most pests avoid geranium plants.
Fungal diseases such as botrytis can strike. Control infections with an application of a commercial fungicides. Alternatively an organic control can be applied.
Finally overwatering can cause plants to develop issues such as root rot.
With the correct care your plants will be largely healthy and problem free. In return, they will reward your efforts with ample amounts of lush green foliage and scores of colorful blooms.
Failure to Flower
A popular houseplant, geranium are well suited to growing indoors. However if they constantly sit in a warm environment they can fail to flower. Removing the plants to a cooler location for a couple of weeks will encourage buds to set.
Geranium plants repel most pests and insects. This makes them a great companion plant. Traditionally they grow alongside roses. They also look great mixed in with other bedding plants such as impatiens and spring flowering bulbs like tulips and daffodils.
They are also commonly planted in vegetable gardens. Planting them alongside vegetables such as cabbage, corn or vining fruit like grapes helps to deter pests from plants that would otherwise be magnets for destructive pests.
A classic combination, growing these flowers alongside roses can create a stunningly effective display. Growing this combination also helps to protect roses from some common pests.
Geraniums are a reliable addition to any garden. A useful companion plant they are particularly useful controlling in the gap between spring flowers facing and summer flowers blooming.