For a novice gardener, Dahlia indoor maintenance might become challenging. Dahlias shouldn’t be kept indoors year-round because they require a certain atmosphere to flourish. It is better to begin growing them indoors and then transplant them outside after they have reached maturity.
If you intend to keep your dahlia indoors all year long, try to replicate the circumstances it would encounter outside. Learn how to control the temperature, humidity levels, watering requirements, soil demands, and all other requirements for a Dahlia to flourish indoors. You may find all the information you need to grow your dahlia to its best potential in this page.
My dahlias may I put outside?
Dahlias want a protected location with plenty of sunlight.
The best border is one that faces south or west. When it comes to soil, dahlias are not picky. Grow in any fertile, moist, but well-drained soil for the greatest results. Add some organic matter to the soil, such as well-rotted manure. Add some grit to the planting hole if you’re growing on dense clay. Use a high-quality, peat-free multipurpose compost if you’re growing dahlias in pots.
Growing dahlias from tubers
Dahlia tubers can be purchased starting in February. The majority of garden centers provide a decent assortment, but for the best choices, shop online.
You can place all of your tubers in a sizable shallow tray in early April and lightly cover it with compost in preparation for potting up later. Alternately, plant each tuber separately in a sizable plastic container filled with potting compost that serves many purposes. Place the tuber in the proper orientation—the top is the old stem or a new shoot—so that it lies just below the soil’s surface. Fill the container up to the top and let any extra water drip out.
Keep the compost moist and the tubers in a bright, frost-free area, such as a greenhouse, cold frame, porch, or windowsill. After planting, new shoots should begin to develop in about five weeks. By the time the frosts have passed in May, they will have developed into bushy plants.
In our No Fuss video instruction, Alan Titchmarsh demonstrates how to plant dahlia tubers.
Are dahlias happy in pots?
Dahlias thrive in containers, but you must be very careful not to constantly allow them dry out. During the growing season, they will also require routine fertilization, and many of them will need to be staked to prevent them from toppling over. Additionally, it’s a good idea to plant the taller types in hefty pots to prevent them from toppling over in strong winds.
Dahlia tubers are available for purchase online, at nurseries, and in select big-box stores. Dahlias that are already started in containers are also sold by many nurseries. Dahlias come in a wide range of plant and bloom sizes. The “dinner plate” dahlia is the flower to seek for if you want huge blooms. Look for miniatures or “low growing” dahlias if you want shorter plants.
Do dahlias like shade or the sun?
The biggest size offered is grade #1 dahlia clumps, which we sell. In these images, a sizable clump of grade #1 tubers on the right and a smaller clump of grade #3 tubers on the left are contrasted. It takes less time to establish a big plant with plenty of flowers when you have a larger clump since you have more eyes (or growth points) to start the season with.
Plan for Success
Dahlias are quite simple to grow. Here are some pointers to assist you achieve the greatest outcomes.
Dahlias enjoy the sun and require a minimum of six hours of direct sunlight each day. Dahlias should be planted in the most sunny area possible since the more sunlight they receive, the better their bloom.
Despite only being winter hardy in zones 8–11, dahlias can be grown as annuals in zones 3–7. Plant the tubers in the spring, and by mid- to late-summer the plants will be in blossom. You are unsure of your hardiness zone. The USDA Hardiness Zone Map can be found here.
Dahlias thrive best in loose, fertile, well-drained soil, as do the majority of plants. When planting, add compost and an all-purpose fertilizer to your soil to improve its quality. Dahlias should not be grown in regions with wet or compacted soil.
When to Plant: After all threat of frost has passed, dahlia tubers should be planted in the spring. Dahlia tubers can be started inside or in a greenhouse four to six weeks prior to the final day of frost if you live in a cold area and want your plants to bloom as soon as possible. Plant one cluster of tubers in each pot after adding growing mix to 1- or 2-gallon containers. When the weather is warm and settled outside, move the pots into a warm, sunny location before planting them in the garden. Dahlia clumps that have just been planted should get very little water until they have sprouted and are actively growing.
Where to Plant Dahlias
Dahlias bloom from late summer through the fall and reach their peak at the end of the growing season, just when most other plants are beginning to lose their color. Make sure you are aware of the final height of each kind before you plant dahlias in your garden. Tallest dahlias should be towards the back, followed by medium-sized dahlias and border dahlias.
Decks, patios, and entryways are perfect places to display gorgeous dahlia arrangements to welcome visitors. Border dahlias are perfect for edging walks and pots. The little, bushy plants are only 18 to 24 inches tall, and from midsummer till winter, they are covered in blooms.
Dahlias are not just for decoration; they can also be used as screening or along fences. To increase seclusion, full-size cultivars can be planted along a property line. They can be placed in the garden to block an unwelcome view or planted in pots to enclose a spot.
Dahlias want the same growing conditions as vegetables: rich, well-drained soil with constant moisture and lots of sun. Dahlias should be planted at the same time as peppers and tomatoes. You can bring in an armful of fresh flowers for your table when gathering your dinner.
Dahlias make wonderful cut flowers, and just a few plants will provide you with months of blooming. Planting a variety of flower varieties can give your bouquets a polished appearance.
How to Plant Dahlias
1. In well-drained soil, dig a hole that is 4-6 feet deep.
2. Position the tubers so that the stem is pointing up in the hole. The plant’s crown, where the tubers join the stem, needs to be between one and two inches deep.
3. If the soil is really dry, merely replace the dirt and water. In 2-4 weeks, sprouts will start to appear.
watering
A moist soil is preferred by dahlias. When there is a drought, give them a substantial flood, not a light mist, once a week. During a drought, water your dahlias repeatedly each day if they are in pots. These plants are thirsty.
staking
Every dahlia plant needs to be grown next to a stake. Be sure to keep tying the dahlias in every few weeks. If they are not firmly anchored, dahlias can easily break off at the base in wind or rain once they start to grow.
deadheading
Dahlias require routine deadheading, which will encourage flowering, if you don’t pick every flower for the house. Follow the blossom stem downward and cut above the first set of leaves you come across to deadhead.
propagating
Basal cuttings make it simple to propagate dahlias. Pick strong, vigorous shoots that are around 7.5 cm (3 in) long once the tuber has begun sprouting in the spring. Use a clean, sharp knife to cut them out, along with a small piece of the parent tuber. Pinch out the tip and remove everything but the top pair of leaves.
Prepare a 1-liter pot with a compost and grit mixture (3 parts compost to 1 part grit). Each cutting should be placed near the pot’s edge, with the leaves spaced so that they do not touch and slightly over the compost’s surface. The compost will sink with water from above. Place the plant next in a warm location or a heated propagator that is well-lit but not in direct sunshine. Make a pot label.
The cuttings will have developed roots in approximately 3 to 4 weeks. Carefully plant each cutting into a 7.5 cm (3 in) pot so that it may continue to grow before being planted outside when the risk of frost has passed. The plants developed from cuttings will flower later that summer and produce tubers with consistent feeding and watering.
overwintering
Our winters in the south of England have recently been so mild that dahlias planted in the ground and covered with a thick layer of mulch to shield them from the frost have recovered without issue, growing larger and blooming much earlier than other plants put in pots. If you choose this low-maintenance approach, you run the danger of losing your plants if we experience a harsh winter.
If you choose this course of action, dahlias can be left in place and protected with a thick mulch that you can remove in the spring after the worst of the winter’s frosts have passed.
Wait for the first autumnal frosts to turn the dahlias black before cutting them to within 10cm (4in) of the ground. Afterward, place labels where the crown is visible. It’s easy to forget which plant is where, so make sure each dahlia is labeled. Then cover each with a mound (a full bucket) of mulch. It’s like giving them a duvet for the winter if you bury them deeply.
The second method involves removing the dahlias from the ground and storing them indoors. If you’re growing dahlias in a mixed border, you should use this lifting technique since dahlias left in mixed beds may be obscured by spring and summer growth.
Dig up your plants in the autumn after the tops have frozen to ensure their survival for the following year. Before doing so, trim them to 15 cm (6 in). Scoop off the loose soil between the tubers with a little piece of wood after knocking off the excess soil, but leave just enough to keep the tubers in place.
Avoid washing the tubers under the faucet; at this time of year, getting water on a tuber can be disastrous. Place the tubers in a crate upside down and let them air dry for a few weeks.
Then store them in shallow trays or a storage container, enclosing the tubers in dry sand, vermiculite, or compost, or you can wrap them in newspaper. As a result, the tubers don’t dry out.
They should be kept in a cellar, attic, or shed that is cool and away from frost. Throughout the winter, check tubers frequently for rotting.
Dahlias can be grown inside.
One of the most vividly colored commonly available flowers is the dahlia (Dahlia hortensis). Depending on the cultivar, their hardiness varies slightly, although many varieties are hardy in U.S. Department of Agriculture plant hardiness zones 8a through 11a. Dahlias can be started indoors so that they can be transplanted and grown outside as soon as feasible. They can also be grown indoors in a sunny area while being kept in containers.
Do I need to start my dahlias inside?
For two reasons, dahlia growers might choose to start their dahlias indoors: to give them a head start before planting them outside and to boost stock by taking cuttings. Both require a location indoors, but cuttings require more effort (see course on Cuttings for details.).
Dahlias reappear each year, right?
Dahlias produced a colorful display through late summer and autumn, but it ends as soon as the first frosts appear. Dahlias can’t withstand frost, so as the temperature drops, the leaves and remaining blossoms crumple to the ground. But not everything is lost. If you give the underground tubers a little tender loving care, they won’t be harmed and will be able to perform again year after year.
Dahlia tubers are sometimes extracted, stored over the winter, and then replanted in the spring. Others in drier climates simply leave them where they are. What is the greatest way to guarantee a repeat performance the next year?
Basically, they typically survive the winter undamaged if your soil is well drained and frost does not penetrate too deeply. You can aid by mulching the area once the faded vegetation has been chopped back to the ground level with a thick layer of leaf mould, decomposed bark, or bracken. Dahlias are less likely to survive in the ground in damp conditions, thick clay soils, and in cold climates; therefore, it is usually advisable to lift them and store them in a frost-free location until the following spring.
Trim the stems to a few centimeters above ground if you choose to dig them up and store them. With a fork, delicately lift the tubers, being careful not to scratch them.
As much dirt as you can remove, ideally without washing them. However, if the soil is sticky, careful hosepipe washing may be required.
Then, if possible outside or in a well-ventilated shed or garage, let them dry for a few hours. Turn the tubers upside down so that the stem remnants are facing down when they are relatively dry, and then spread them out on dry newspaper so they can be left undisturbed until all of the extra moisture and sap has drained away. A place with no frost is necessary, as well as good ventilation. Conditions below freezing will always kill them.
Dahlia tubers were traditionally sprinkled with yellow sulfur to stave off fungus invasion. Many people use this on dahlia tubers as a prophylactic strategy even though it is advised as a plant nutrient and soil acidifier.
Some others simply spread the tubers in trays covered with fresh newspaper. Others spread the tubers out on wooden trays or even shallow cardboard boxes after loosely wrapping each one in a sheet of newspaper. Then, they must be kept in a dry, frost-free location with excellent air flow. Regularly inspect them and get rid of those that appear to be rotting because it will spread to the others.
Dahlia tubers can be planted directly into the ground where they will bloom in the middle of April. Avoid planting too early to prevent frost damage to the developing shoots.
As an alternative, you may start them in pots indoors and then plant them outside once they have grown.
While wind can harm their fleshy stems, dahlias prefer refuge from it and thrive best in an open, sunny location. Although they like plenty of organic materials around them, they prefer well-drained soil. The greatest results are ensured by a slow release fertilizer used early in the growing season; Vitax Q4 is perfect.