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How to Grow Dahlia

Perennial

Dahlias are easy to grow, tender perennials. This attractive, and very popular  flowering plant is grown as an annual in colder areas.  Native to Mexico, these plants will produce flowers the first year from summer through fall.

The Dahlia family comprises a large variety of plants with varying colors and sizes. Dahlias include dwarfs that are only 18 inches tall, to seven foot  tall varieties. The smallest flowers are just button sized, while the largest blooms are the size of dinner plates. Not surprisingly, these big varieties are called "Dinner Plate Dahlias". Flowers include single bloom and double bloom. Brilliant blooms include orange, salmon, bronze, apricot, yellow, crimson, scarlet and lavender.

Dahlias look great planted in groups, and make excellent bedding plants. The flowers are long lasting. They are also grown in containers, especially smaller varieties.  

They make excellent cut flowers.

Plant Propagation:

Smaller varieties of Dahlia are commonly grown from seed. For the earliest blooms, we recommend an indoor start six to eight weeks before the last frost in your area. Plant Dahlia seeds in pots, allowing ample room for root growth. This will make transplanting easier.

Larger varieties of Dahlias are propagated by separation of their tubular roots. This can be very useful, as you are assured of the  flower color to be produced by the new plant. Dig a hole 6-10 inches deep. Mix in plenty of compost and manure. Bury Dahlia roots with the crowns 3" below the surface of the soil.

Propagation by cuttings is also possible.

How to Grow Dahlia Plants:

Grow Dahlia plants in full sun to partial shade. They prefer a rich, well draining garden soil. Add plenty of compost and manure at planting time. Fertilizer should be applied regularly all season. But, use a low nitrogen fertilizer. Too much nitrogen can result in lots of foliage, with few flowers.

Keep the soil moist but drained, at all times. Plants are heat resistant, but need plenty of water. Water regularly during periods of drought.

Space smaller varieties 16" apart. The largest varieties should be spaced 2 feet apart, allowing ample room for growth.

Dahlias should be pinched back twice to promote bushier growth. Do so the first time after there is 3-4 sets of leaves on the stems.  

Dahlia grows quickly, and will bloom in mid summer. Stem tips will develop multiple buds, usually three. To grow bigger blooms disbud the two side buds, leaving the middle, terminal bud.

Dahlias will succumb to a hard frost. Dig up the tubers, and place them in a bed of dry sand. Store them in your cellar over the winter and replant them in the spring. You can mark the tubers with the flower color if desired. In warmer climates, provide winter protection by adding a thick layer of mulch.

Insect and Disease:

Dahlias can suffer from a variety of insects infestations. These include slugs, sucking insects, red spiders, and mites. Use slug pellets for slugs and snails. Apply insecticides or repellents regularly.

Disease problems can also occur. Treat early with a fungicide.

More Information:

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