DAHLIA CARE
Growing dahlias at home is a relatively easy and rewarding way to add color and texture to your garden from midsummer through fall.
Planting
If possible, get your soil tested by your local extension office several months before planting your dahlias. You'll receive a report indicating your current soil's nutrient levels as well as the exact amount of each nutrient that needs to be added back to the soil for your plants' optimal growth.
Where: Dahlias appreciate well-draining, loose soil and at least 6 - 8 hours of full sun. If you live in an especially hot climate, they do well with afternoon shade.
When: Plant in late spring after all danger of frost has passed and the soil has warmed to 55 degrees.
How: Dig a 4 - 6" deep hole, break off any sprouts to 1" long and place the tuber horizontally with the eye (sprout) facing up if possible. Cover with soil and place a plant label.
Space dahlias 12 - 18 inches apart.
Sprinkle Sluggo around the planting area or the slugs may enjoy your sprouts before you see them.
Don't water dahlia tubers until you see sprouts emerge from the soil (usually takes 2 - 4 weeks after planting).
Staking: Dahlias appreciate staking to help support their large and prolific blooms. You can use a tomato cage or tie the main stalk to a wood or metal stake.
Growing
Pinching: If you'd like a stockier plant with more blooms, pinch off the top of your plant right above a set of leaves when plants are 8 - 12" tall.
Fertilizing: Dahlias respond well to fertilizer, but they don't need lots of nitrogen. Use a blend where the nitrogen content is half of the potassium and phosphorous content. Apply once a month and stop 4 - 6 weeks before anticipated first frost so as not to interfere with tuber development.
Watering: Once sprouted, water deeply 2 times per week, possibly more in hot dry climates.
Weeding: Dahlias have shallow roots and are particularly susceptible to herbicides, so hand weed only. Use mulch to cut down on weeding.
Pest Management: Insects such as aphids and thrips carry dahlia viruses from infected plants to healthy ones while feeding.
To keep aphid and thrip populations at bay, preventatively spray dahlia plants once a week with neem oil or horticultural oil.
Harvesting
Harvesting: For more blooms with long strong stems, harvest every 2 - 3 days making deep 18 - 24" cuts right above a set of leaves with sanitized floral snips.
Harvest flowers in the cooler parts of the day (early morning or evening). Strip the leaves from the stem so there's less to re-hydrate and plunge immediately into cold water for longer lasting blooms.
Move blooms indoors out of direct sunlight as soon as possible and let them re-hydrate for a few hours before arranging them. Adding a floral preservative to your water and changing your water daily will help preserve your blooms.
Deadheading: Be sure to remove spent blooms from your plant to keep it growing and blooming all season long.
Remember to cut deeply into the plant when deadheading just as you would when harvesting ripe flowers, rather than just snipping off the bloom. This encourages branching and more blooms.
Digging & Storing
You must take care that the tubers don't freeze at any point during the digging, washing, dividing and storing process because a frozen tuber is a dead tuber.
Digging: After the first frost, cut the plants back a few inches above the ground. Wait 1 - 2 weeks to begin digging tubers, if possible, to allow eyes to swell and make dividing easier.
When ready to dig, carefully loosen the soil 12" out from the plant with a digging fork then gently lift the tuber clump out of the soil. Don't shake the dirt off of it.
Washing: This isn't necessary unless you have sticky clay soil, but if you decide to wash the clumps let them air dry (not overly dry that they start shriveling) before dividing and storing.
Dividing: Tubers may be divided at this point, or you can wait and do it during the winter or early next spring. To cut down on virus and disease transfer, sanitize shears between each clump. There are videos online that demonstrate how to do locate the eyes and make cuts accordingly.
Storing: Tubers can be stored in several ways; ventilated cardboard boxes, paper bags, plastic bags, plastic wrap or large plastic storage tubs with peat moss or vermiculite.
They store best in a cool, dark, humid place where the temperature stays between 40 and 50 degrees F. Unfinished basements, cold storage areas or corners of heated garages where they're protected from freezing are all good options.
The goal for dahlia storage is to keep them moist enough they don't shrivel and dry enough they don't rot. This depends largely on your climate and storing location. If you live in a dry, arid climate, go for the plastic options to retain moisture. If you live in a humid environment, try the cardboard or paper bag options first to cut down on moisture levels. Check your tubers often during storage to make adjustments as need--more ventilation for too much moisture and more water (sprinkling) for conditions that are too dry.
