Cultural Instructions
When & Where to Plant
For best results, dahlias should be planted from mid April through May for most areas. Ground temperature should be approximately 60 degrees. (Exceptions will be hot climates). In general about the same time you would plant your vegetable garden. Dahlias need a sunny location to thrive. An area that receives at least 8 hours of direct sunlight is best. Exception for hot climates, they will need morning sunlight, afternoon shade. Less sun equals taller plants and less blooms.
Soil Preparation & Planting
Ground should be warm, well drained at planting, and in an open sunny location. If you have a heavier soil, add in sand, peat moss or bagged steer manure to lighten and loosen the soil texture for better drainage. Bone meal is ideal at planting time, put a small handful in the hole and work in well before planting tuber. PH level of your soil should be 6.5-7.0, slightly acidic. Do not amend dahlia beds with purchased top soils unless you are sure that it has not been treated in any way for weeds. Compost of any type should be avoided. Lay the tuber horizontally 3-5” deep, about 18” to 24” apart, and then cover with soil. DO NOT WATER TUBERS AFTER PLANTING!! Please wait to water until after the sprouts have appeared above the ground. The exception will be in hot climates, where they should be watered very lightly. Do not use bark dust or mulch to cover dahlias, as it does not allow the soil to warm up or tubers to sprout properly. This is a good time to apply snail and slug bait protect the new sprouts.
Container Growing
We do not recommend growing dahlias in pots, but if you choose to, low growing or dwarf dahlias work best in containers. Container size should be no smaller than 12” x 12” per tuber. Use 2 parts garden soil, 1 part potting soil that has not been treated in any way. Water sparingly, overwatering to keep soil damp will result in rotting tubers in the pots. After plants are 12” high, potted dahlias will require extra watering and fertilizing to promote proper blooming.
Staking
We recommend staking any dahlias that will reach 3 feet or taller. Any staking product will work, please check your local garden center – i.e.: tomato cages, metal rods, or bamboo stakes. Put your stakes in first, also put a label attached or at the foot of the stake so you can identify them and know which ones you really liked. I make a diagram and put it away so if the label blows off you will know which one is what.
Watering
Most areas have enough rain to fill dahlia water needs until the sprouts appear above the ground. After dahlias are established, a deep watering 2-3 times a week for at least 30 minutes with a sprinkler, more required during warmer dryer weather. Hotter climates will need to water more often as conditions require. Proper watering promotes proper blooming. Hand watering is not enough.
Fertilizer
Dahlias require a low nitrogen fertilizer, such as used for vegetables. We recommend high percentage potassium and phosphorus fertilizers such as a 5-10-10, 10-20-20, or 0-20-20. First applications should be within 30 days of planting and repeated again approx. 3-4 weeks later. One of the biggest mistakes made with dahlias is over feeding them. Avoid compost and high nitrogen water soluble types as they promote weak stems, small blooms, or no blooms, and tubers that rot or shrivel in storage.
Weed Control
Hand weeding is the only type of weed control you should ever use, there are no exceptions. Do not use any type of Herbicides, your dahlias will not survive.
Storing Tubers
If you are going to dig up your tubers and store for them for the winter. The time when you do this is after the frost has blackened the leaves and the plant looks awful. Cut the main stalk 6-8″ above the ground prior to lifting tubers out of the ground. If you have a tag on the plant tie it to the main stalk for identification purposes. After cutting the stalks wait one week. This will help next years eyes to form. Put the shovel or digging fork a potato fork is perfect too , 10-12″ away from the stalk do this all the way around the plant. Pry them up out of the ground be careful as to not break any tubers doing this as they ar fragile. If any tubers break off from the main clump with out an eye they are worthless. Wash tubers off with the hose thoroughly with your hand held sprayer, this will clean the tubers and make it easier for you to divide your tubers. Remove main stalk as this will cause rot on all of the tubers. Be careful when you cut and make sure you include a eye with every division.Make sure your knife is sharp this will make the job alot quicker and safer for you. Mark each tuber with a permanent marker and let them completely dry. Dip the cut sections of your tubers in Sulfur Dust this will hopefully keep your tubers from rotting. Be careful not to breath this dust as major respiratory problems can arise. Always read the labels. Store your tubers in a cool place such as an attic, basement or corner of a garage, temps need to be any where from 38*-60* the cooler it is the better there chance in survival for you to plant them in the spring.