Growing Dahlias and Care of Dahlias

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Dahlia tubers  like well drained, medium ph soil that has at least half a day of sun;  full sun is best.  Peat moss and organic matter with some bone meal are  good soil additives.  Work in well 2 weeks or more before planting, or  apply in fall prior to sping planting.  Try not to use too “hot” of  organic matter.  A commercial fertilizer with equal parts nitrogen,  phosphorous and potassium, such as 16-16-16, works well at planting  time, but work it well into the soil so as not to burn the tuber  sprouts.   

April and May are ideal times to plant new tubers, as long as the ground is not too wet or cold.  Dahlias  will rot if the ground is too wet or cold and we cannot replace them if  the tubers have been subjected to this type of treatment.   It is  better to wait until the weather has warmed than to plant too early.   The tubers should be planted on their side with sprouts pointing  upward 3 inches deep and covered gradually as they sprout to give them a  good strong stalk and to protect the tuber ball from freezing under the  ground in winter.  A stake can be put in at planting time for tall  dahlias.  Do not water tubers at planting time unless ground is very  dry, they have moisture in them to get started. Use a good  slug,insect/cutworm bait. Earwigs and sowbugs can eat the new sprouts,  so be sure to inspect any damage carefully to be sure what is eating the  plant if you have a problem. 

Fertilize with a generic fertilizer when planting, like a 16-16-16.  When  plants are 12 to 18 inches high fertilize with a commercial or organic  fertilizer that is low in nitrogen, but high in phosphorous and  potassium to promote blooms, such as 5-10-10.  Again, read label content  or ask at your garden store.  Fertilize again when the plants are  starting to bloom well.  It is preferred to not fertilize after the  first of September or so as the roots could get soft. 

If you pinch the center of the sprouts out when the plants are 6 to 8 inches high, this will allow more  sprouts and gives a much bushier plant, and of course, more flowers.   Water the plants thoroughly and deeply every week, more if temperatures  are real hot and no rain has fallen. 

Cut dahlia flowers in the cool of the day.  Bring indoors and place stems in 2”  of hot water, 160 F.  Leave in the hot water until it cools or until  the stems turn dark at the ends.  Flowers can be re-cut and arranged as  desired.  The hot water gives them a longer life and can even liven up  wilted blooms.  A commercial additive and a couple drops of bleach added  to the water of fresh flowers helps as well. 

Insects can be a problem.  2 spotted spider mites attack the plant from the ground up and turn the leaves yellow  and then brown as they suck the juice out of the plant.  A commercial  miticide or insecticidal soap can be used.  Green spotted beetles (bean  beetles, cucumber beetles or 7 spot) can be a pest to the blooms, use of  a commercial insecticidal soap, in conjunction with an insecticide will  help reduce these pests.    Fungicides may be necessary if mildew is a  problem, usually in the Fall, but also if you water heavily on the  leaves.  Please follow all chemical label directions carefully.