About Kenneth Joergensen Expertise Can answer questions about spring and summer bulbs: selection, soil preparation, planting, fertilizing, designing with bulbs. I can also give references where to buy the bulbs and how to store them. Besides the typical bulbs (tulips, daffodils, amaryllis, lilies etc) I can also answer questions about other geophytes, such as tuberous begonia, dahlias, etc. When to start indoors, light requirement, etc. My experience is in cool season areas, but I can answer questions about warm season areas if given time to research matter.
Experience Have worked with various bulbs (spring and summer bulbs). I am presently an allexpert advicer on the lawn message board also.
Question I would love to make a bed of nothing but dinnerplate dahlias,but don't know what kind of soil,best place to get them,and so on.I have been looking at some from Brecks,any help greatly appreciated.Even how far apart to plant them.I live in Northwestern Pa. Karen
Any type of soil is recommended, but drainage must be good. e.g. heavy clay can be lighted by the incorportation of organic matter. Sandy soil can be improved in the same manner to retain more water.
Select a sunny (minimum of 6 hours) location protected from strong winds. Dahlias grow best in a deep, fertile, well-drained soil with a pH of 6.0 to 6.5; they are not tolerant of water-logged soils.
I recommend digging the bed to a dept of 18-24" deep and mixing in a 3-5" layer of well composted cow manure, leaf compost or "humus" (available in bags from garden centers).
If your soil is already a good quality loam, amending the beds may not be required, but most uncultivated garden soils do well if amended with humus/organic matter.
Large tubers can be planted 2 weeks prior to last frost (e.g. about mid May) while smaller tubers (bedding dahlias) do better if planted after last chance of frost (Memorial day).
Dig a hole 8 to 10 inches deep which is wide enough to accommodate the tubers. Loosen the soil in the bottom of the hole and place the tuber with the eyes (sprouts) facing upward. Cover with 2 to 3 inches of soil. Soil should be filled in around the plants as they develop until the surface is level. Put a small stick at the side of the dahlia tubers. The larger stakes used to tie the dahlia goes in this hole later, but you want to mark the position now to avoid piercing the tuber later.
Apply a 3- to 4-inch layer of mulch such as pine straw, pine bark, or shredded hardwood mulch. Dahlias are heavy users of water; keep the soil moist but not saturated. Watering deeply twice per week is recommended. I strongly recommend buying some soaker hoses (made from recycled bicycle tires) and snake these through the bed.
Each dahlia tuber usually produces multiple shoots. While you can leave all the shoots to grow, thinning will produce flowers of higher quality. Leave one to four of the strongest shoots on each plant.
When plants are about a foot tall and display 3 to 4 pairs of leaves, pinch out the main growing point (terminal shoot) to encourage branching. One pinching is sufficient for most dahlias. Larger dinner plate dahlias should be staked to support the long stems and large flowers. Put the stake down when the plants are 12" tall and tie them with a flexible tie in a figure 8 loop so they have room to grow.
Flower size can be increased by removing lateral flower buds (referred to as disbudding). When the three buds that form at the end of each branch reach the size of small peas, remove the two side buds. This will dramatically increase the size of the middle flower.
Fertilize monthly with 1 tbsp of 15-30-15 miracle grow or 1 tbsp of 20-20-20 peters, or you can apply 1 tbsp osmocote pellets (nutricote, multicote, etc) twice per season.
Dahlia tubers must be lifted in fall after a first frost has blackened the foliage. Lift tubers and store dry and cool, but frost free, over the winter.
Planting tip:
stagger the spacing of the plants for best result:
e.g. like this
e.g. in summary:
- first preparre your garden bed. Till it deeply to a dept of 18-24" and incorporate a 2-4" layer of compost/humus. 1 cubic feet bag (at garden centers) will cover a 3 sq foot area, e.g. about 1 dahlia. If you plant 25 dahlias, you need minimum 25 bags of humus.
- plant dahlias at the bottom of an 8-10" hole and cover with a few inches of soil. as the sprouts go, hill soil back over the sprouts until the soil is level
- fertilize twice per year with osmocote, and/or make more applications with water soluble fertilizers.
- pinch back larger flowered dahlias when they are 12" high and tie them to the stake.
- disbud (remove two smaller flower buds) when the buds at the end of each stem is pea sized.
- water deeply on regular basis and use water soluble fertilizers to supplement.
May I recommend starting with a limited number of Dahlias as tending to "too many babies" can be a big chore. It is better to concentrate on 5-7 plants than a bed with 20 dahlias.
While Brecks do sell Dahlias, there are dedicated high quality suppliers such as swan island dahlias (www.dahlias.com).
Good sources for information on Dahlias include the Dahlia Socity (dahlias.org) and Colorado Dahlia Socity (very good) at dahlia.net.
