January - this time of year is a very busy one. There will be quite a few blooms making their appearance, especially if you left the tubers in the ground over winter.
Once the plants are 12 to 18 inches high, it is a good time to start tying them up, using a stretchy tie. You can pinch out the center tip and this will help the plant to branch out, resulting in more flowers. Once the plants are well established you may find it helpful to remove the bottom four or so leaves. This not only makes it easier to remove weeds, but also helps the air circulate around the plants which prevents the formation of "Powdery Mildew".

Later in the month as the buds start to develop it is time to begin debranching, especially if you intend to exhibit your flowers. If growing "Giants" you would allow for up to three blooms per plant, to gain quality and needed size. So you would leave two branches and the top growing shoot. As the size of the flower gets smaller, so the plant is allowed to bear more flowers. "Large" bloom varieties can have 4 or 5 flowers; "Mediums" 5; "Smalls" about 8, and "Miniatures" and "Pompons" are allowed to bear whatever they can, within reason. The flowers are borne on the end of the branch, so the number of flowers dictates the number of branches to be left on the bush.

Disbudding is another necessity and involves selecting which buds you are going to retain, and which need to be removed to facilitate longer stems, and the correct bloom size. The size of the flower i.e. Giant, Medium Small etc indicates the size of the actual flower, and not the size of the plant. Most regular dahlia cultivars grow between the heights of 3 feet and 5 feet. Dwarf varieties grow between 12 and 24 inches and are excellent for pots or front borders. You don't need to disbud dwarfs, just keep removing the dead heads to keep the display going all season long.

Watering will be necessary from now on, once the plants are well and truly through the ground. A good long watering either first thing in the morning before the sun gets on the plants, or early evening when the sun has gone off the beds are the best times. Spraying is also helpful to rid the plants of slugs, earwigs etc. You can use a combined fungicide/insecticide, and also add something like "Thrive" and achieve two jobs at once. Every three weeks or so should be sufficient to control pests and diseases.Scatter slug and snail bait around now and again to control ground pests. Look under the Pests and Diseases link for more information on this subject.