How to Grow Dahlia? Detailed Guide to Planting Methods and Key Techniques

AbstractCutting propagation: The substrate can be made from garden soil or leaf mold mixed with an appropriate amount of river sand. Take cuttings from February to May. After inserting the cuttings, firm the soil and water thoroughly. You can cover with plastic film or build a shade shed, and uncover the film daily for ventilation. Planting out: About 30 days after cuttings are taken, they can be planted out, with a plant spacing of 30cm and a row spacing of 40cm. After the seedlings recover, pinch off the growing tips, and carry out regular hoeing and weeding. Fertilizing: Dahlia is a heavy feeder. Apply sufficient basal fertilizer before planting, and apply appropriate topdressing during the early growth stage and the bud stage.

I. Preserving Stock Plants

When digging up stock plants, remove the entire root system with its soil, keeping only a small amount of soil around the heart of the plant and clearing away the rest. Then dig a trench and lay the stock plants in neatly; no gaps are needed between them. After arranging them, cover with a layer of soil, level with the ground surface, and finally water thoroughly. To overwinter and preserve stock plants, the temperature should be kept at around 0-5°C.

II. Cutting Propagation

1. Selecting cuttings

(1) At the end of March, the stock plants stored over winter can be planted out in a greenhouse, with a plant spacing of about 30cm and a row spacing of about 40cm. Prune the stock plants appropriately and strengthen water and fertilizer management.

(2) Cuttings are generally taken in spring from February to May, depending on the quantity of propagation material available. For example, if the cuttings are taken from the basal shoots sprouting from overwintered ground-cover chrysanthemums (Dendranthema morifolium), cut vigorous young shoots about 8-10cm long as cuttings, then soak them in water and insert them as soon as they are collected. Before inserting, to reduce water transpiration, remove the leaves at the base of the cutting, keeping only three or four leaves at the top.

2. Taking cuttings

(1) Cuttings can generally be taken in a cutting bed or seedling tray. A substrate can be prepared by mixing garden soil or leaf mold with an appropriate amount of coal cinders or river sand, then spray the bed surface with a 400-fold dilution of 25% carbendazim for disinfection before taking cuttings.

(2) The insertion depth is generally one-third of the cutting. After inserting, firm the soil and water thoroughly. To increase air humidity, spray water around the cutting bed. To prevent direct strong sunlight and reduce water evaporation, build a shade shed in good time, generally covered with a layer of plastic film, which helps retain heat and moisture.

(3) Generally, from 9 a.m. to 4 p.m. each day, uncover the film for ventilation as appropriate according to the specific temperature. After about a week, the cuttings will take root. You can then appropriately reduce the amount of spraying so that the soil is kept just moist, and then remove the film.

(4) Cuttings of ground-cover chrysanthemum generally root easily at a temperature of 15-20°C. If the temperature is too high, the cuttings are prone to rot; if too low, the rooting time is prolonged.

III. Planting Out

1. Dahlia can generally be planted out about 25-30 days after cuttings are taken. They can be grown in pots or planted out in fields. For field planting, the plant spacing is 30cm and the row spacing is 40cm. Once the plants have recovered from transplanting, pinch off the growing tips in good time. To encourage more branching, keep only 4 leaves at the base.

2. In the early growth stage of dahlia, to improve soil aeration, regular hoeing and weeding can be carried out. The plant is suitable for growing in fertile, well-drained sandy loam. It dislikes waterlogging, so drainage must be timely in the rainy season. When the plant grows to 20-30cm tall, fertilizer can be applied together with earthing up. Apply cake fertilizer near the plant, then earth up.

IV. Fertilizing

Dahlia is a heavy feeder. Before planting out, apply sufficient basal fertilizer; about 1000-1500 kg of decomposed farmyard manure can be applied per mu. In the early growth stage of the plant, topdress with cake fertilizer, urea, etc. Especially during the bud stage, spray with 0.2-0.5% potassium dihydrogen phosphate and 0.1% urea solution once a week, which helps promote rapid plant growth, bright flower colors, and deeper green foliage.