Fundamentals of Growing Dahlias

Dahlias are among the easiest flowering plants to cultivate and reward gardeners with stunning blossoms from the middle of summer until the first frost of autumn. Growing dahlias is quite similar to raising tomatoes in many ways. If you already know how to grow tomatoes successfully, you will likely find growing dahlias simple and enjoyable. With proper care, these plants can bring vibrant colors and impressive flowers to your garden throughout the growing season.

Choosing the Right Dahlia Varieties

Dahlias come in an extraordinary selection of colors, shapes, and sizes. Gardeners can choose from countless varieties based on personal preference, photos from catalogs or websites, or recommendations from experienced dahlia growers.

Starting with just a few varieties is a great way to begin. Once established, dahlias will provide an impressive display of colorful and diverse blooms from around mid-July until the end of the growing season.

Finding Dahlia Plants and Tubers

There are several options for obtaining your first dahlia plants. Many large garden centers sell dahlia tubers, making them an easy and convenient choice for beginners.

Local dahlia societies are another excellent resource. These organizations often hold plant and tuber sales where gardeners can purchase healthy, locally grown plants while also receiving advice from experienced growers. Many societies offer ongoing support throughout the growing season, including question-and-answer sessions during meetings. Tubers from these groups are often high quality and well adapted to local growing conditions.

Another option is purchasing from specialized dahlia suppliers through mail-order catalogs or online stores. These growers focus specifically on dahlias and typically provide reliable plants, quality tubers, and expert knowledge.

When to Plant Dahlias

Dahlia tubers should be planted outdoors in spring after the soil has warmed and the danger of frost has passed. A useful guideline is to plant them around the same time you would normally plant tomatoes.

For gardeners who want earlier flowers, tubers can be started indoors about four weeks before the expected outdoor planting date. Growing them indoors in a bright location allows young plants to become established before being moved outside.

In most regions, dahlias can still be planted successfully as late as mid-June.

Selecting the Best Planting Location

Dahlias grow best in areas with good drainage and plenty of sunlight. A location that receives partial to full sun will encourage healthy growth and abundant flowering.

Growing dahlias in containers has also become increasingly popular. Large pots can provide a practical option for gardeners with limited space, as long as the containers provide adequate drainage and room for root development.

Planting Dahlia Tubers

Most dahlia varieties grow tall and require support. Installing a strong stake before planting is often the easiest approach. If a support is added after the plant begins growing, take care not to damage the developing tubers or roots. Tomato cages can also work well as simple supports.

Plant each tuber several inches below the soil surface with the “eye” facing upward. The eye is similar to a potato sprout and is the point on the tuber’s crown where new growth emerges.

When planting multiple dahlias together, leave approximately two feet of space between plants so each one has enough room to spread and develop.

Protecting Dahlias from Pests

Young dahlia plants are vulnerable to slug damage. Regularly checking plants in the early morning and removing slugs by hand can help prevent problems. Commercial slug-control products may also be used when necessary.

Japanese beetles are another common issue, especially when flowers are ready to bloom. One effective control method is picking the beetles from the plants and placing them into a container of soapy water.

Other insects may occasionally affect the appearance of flowers. Gardeners seeking perfect blooms can use insecticidal soap or approved pesticides, always following the product instructions carefully.

Growing Dahlias Organically

Dahlias respond very well to organic gardening methods. They are naturally vigorous plants that can produce large numbers of impressive flowers when grown in nutrient-rich soil.

A garden bed with plenty of organic material can support strong growth without relying heavily on chemical fertilizers. Many pest issues can also be managed through natural methods rather than chemical treatments.

Deer Resistance

Deer damage has become an increasing concern in many suburban gardens. Fortunately, dahlias are not among deer’s preferred food choices.

Although dahlias cannot be considered completely deer-proof, they are often ignored in areas where deer have access to other plants they enjoy more.

Watering and Fertilizing Requirements

Young dahlia plants require only moderate watering. Too much moisture can cause tubers and roots to rot. Once plants become larger, a general guideline is to provide water when rainfall is less than one inch within a week. Dahlias grown in containers usually need more frequent watering.

Before fertilizing, a soil test is recommended to determine pH levels and nutrient requirements. Without a soil analysis, dahlias generally benefit from regular applications of liquid or granular fertilizer.

Traditional growing practices suggest using a nitrogen-rich fertilizer during the earlier part of the season while reducing nitrogen levels later to encourage stronger flowering.

Maintaining Healthy Dahlia Plants

For gardeners growing dahlias mainly for enjoyment rather than competitions, only a few simple maintenance steps are needed to improve plant appearance.

Supporting the stems is important as plants grow taller. Tie the main stalk to a stake several times throughout the season, beginning near the lower section and adding additional ties as branches develop. A tomato cage can also provide support and may eliminate the need for frequent tying.

Another helpful technique is disbudding. Each branch often produces three buds at the tip. Removing the two outer buds allows the remaining flower to grow larger and become more visible. Leaving all three buds can cause blooms to become crowded and hidden among the foliage.

Removing some side shoots can also encourage longer stems, which are useful for creating elegant flower arrangements.

Preparing Dahlias for the End of the Season

Dahlias usually continue producing flowers until frost arrives. A strong freeze will kill the above-ground growth, leaving gardeners with two choices.

One option is to leave the plants in the ground and purchase new tubers the following spring. Another option is to dig up the tubers after the season ends, divide and store them, then replant them the next year.

A single dahlia plant can produce several new tubers during the growing season, allowing gardeners to expand their collection or share plants with friends. Proper harvesting and storage techniques will help ensure healthy growth when the next planting season begins.