WHEN TO PLANT
Dahlias are planted in the spring when the ground temperature is approximately 15 degrees or warmer. Generally, when you would plant your veggie garden. Planting times vary depending on your exact climate. For example, cooler climate areas of Australia planting usually begins just after Melbourne Cup Day when any danger of frost has passed.
WHERE TO PLANT
Dahlias need a sunny location to do well. The more sun the more blooms. It is recommended that dahlias receive at least 6-8 hours of sunlight per day. They can be grown with less sun, but that less sun means less blooms and taller plants, reaching for the sun. Of all dahlias to consider growing with less sun, the lower growing and dwarf dahlias will do the best. In hot climates, morning sun with some afternoon shade may be best for proper growth. Some varieties with white tips can burn. Please remember dahlias require deep water 3 times a week or more during the growing season to bloom accurately.
Dahlias need warm, well-drained soil. Your dahlias will do best when planted in your existing garden or yard soil. If you have heavier soil we recommend amending it with peat moss to help lighten it up. Do not amend dahlia beds with purchased topsoil or potting mix unless you are sure that it has not been treated in any way for weeds or fertilisers with harmful chemicals. This can burn your dahlia sprouts and cause them not to grow at all. Even if you think you do not have the best soil, this soil may be better than bringing in new soil.
To increase the nutrients in your soil the best all-around soil additive would be Alpaca manure. If you choose to add compost to your dahlia beds, do it sparingly. Most types of compost are high in Nitrogen, which promotes tall spindly plants, small blooms, fewer blooms, and tubers that are weak in storage. If you are planting a new dahlia bed, make sure to check all soil, potting soil, and materials being used carefully. The soil must not be sterilized or contain any type of weed killers (herbicides), or compost, or fertilisers. If weeds won’t grow in the soil, neither will your dahlias. Although many herbicides on the market state they are safe for dahlias, we disagree as we have seen negative results. Hand weeding is the only option when growing dahlias. The PH level of the soil should be 6.5-7.0, slightly acidic. To adjust the PH level in your soil you may add Lime to increase your PH level, or gypsum to decrease your PH level.
Dahlias are as unique as people are. They come in all shapes and sizes. Tuber size will in no way affect or control the growth or performance of the plants. Some of our largest dahlias produce the smallest tubers, but always produce the biggest healthiest plants and massive blooms. A larger tuber will bloom about 1 week earlier than a small tuber. However, a smaller tuber will produce more tubers. It’s recommended you don’t judge a tuber by its size. All tubers are guaranteed to grow and produce beautiful flowers.
Your tubers will be packaged in a paper bag with untreated chemical free wood shavings, and you will be able to identify each tuber with the name on the bag. Some tubers will show sprouted eyes and others may have dormant eyes when you receive them. All tubers are guaranteed to grow and produce beautiful flowers.
Dahlias are ready to go in the ground when your ground temperature has reached 60 degrees or warmer. Be sure that your soil is workable and not waterlogged. The ground should be warm, well-drained at planting, and in an open sunny location.
Planting dahlias too early, in cold wet soil, may result in rotting tubers. Dig a hole 10cm deep, lay the tuber horizontally on its side, then cover it completely with soil. If the tuber sprout(s) is longer than 5 or 8cm in length, it would be best to trim/pinch them back to a length of 2.5cm. This will not hurt your dahlias, in fact, this will help them have a stronger stalk pushing through the soil. We recommend planting 30 – 40cm apart.
Bone meal is ideal at planting time, put a small handful in the hole and work in well before planting tuber. However, beware if you have pets or other animals around, they are attracted to bone meal and may dig up your tubers, so we recommend skipping this step.
This is the ideal time to put in your garden stakes. AT THIS POINT YOUR DAHLIAS DO NOT NEED MUCH WATER UNLESS YOU ARE GROWING IN CONTAINERS (See container growing instruction). Begin your watering regimen AFTER sprouts have appeared above the ground. There is an EXCEPTION in hot climates and/or container growing, where you will need to be sure the soil is slightly damp at planting as tubers do need a small amount of moisture to get going
At this point do not cover your dahlia beds with bark dust or any other mulch as this will prevent the ground from warming up and allowing your dahlias to get growing. Snail and slug bait should be applied immediately. Continue applying slug and snail bait until you see your dahlias up and growing and throughout the season to protect them. The average time for dahlias to sprout through the ground is 3-5 weeks.
We recommend staking dahlias. The best time to stake your dahlias is during the planting process. This will avoid unnecessary damage to the tuber later. Any staking product will work, including tomato cages, metal rods, bamboo stakes, etc.
Most areas have enough rain to fill dahlia water needs until the sprouts appear above the ground. If, however, you are planting in a hot and dry climate, you will need to water once a week to help the tuber establish its root system.
STARTING YOUR DAHLIAS INDOORS
Start your dahlias approximately 6 weeks before transplanting them outside. Be sure your last frost date has passed, as the delicate plant will freeze and die back. We recommend starting your dahlia tubers in potting soil, peat moss, or a combination of the two.
The planting medium should be 2/3 garden soil/topsoil to 1/3 potting soil or all garden soil. Potting soil alone is porous, dries out too quickly, and will cause poor growth and blooming results. Be sure that the potting soil and garden soil used are not sterilized or treated with any type of weed killer or herbicide. Avoid potting soil that includes high nitrogen fertilizers, compost, etc., as they will burn and rot the tubers.
The tubers should be planted 5 to 8cm deep, covered completely, in a warm area above 15 degrees, and a location where they will receive at least 8 hours of light once the sprouts emerge. The planting material should be kept slightly damp and not wet. (Dahlias can rot or develop poorly if the soil conditions are too wet.)
We recommend hardening off (putting them out during the days and bringing them in at night) your dahlias before transplanting them to help them transition. Transplant your dahlias in your beds after the danger of frost is past. The ground temperature should be approx. 15 degrees or warmer. Plants should be about 30cm tall or less when you move them outdoors. If the plants are over 30cm high, pinch them back to about 15cm above ground level before transplanting. Be sure to plant the tuber 15cm deep. After transplanting your dahlias into your beds, be sure to keep them damp and well-watered for at least a week until the roots are established. Once your dahlias are established, care for your dahlias as you would tubers planted directly in the ground.
In general, dahlias do not do as well in pots or containers as they do directly in the ground. If you choose to grow your dahlias in pots or containers we recommend using the low growing or dwarf varieties of dahlias, as they are easier to maintain. When choosing a container be sure that there is adequate room for tuber growth.
The planting ratio should be 2/3 garden soil/topsoil to 1/3 potting soil or all garden soil. Potting soil alone is porous, dries out too quickly, and will cause poor growth and blooming results. Be sure that the potting soil and garden soil used are not sterilized or treated with any type of weed killer or herbicide. Avoid potting soil that includes high nitrogen fertilisers, compost, etc., as they will burn and rot the tubers.
GROWING DAHLIAS IN CONTAINERS
The difference in growing in containers rather than the ground is they will need water to get started growing for you. Please make sure to keep your soil slightly damp – or cool to the touch after planting, not soaking wet. After planting and until you see the sprouts above the soil level, water sparingly. Overwatering to keep the soil wet will result in rotting tubers.
Once the dahlias have sprouted above the soil, water as often as you would any other container plants. After plants are 30cm high, potted dahlias will require extra watering and fertilizing to promote proper growth and blooming. We recommend fertilizing dahlias in containers much more often than those planted directly in the ground.
Dahlias need to be watered for proper growth and blooming. We would suggest watering 1 to 2 times per day once your dahlias are above the ground. Fertilise approximately every 2 weeks with worm tea until flower buds begin to appear then swap and use a fish/kelp fertiliser. We use our home-made worm tea.