Dahlias Delight in Late Summer

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Oh, my aching muscles...

Spectacular dahlias are easy to grow
Dahlias are one of the most rewarding flowering plants you can have in your garden. Unless you want to grow dahlias for exhibition, they require very little care and attention. In return, you can enjoy blooms from July through the first frost of autumn. I’d say that’s a great deal!

When you talk to different dahlia enthusiasts, I guarantee you’ll get different opinions and advice from each one. It’s all great information to take and use for what works best in your own garden. Mother Nature is the real expert, especially here in the Northwest where second-guessing the weather is a regular pastime.

The first order of business is selecting the ideal location in your yard for a dahlia bed. Make sure your dahlias will receive four to five hours of sun per day. They can tolerate full sun, but don’t like strong heat.In the Puget Sound region, you’ll find dahlias thriving in full sun all day or half-day sun and shade.

Soil Preparation
Dahlias enjoy a very rich, well-drained soil. For all you technical types, a slightly acidic soil pH of 6.5 is best. Your soil should consist of a well-rounded mixture of sandy loam, topsoil, organic compost and peat moss. Look for a good three-way mix at the local nursery. Adding organic material throughout the year will keep your soil healthy and nutritious for growing dahlias.

Consider planting a fall cover crop such as winter rye in your dahlia bed after the dahlia growing and blooming season is over. Such cover crops can be tilled into the soil to enrich it in the spring before planting.
If you haven’t started a compost bin, here’s another good reason to do it! Mulching your dahlia bed in the fall will give a layer of organic matter more time to decompose into the soil and enrich the soil for dahlia planting.

Dahlias are planted from mid-April to mid-May, when all threat of frost is past. If we have a very wet, cold spring, wait until May to plant. You don’t want your tubers to rot before they have a chance to start growing. If weather conditions continue to be mild, April planting will probably be fine.

Dahlias grown from plants should stay in the cold frame until after any frost danger is past–probably mid-May.

When plotting my dahlia beds, I like to use six-foot stakes placed 2.5 feet apart. I place one tuber on each side of stake (two tubers per stake). Dig a hole about six inches deep. Loosen the soil and add a handful of bone meal to make a nice mixture for the tuber.

Take your six-foot stake and drive it about a foot deep in the center of the hole. Remember, there will be one tuber on each side of the stake.
Plant your tuber three to four inches deep if you have a heavy soil. In looser, sandier soils, plant tubers six inches deep.

Always stake your dahlias at planting time. If you wait until the plants are growing, you’ll dirve the stake through the tuber and ruin it. I purchase eight-foot long, one-by-two inch wood stakes and cut them down to six foot lengths. I like the look of wood, but it is also possible to use steel rebar. (They will never rot.)

Once you’ve placed the tubers with the eye closest to the stake, cover them with your soil/bone meal mixture. Label your stakes with the name of the dahlia variety. Don’t water the tuber until shoots begin to come up, usually in June. (This will, of course, depend on our unpredictable Northwest weather.) Many growers see their first blooms by mid-July.

NWGN archive published April 1998

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