WHY GROW DAHLIAS? They keep getting better and better in late summer and autumn when many plants are fading. They offer opulent flowers with lush colors and astonishing forms. And the more you cut them for bouquets, the more they bloom.
HISTORY — Dahlias were brought into gardens by the Aztecs, arrived in Europe in 1789, and by the 1840s garden writers in America were hailing scores of new varieties every year. Exciting new cactus forms were introduced in the 1870s, and in 1927 F. F. Rockwell reported that dahlias ranked in “the leading position of all bulbs grown in America.”
DAHLIA ARCHIVES — For customer tips and raves, the stories behind the bulbs, links and books, history, news, and more, see our Dahlia Newsletter Archives.
DAHLIAS AS CUT FLOWERS — For tips for longer lasting dahlias in bouquets, see our Bulbs as Cut Flowers page.
TIPS FOR SUCCESS — Dahlias prefer full sun and rich soil. Blazing hot summers are hard on them, but see our tips for the Deep South, below. Yes, you’ll need to stake them, but it’s easy. No, you don’t HAVE to dig and store them — it’s not a law in any state! When they freeze dead, just add them to the compost pile. We send complete instructions with all of our bulbs.
PLANTING & CARE — DON’T plant outside too early! Wait till after all danger of frost is past — when you’d plant tomatoes or later. Or you can start them inside 4-6 weeks early and transplant them outside when it warms up, which is what we do here at Old House Gardens.
Dahlias thrive in light, fertile, well-drained soil. If your soil is heavy (clay), add organic material or plant in raised beds. Full sun is best, but eight hours will do. Dahlias do NOT like extreme heat, so avoid hot spots such as near south or west walls.
If you garden in zone 8(10WC) or warmer, check out our special advice at oldhousegardens.com/DahliasForHotNights .
Space your dahlias 18-24 inches apart. Dig a hole a foot deep and wide; enrich the soil and return some to the hole. Pound a sturdy stake into the ground near the center of the hole so that 4-6 feet of it remain above ground level (depending on the ultimate height of the dahlia). In front of this, lay the tuber horizontally with the eye, if visible, pointing up – or set the entire pot-root cluster with the stem facing up – about 6 inches below ground level. Cover with 2-3 inches of soil. If your soil is moist, DON’T WATER tubers until they sprout. In soggy soil, un-sprouted tubers are prone to rot. If your soil is dry or the weather is hot, you will need to water, but don’t overdo it – till sprouts emerge.
As shoots grow, gradually add soil till the hole is filled. For bushier plants, “top” them after they get three sets of leaves by pinching or cutting out the center shoot. If slugs or snails are a big problem for you, consider bait.
Water regularly during the growing season, and fertilize lightly every 3-4 weeks until early fall. Don’t over-feed! AVOID HIGH NITROGEN FERTILIZERS such as lawn fertilizer. Use rose, tomato, or general garden fertilizer instead. Hand-weed; avoid ALL herbicides. Tie stalks to the stake as they lengthen. Double strands of garden twine work well. Dead-head by cutting spent blooms to encourage more vigorous flowering – or simply pick lots of bouquets! Dahlias like cool conditions (they are native to the mountain plateaus of Mexico), so growth and flowering peak as temperatures cool in late summer and early fall.
FOR EVEN MORE INFORMATION on growing dahlias, including how to store tubers over the winter (IF you decide to do that), click here for our spring Planting and Care page.