Forsythia is a spring-flowering shrub with arching branches and early yellow blooms. Iowa State University Extension notes many cultivars have a spreading, arching habit and can reach 8 to 10 feet. Pruning at the wrong time is the most common reason for poor flowering.
Forsythia at a glance
| Type | Flower |
|---|---|
| Season | Perennial |
| Sun | Full sun |
| Plant spacing | 96 in |
| Row spacing | 96 in |
| Per square foot | 1 |
| Seed depth | At surface |
| Days to maturity | Blooms early spring on last year's wood |
| How to start | Iowa State says to plant in spring (April to early May) or late summer to fall (August through early November); bare-root plants should be planted in spring. |
| Water | 1 in per week |
These are the same numbers our plant spacing, square foot and harvest date calculators use. See every crop in the plant database.
When to plant forsythia
Iowa State says to plant in spring (April to early May) or late summer to fall (August through early November); bare-root plants should be planted in spring. Prune immediately after flowering, since pruning from mid-summer to late winter sharply reduces spring blooms.
How to plant forsythia
- Give full sun for the best growth and flowering. Partial shade is tolerated but produces fewer blooms.
- Plant in well-drained soil. Forsythia adapts to a wide range of soils but performs poorly in wet, poorly drained sites.
- Choose a cultivar for your winter lows. Flower buds of 'Meadowlark' and 'Northern Sun' bloom after exposure to -30°F; 'Sunrise' -20°F; Gold Tide -15°F; 'Lynwood Gold', 'Spring Glory' and 'Bronxensis' -10°F. Check your growing zone.
Caring for forsythia
Forsythia blooms only on the previous year's growth (old wood), and flower buds begin developing by early summer. For mature plants, remove one-fourth to one-third of the oldest stems at ground level every other year. To rejuvenate an overgrown plant, cut it to 3 to 4 inches above ground in late winter or early spring; blooms should return in 1 to 2 years.
Cultivar heights from Iowa State: 'Sunrise' about 5 feet, 'Northern Gold' 6 to 8 feet, 'Fiesta' 3 to 4 feet, Gold Tide 2 to 3 feet and 'Bronxensis' 18 to 24 inches. Use the plant spacing calculator to plan spacing.
Companion plants
| Grow nearby | Spring bulbs planted beneath the shrub |
|---|---|
| Keep apart | Wet, poorly drained sites |
Forsythia is among the earliest spring bloomers; pair it with crocus and hyacinth. Check other pairings with the companion plant finder.
Common problems
| Problem | What you see | What to do |
|---|---|---|
| Poor flowering with vigorous growth | Lush green growth but few flowers | Caused by cultivars with less cold-hardy buds or by pruning at the wrong time. |
| Flowers only on lower branches | Blooms limited to the base of the plant | Usually means the cultivar's buds are not fully cold-hardy and snow cover protected the lower branches. |
Not sure what you are looking at? The plant problem identifier ranks likely causes from the symptoms you see.
When and how to harvest
Forsythia is ornamental and not harvested. Iowa State reports few serious pest or disease problems in Iowa.
Plan your forsythia
- Plant spacing calculator: how many plants fit your bed
- Planting calendar: sowing and transplant dates for your frost dates
- Frost dates by ZIP code: your last spring and first fall frost
- Harvest date calculator: when your crop will be ready
Frequently asked questions
How far apart should I plant forsythias?
Space forsythias 96 inches apart in rows 96 inches apart. In a square foot garden, plant 1 per square foot.
How deep do I plant forsythia shrubs?
Plant at the same depth as the nursery container in a sunny, well-drained site.
How long do forsythias take to grow?
Blooms in early spring on last year's wood; prune immediately after flowering.
How much water do forsythias need?
About 1 inch of water a week, from rain and watering combined. Avoid wet, poorly drained sites; forsythia performs poorly there.
When do I prune forsythia?
Immediately after flowering. Pruning from mid-summer to late winter sharply reduces spring blooms.
Why isn't my forsythia blooming?
Wrong-time pruning, or cultivar buds that are not cold-hardy enough for your winter lows.
How do I renew an overgrown forsythia?
Cut it to 3 to 4 inches above ground in late winter or early spring.