I planted my first dahlias too early my second year of gardening. The soil was cold, the air had warmed up, and I lost half the tubers to rot before they even sprouted. Turns out almost everything on this list has the same issue.
Summer-blooming “bulbs” don’t go by the calendar. They go by soil temperature. Plant them too early into cold wet ground and they rot. Wait for the soil to warm and you get the summer color the bags on the rack promised.
Here are nine I plant every spring, with the zone notes and timing I wish someone had handed me year one.
The Short Version
- Most of these aren’t true bulbs. They’re tubers, corms, or rhizomes. The word “bulb” gets used loosely.
- Soil temperature beats the last-frost date every time. Wait for at least 55F (13C) soil, ideally 65-70F (18-21C) for caladiums.
- In zones 3-7, you’ll need to lift most of these in fall and store them over winter.
- Best starter trio: Dahlias for cutting, Caladiums for shade, Canna Lilies for instant scale.
Zone and Lift Quick-Reference
Before the individual entries, here’s the chart I wish I’d had year one. Whether you can leave each plant in the ground over winter, and when to start planting based on your zone.
| Plant | Hardy through | Lift required in | Planting depth | Soil temp min |
|---|---|---|---|---|
| Dahlia | Zone 9-10 | Zones 3-8 | 6 in (15 cm) | 60F (15C) |
| Gladiolus | Zone 7-10 | Zones 3-6 | 2-6 in | 55F (13C) |
| Calla Lily | Zone 8-10 | Zones 3-7 | 4 in (10 cm) | 60F (15C) |
| Canna Lily | Zone 7-10 | Zones 3-6 | 3-4 in | 60F (15C) |
| Caladium | Zone 9-10 | Zones 3-8 | 1-2 in | 70F (21C) |
| Elephant Ears | Zone 8-10 | Zones 3-7 | 2/3 buried | 65F (18C) |
| Pineapple Lily | Zone 7 (6 w/ mulch) | Zones 3-5 | 3-4 in | 55F (13C) |
| Tuberous Begonia | Zone 9-11 | Zones 3-8 | 1 in (2.5 cm) | 60F (15C) |
| Freesia | Zone 9-10 | Zones 3-8 | 2 in (5 cm) | 55F (13C) |
Soil temperature is the only number that matters for planting time. Air temperature can swing 15 degrees in a week. Soil temperature changes slowly and reliably. A $6 soil thermometer pays for itself the first season.
1. Dahlias for Constant Cutting
Dahlias are my biggest cutting flower every year. They bloom from midsummer until the first hard frost and the more you cut, the more they produce.
One thing nobody told me. Pinch the central shoot when the plant hits 12 inches tall. That breaks apical dominance and forces the plant to branch sideways into the bushy multi-bloom shape you actually want. Skip the pinch and you get a single tall stem with one flower on top.
One paradox worth knowing. Dahlias are native to cool Mexican highlands. They actually struggle in hot-summer zones (8-9) where nights stay above 70F. Cooler summer zones get better dahlia production. If you’re in the South, plant them where they get afternoon shade.
2. Gladiolus for Tall Borders
One gladiolus corm gives you one flower spike for about two weeks, then it’s done for the season. That’s the secret most lists skip.
The fix is succession planting. Plant a new batch every two weeks from your last-frost date through early summer. You’ll get continuous bloom from mid-July through early September instead of a single two-week window.
Tip: Stake every gladiolus when you plant it (don’t wait). A 12-flower spike on a 4-foot stem will topple in the first summer storm without support.
3. Calla Lilies for Elegant Pots
Calla lilies aren’t actually lilies. They’re Zantedeschia, a rhizome in the Araceae family (same as monstera and caladium). The name is sticky enough that no one bothers correcting it.
What matters: they want consistently moist soil but not soggy. Heavy clay or poor drainage rots them within weeks. Containers actually beat in-ground for calla lilies because you control the drainage.
Plant them with the rhizome eyes pointing up, four inches deep. They prefer full sun in cooler climates and afternoon shade in hot ones.
4. Canna Lilies for Instant Privacy
Cannas are the fastest tall screening plant on this list. From planting in May to six-foot tropical-looking stalks by late July, with bright flowers on top.
They also aren’t true lilies. They’re rhizomes in their own family (Cannaceae). The naming is messy. Just plant them.
In zones 7 and warmer you can leave them in the ground. In zone 6 and colder, dig the rhizomes in fall, cut tops to four inches, air-dry for one to two weeks, and store at 45-50F (7-10C). They’ll be ready to plant again next spring.
5. Caladiums for Dark Corners
Caladiums are the one bulb on this list I want to be honest about. They are not forgiving.
The deal-breaker is soil temperature. Caladiums need 70F (21C) soil minimum to grow. Not 60F. Not 65F. Most beginners plant them after the last frost when air temperature feels warm, and the tubers sit in 55-degree soil and rot underground.
The fix is patience. Wait until the soil holds 70F consistently, usually 2-4 weeks after your last frost depending on zone. Or start the tubers indoors in pots and move them outside once the soil is genuinely warm.
Once they’re going, the leaves are the showpiece. Pink, white, red, green, in patterns that look painted on. Worth the wait.
6. Elephant Ears for Massive Scale
The dramatic one. Single leaves grow to two or three feet across on some varieties and the whole plant can top six feet in a single season.
Plant the corm with about two-thirds buried and one-third of the neck sticking out. Full sun to part shade, depending on heat. Water deeply once a week. They drink like crazy when they’re putting on leaves.
One thing to plan for. Container elephant ears need a serious pot, at least 18 inches across, or the plant runs out of soil and the leaves stay small.
7. Pineapple Lilies for Something Weird
Pineapple lily (Eucomis) is the only entry on this list that’s actually a true bulb. The flowers look exactly like a small pineapple with a tuft of leaves on top.
Tougher than it looks. Officially hardy to zone 7, but I’ve seen it survive zone 6 with heavy winter mulch when planted six inches deep. The depth matters more than people realize for cold tolerance.
Easiest of the nine if you live in zone 7 or warmer. Plant once, leave in the ground, and they come back bigger every year for about a decade.
8. Tuberous Begonias for Hanging Baskets
The shade-garden hanging basket plant. Big rose-like blooms in pinks, reds, oranges, and creams, on plants that handle a shady porch better than most flowering options.
Plant the tubers hollow side up, just barely covered with soil. The hollow side is where the new shoots emerge. Planted upside down, they’ll fail every time.
Indirect light or morning sun only. The big soft leaves scorch in afternoon sun within a single hot day. If a basket is wilting badly, move it before you reach for the watering can.
9. Freesia for Sweet Fragrance
Freesia is the one on the list you smell before you see. The fragrance is honest sweet without being heavy, and it carries across a small garden.
Plant the corms two inches deep with the pointed end up, three inches apart. Full sun to light shade. They prefer cooler weather, so they bloom in early summer rather than peak heat.
This is the one I’d plant nearest a path or doorway. The scent is the whole reason to grow it. Tuck a small clump where you’ll brush past in the morning.
Frequently Asked Questions
When exactly do I plant if my last frost is May 1?
Don’t go by the date. Get a soil thermometer, push it 4 inches into the bed where you’ll plant, and wait for the morning reading to hit the minimum for each bulb (see the table above). For most of the nine, that’s 2-3 weeks after the last frost date. For caladiums, sometimes a full month.
When do I dig dahlias in fall?
Wait until the first frost blackens the foliage, then leave the tubers in the ground for one or two more weeks. That curing time toughens the skin and helps them store. Then dig, brush off soil, let them air-dry, and store in a paper bag with peat or wood shavings at around 45F (7C).
Why didn’t my caladiums come up?
Soil temperature, almost every time. They sit and refuse to grow until the soil is genuinely warm. Stick a thermometer in. If it’s reading 65F, your caladiums are just waiting.
Can I plant any of these in containers?
Caladiums, tuberous begonias, calla lilies, and elephant ears all do better in containers than in the ground for most home gardeners. Dahlias and gladiolus need bigger pots to thrive. Cannas are dramatic in large containers if you have the space.
Start With Just Two
If you’ve never grown summer bulbs before, don’t buy nine at once. Start with two. Three at the most.
Caladiums for a shady corner and dahlias for cutting are my picks for a first season. You’ll learn the soil-temperature trick the easy way, and by next spring you’ll have the confidence to add the rest. The patch by the path that’s all dahlia and caladium now started exactly that way.
Anh