If you’re gardening in zone 7, you might be wondering when to plant cannas for the best results. Getting the timing right is the key to a summer full of their dramatic, tropical foliage and vibrant blooms. This guide will walk you through the optimal schedule and simple steps to ensure your cannas thrive.
Planting too early risks frost damage, while planting too late shortens your growing season. By following the zone 7 calendar, you give these stunning plants the warm soil and long days they need to establish strong roots and produce those iconic flowers. Let’s get your cannas in the ground at the perfect moment.
When To Plant Cannas In Zone 7
For most of zone 7, the optimal time to plant canna rhizomes is in mid to late spring. You should aim for a period after the danger of the last frost has passed and the soil has begun to warm up consistently.
A good rule of thumb is to plant them around the same time you would plant tomatoes or other warm-season annuals. The soil temperature should be at least 60°F (15°C) for best growth.
Understanding Your Zone 7 Frost Dates
Zone 7 encompasses a range of climates, so your specific location matters. Generally, the average last spring frost date falls between early April and mid-April. However, microclimates in your yard can affect this.
- Early April: Warmer parts of zone 7, like some areas in Georgia or North Carolina.
- Mid to Late April: Common for many zone 7 regions, including parts of Virginia, Tennessee, and Oklahoma.
- Early May: Cooler, higher-elevation spots within zone 7.
Always check a local frost date calendar for your exact town. A surprise late frost can set tender new growth back, so it’s better to wait a week or two if you’re unsure. Your patience will be rewarded.
Pre-Season Preparation: Starting Cannas Indoors
To get a head start on the season, especially if your summers are shorter, you can start canna rhizomes indoors. This process gives them a 4-6 week jumpstart, leading to earlier blooms.
- Timing: Begin 4-6 weeks before your expected last frost date. For a mid-April last frost, start indoors in early March.
- Containers: Use pots that are at least 4-6 inches deep with good drainage.
- Planting: Plant the rhizomes horizontally, eyes facing up, about 2-3 inches deep in a quality potting mix.
- Care: Place them in a warm, sunny spot and water sparingly until growth appears, then water normally.
- Hardening Off: About a week before transplanting outside, gradually acclimate the plants to outdoor conditions.
Step-by-Step Guide to Outdoor Planting
When the weather is reliably warm, it’s time to plant. Here’s how to do it right.
1. Choosing and Preparing Rhizomes
Select firm, healthy rhizomes with at least 2-3 eyes (growth points). Avoid any that are soft, moldy, or overly shriveled. Soak them in lukewarm water for a few hours before planting to rehydrate them.
2. Selecting the Perfect Site
Cannas love sun and heat. Choose a location that receives at least 6-8 hours of direct sunlight daily. They will tolerate partial shade but may not flower as prolifically and might become leggy.
3. Preparing the Soil
These plants are heavy feeders and prefer rich, moist, well-draining soil. Work the soil to a depth of 12-15 inches. Incorporate 3-4 inches of compost or well-rotted manure to improve fertility and drainage. A balanced, slow-release fertilizer mixed into the soil at planting gives them a great boost.
4. The Planting Process
- Dig a hole 4-6 inches deep.
- Place the rhizome horizontally with the eyes pointing upward.
- Cover with 2-3 inches of soil. In cooler areas, a shallower planting (2 inches) helps the soil warm faster.
- Space rhizomes 1 to 2 feet apart, depending on the variety’s mature size.
- Water thoroughly after planting to settle the soil.
Caring for Your Cannas After Planting
Consistent care after planting ensures strong growth. Cannas need plenty of water, especialy during dry spells and when they are first getting established. Aim for at least 1 inch of water per week.
Apply a balanced fertilizer every 4-6 weeks during the growing season. As flowers fade, deadhead them to encourage more blooms. Keep an eye out for pests like Japanese beetles or caterpillars, which can chew on the leaves.
When to Plant Potted Cannas in Zone 7
If you purchase pre-started cannas in pots from a nursery, you can plant them a bit later. Wait until all frost danger is past, as the foliage is already developed and very sensitive to cold. The same soil and site preparation applies. Gently tease the roots if they are pot-bound before placing them in the ground at the same depth they were in the container.
Fall and Winter Care in Zone 7
In zone 7, cannas are often tender perennials. Whether they survive winter in the ground depends on your specific location and the severity of the season. In milder parts of zone 7, a thick mulch (4-6 inches) over the rhizomes after the first frost may provide enough protection.
Many gardeners choose to dig and store rhizomes to guarantee their survival. After the first frost blackens the foliage:
- Cut the stems back to 2-3 inches.
- Carefully dig up the clump of rhizomes.
- Let them dry in a shaded, airy place for a few days.
- Store them in a cool, dry place (like a basement) in peat moss or slightly moistened wood shavings. Check periodically for rot or drying out.
Common Problems and Solutions
Even with perfect timing, issues can arise. Yellowing leaves can indicate overwatering or poor drainage. A lack of flowers usually means not enough sun or too much nitrogen fertilizer, which promotes leaves at the expense of blooms.
Canna leaf rollers and rust fungus are occasional problems. Good air circulation, cleaning up debris in fall, and using appropriate organic treatments if needed can manage these issues effectively.
FAQ: Planting Cannas in Zone 7
What is the latest I can plant cannas in zone 7?
You can plant them as late as early summer (June), but they will have a shorter growing season and may bloom later or less abundantly. It’s always better to aim for the spring window if possible.
Can I leave cannas in the ground over winter in zone 7?
It’s a gamble. In protected areas or milder winters, heavy mulching might work. For guaranteed results, especially with prized varieties, digging and storing the rhizomes is the safest method.
My cannas didn’t bloom. What went wrong?
The most common reasons are planting in too much shade, planting too late, using a fertilizer too high in nitrogen, or a rhizome that is too young or small. Ensure full sun and use a balanced or bloom-boosting fertilizer.
How deep should I plant canna rhizomes?
Generally, 2-3 inches deep is perfect. In warmer, well-drained soil, you can plant at the deeper end. In heavier, cooler soil, plant a bit more shallowly to encourage sprouting.
When do cannas typically bloom in zone 7?
With a spring planting, cannas usually begin blooming in mid to late summer and continue until the first fall frost. Those started indoors will often bloom several weeks earlier.
By timing your planting correctly and providing simple care, you can enjoy the spectacular show of cannas all season long. Their bold presence in the garden is well worth the little bit of planning it takes to get them started right. Remember, warm soil and no frost are your guiding principles for success in zone 7.