Dividing plants is an essential gardening practice that rejuvenates perennials, expands your garden, and keeps plants healthy and vigorous. Proper plant spacing when dividing is crucial to the success of this procedure because it ensures newly separated plants have sufficient room to establish roots, grow well, and avoid overcrowding.
Plant Spacing Calculator for Dividing Plants
Why Proper Spacing Matters When Dividing Plants
When you divide plants, you separate the root balls or crowns into smaller sections and replant them. Each division is effectively a new plant that requires enough space to:
- Spread roots, absorb nutrients, and access moisture.
- Receive adequate sunlight and airflow to prevent fungal diseases.
- Grow unimpeded, reducing competition with neighboring plants.
- Produce healthy foliage and flowers.
Improper spacing leads to stunted growth, poor flowering, increased risk of disease, and plants that will quickly outgrow their area again, necessitating repeated dividing or transplanting.
When to Divide Plants
- Most perennials benefit from division every 2-4 years.
- Early spring or early fall is often optimal, allowing divisions to establish before hot or freezing weather.
- Signs a plant needs dividing include reduced flowering, congested growth, or plants becoming overcrowded.
How to Prepare for Dividing and Spacing Divisions
Step 1: Dig up the Plant
Carefully dig out the entire root ball or clump, taking care to preserve roots.
Step 2: Divide the Plant
Use a sharp spade, knife, or your hands to split the root ball into sections. Each division should have sufficient roots and shoots to survive independently.
Step 3: Prepare the Planting Site
- Loosen soil well in the new planting area.
- Amend soil with compost for fertility and good drainage.
- Remove weeds and debris to avoid competition.
Step 4: Follow Recommended Spacing Guidelines
Plant each division at the appropriate spacing based on the mature spread of the species or variety (see tables below).
Table 1: General Recommended Plant Spacing for Divided Perennials
| Plant Type | Mature Spread (feet/meters) | Recommended Plant Spacing (feet/meters) | Comments |
|---|---|---|---|
| Hostas | 2 - 4 ft / 0.6 - 1.2 m | 18-24 in / 45-60 cm | Slightly closer for smaller varieties |
| Daylilies (Hemerocallis) | 1.5 - 3 ft / 0.5 - 0.9 m | 12-18 in / 30-45 cm | Remain vigorous with adequate spacing |
| Shasta Daisies | 2 - 3 ft / 0.6 - 0.9 m | 18-24 in / 45-60 cm | Ensure good airflow to prevent powdery mildew |
| Sedum (Stonecrop) | 1 - 2 ft / 0.3 - 0.6 m | 12 in / 30 cm | Space closer if grown as ground cover |
| Bleeding Heart (Dicentra) | 2 - 3 ft / 0.6 - 0.9 m | 18-24 in / 45-60 cm | Prefers partial shade, allow airflow |
Table 2: Spacing Recommendations for Dividing Common Shrubs
| Shrub Type | Mature Width (feet/meters) | Recommended Spacing Between Divisions (feet/meters) | Notes |
|---|---|---|---|
| Hydrangea | 3 - 5 ft / 0.9 - 1.5 m | 3 - 5 ft / 0.9 - 1.5 m | Space for air circulation and growth |
| Lavender | 2 - 3 ft / 0.6 - 0.9 m | 2 - 3 ft / 0.6 - 0.9 m | Avoid overcrowding to prevent disease |
| Butterfly Bush (Buddleia) | 4 - 6 ft / 1.2 - 1.8 m | 4 - 6 ft / 1.2 - 1.8 m | Can grow large, needs ample space |
| Boxwood | 2 - 4 ft / 0.6 - 1.2 m | 2 - 3 ft / 0.6 - 0.9 m | Shrubs with dense foliage |
| Spirea | 3 - 5 ft / 0.9 - 1.5 m | 3 - 5 ft / 0.9 - 1.5 m | Dense flowering shrub |
Table 3: Dividing and Spacing Guidelines for Common Bulbous Perennials
| Bulb/Plant | Suggested Spacing (inches/cm) | Growing Habit | Notes |
|---|---|---|---|
| Daylilies | 12-18 in / 30-45 cm | Clump-forming perennial | Divide clumps every 3-4 years |
| Iris (Bearded) | 10-12 in / 25-30 cm | Rhizomatous perennial | Avoid overcrowding for rhizome health |
| Daffodils | 6-8 in / 15-20 cm | Bulb perennial | Plant new divisions at same depth |
| Tulips | 4-6 in / 10-15 cm | Bulb perennial | Typically planted in groups |
| Crocus | 3-4 in / 8-10 cm | Small bulbs | Plant dense clusters |
Table 4: Common Steps and Timing for Dividing Perennials and Spacing Considerations
| Step | Recommended Timing | Spacing Advice |
|---|---|---|
| Early spring division | Before new growth begins | Space based on mature plant size |
| Late summer / early Fall | After bloom and before frost | Ensure divisions have time to establish |
| Digging out clump | Cool, moist days preferred | Break clump into sections with healthy roots |
| Replanting divisions | Immediately after dividing | Plant at proper depth and maintain spacing |
Table 5: Soil and Preparation Tips for Divided Plants
| Preparation Step | Best Practice | Purpose |
|---|---|---|
| Soil loosening | Till or dig soil 12-18 inches deep | Encourages root penetration |
| Soil amendment | Add 25% compost or well-rotted manure | Improves fertility and drainage |
| Mulching | Apply 2-3 inches organic mulch after planting | Retains moisture, suppresses weeds |
| Fertilizing | Use balanced slow-release fertilizer at planting time | Supplies nutrients for growth |
| Watering | Water thoroughly immediately after planting divisions | Reduces transplant shock |
Key Tips for Successful Dividing and Spacing of Plants
- Choose healthy, vigorous parent plants for dividing.
- Make sure each division has at least 2-3 shoots and a good portion of roots.
- Follow species-specific spacing guidelines considering mature spread and growth habit.
- Prepare soil well to promote quick establishment.
- Water consistently for several weeks to encourage root development.
- Monitor plants closely for the first growing season to adjust spacing if needed (e.g., thin if plants crowd).
Common Mistakes to Avoid When Dividing and Spacing Plants
| Mistake | Why It’s Harmful | How to Avoid |
|---|---|---|
| Dividing too small sections | Plants become weak, struggle to grow | Ensure divisions have enough roots and shoots |
| Planting divisions too close | Leads to overcrowding and disease | Follow recommended spacing per species |
| Poor soil preparation | Roots struggle to establish | Amend and loosen soil adequately |
| Delayed replanting | Roots dry out, plants stress | Plant immediately after division |
| Neglecting watering | Divisions dry, fail to thrive | Water consistently after transplant |
Example: Repurposing Divided Plants for Garden Design
Dividing plants gives rise to multiple new plants, which can be spaced in ways to enhance your garden:
- Create flowing drifts of perennials with 18-24" spacing (hostas, daylilies).
- Plant hedges or screens with shrubs spaced closer (2-3 feet), thinning later.
- Use tighter spacing for ground covers like low sedums or creeping phlox.
- Consider sun/shade and moisture needs when spacing to ensure neighbor compatibility.
Summary
Dividing plants is a rewarding way to maintain your garden’s vigor while multiplying your plants. Proper plant spacing during replanting after division is fundamental for giving each division enough room to thrive, avoid disease, and bloom beautifully.
Use species-specific spacing recommendations based on the mature size and growth habit of your plants. Follow best practices for dividing, soil preparation, and watering to ensure success.
Tables provided in this guide serve as practical references for your dividing and spacing projects, making your garden healthier and more productive.