Chapter 8

Division & Propagation

The fastest way to fill a bed is to grow one large clump for three years and then chop it into four plants in an afternoon. The plants don't mind. The gardener gets a free hosta bed.

When to divide

A hosta doesn't need division. A well-sited plant left alone for fifty years will simply keep getting bigger; the center does not "die out" the way an iris or daylily does. Divide because you want more plants, or to share, or to fit a redesigned bed.

Best time in Ohio:

• Spring (early April, just as noses emerge) — easiest to see the eyes, plant recovers fastest, top growth replaces in the same season.
• Late summer / early fall (mid-August through mid-September) — second-best window, gives roots 6 weeks to establish before frost.

Avoid dividing in the heat of midsummer (July). The plant is in full leaf, transpiration is high, and freshly-divided crowns can't keep up with water loss.

How to divide a mature clump

1. Water deeply the day before so the clump comes up with damp, intact roots.
2. Cut a circle around the clump with a sharp spade, about 4 inches outside the edge of the foliage. Pry from multiple sides until the rootball lifts. A large clump is heavy — recruit help or use a tarp.
3. Rinse the rootball with a garden hose. You don't have to — you can divide a dirty rootball — but rinsing lets you see the crown, eyes, and root structure clearly, and you'll make better cuts.
4. Identify the eyes. Each eye is a future growing point — in spring it looks like a pointed pink-white shoot; in late summer it's the base of a leaf cluster. A small clump might have 5 eyes; a giant one 40+.
5. Plan the cuts. Each division should have at least 3 eyes and a fist of roots. Smaller divisions survive but take a full extra year to look like anything.
6. Cut with a clean, sharp tool: a serrated bread knife for small clumps, a soil knife for medium clumps, an old wood saw for giants. Press straight down through the crown. Don't try to tease apart — clean cuts heal faster than torn tissue.
7. Sterilize the tool between any two plants if you have any concern about virus. A wipe with 70% isopropyl alcohol or 10% bleach is fine.
8. Plant immediately. Divisions in the new holes within 30 minutes is the goal. If you must hold them, wrap rootballs in damp newspaper and keep in shade — they're good for a day, marginal for two.
9. Water in heavily and shade for the first week if conditions are sunny or hot. An overturned bushel basket or a beach umbrella works fine.

Single-eye divisions

If you want to multiply a prized or expensive cultivar quickly, you can take single-eye divisions — each piece with one eye and a few roots. They live, but they look pitiful for two years before they amount to anything. Useful for collectors; not the right tool for filling a bed.

Other propagation methods, briefly

• Tissue culture is how commercial nurseries mass-produce hostas — sterile-lab work that's not practical at home but explains why a 'Patriot' from one nursery looks identical to a 'Patriot' from another nursery a thousand miles away. They are literally clonal copies of the same mother plant.
• Ross method (named for Don Ross): a vertical cut down through the crown of an actively-growing plant without lifting it, which forces the plant to produce extra eyes along the wound. Useful for collectors. Skip for now.
• Seed, covered in Chapter 2, is the only method that produces genetically new plants.

How a divided plant behaves

Year of division: smaller-looking plant, possibly skipping flowering, may produce fewer leaves than the original. Don't panic.

Year after: nearly full size, flowering returns.

Year two after: indistinguishable from a never-divided plant.