Rhizomes

A rhizome is a stem that grows laterally at about the soil surface, although in some plants it is underground. Normally, a rhizome stores food, but the degree to which it does this varies from species to species.

A rhizome is a perennial, and it is propagated artificially by division at an opportune season of the year: in most cases this is after flowering, when the rhizome is about to extend and produce new roots.

It has two ways of growing. In one, typified by the German or bearded iris, a terminal bud develops and flowers; the plant sends out extension growth through a lateral bud. The following season, this extension growth develops its own terminal bud, which flowers, and the plant continues to extend through its lateral buds. In the other way of growing, typified by mint and couch grass, its extension growth develops continuously from the terminal bud and occasionally from a lateral bud, which usually produces flower spikes.

In habit, rhizomes may also vary: "crown" rhizomes, such as asparagus, have virtually no extension growth annually and develop as a spreading crown, whereas other kinds of rhizomes, such as mint, couch grass and

ground elder, make rapid and continuous growth and spread over large areas of ground in a relatively short time.

Perhaps the most prolific of garden plants to be propagated using rhizomes are bearded irises. The best time to divide their rhizomes and establish new plants is immediately after flowering, when the old root system dies down and a new root system begins to develop. Lift the clump of rhizomes with a fork and knock off as much soil as possible. Cut away and discard any old rhizomes, just leaving the current season's flushes of growth. Cut back their roots to 2-3 in, and shorten the leaf blades to reduce water loss before the new root systems develop. The prepared rhizomes are now ready for planting.

As a general rule, a rhizome should be replanted at the same depth as it was growing; for irises this is more or less in the surface soil. Usually, a rhizome has two rows of roots longitudinally on each side underneath. Therefore, when replanting, dig out two linear shallow trenches and' place the roots in these. Firm back the soil over these roots and label the rhizome clearly. If necessary, settle in by watering.

1 Divide rhizomes after flowering, when the old root system dies down.

2 Lift a clump with a fork. Knock off as much soil as possible from the roots.

3 Cut away and discard any old rhizomes from the current season's growths.

isiifhl/i.i ifxlnae) Canna

Moth«Hn-law'j tongue

'iiilnnidii mmI i/'ii/yx<>n,ittiml Ihisili", c rwping

CROWN RHIZOMES

Less easy to propagate are the "crown" rhizomes, such as peony and asparagus, which have what is traditionally referred to as herbaceous perennial rootstock. Fairly massive cuts are needed to divide such rootstock into suitable pieces for propagation: each pigce requiring at least one well-developed bud.

Divide crown rhizomes in late winter before the buds enlarge and before the new season's root system begins to develop. Make a few relatively large divisions, unless quick bulking-up is essential, when it is better to plant small divisions in pots filled with John Innes No. 1 compost or similar (see page 12) in order to give them good conditions in which to become established. Dust the cut surfaces thoroughly with a fungicide to prevent bacterial and fungal rots. Leave them in a warm (21°C/70°F), dry atmosphere for the surface to dry out and develop the beginnings of a protective corky layer. Then plant out the divisions. Label them clearly.

2 Dust the cut surfaces with a fungicidal powder.

3 Plant out after two days in a warm, dry area.

1 Divide crown rhizomes in late winter.

2 Dust the cut surfaces with a fungicidal powder.

3 Plant out after two days in a warm, dry area.

5 Replant each rhizome on a ridge with its roots in trenches either side.

4 Shorten the leaf-blades and cut back the roots to 2-3 in.

5 Replant each rhizome on a ridge with its roots in trenches either side.

6 Firm back the soil over the roots. Label and settle by watering.

Was this article helpful?

0 0
Organic Gardeners Composting

Organic Gardeners Composting

Have you always wanted to grow your own vegetables but didn't know what to do? Here are the best tips on how to become a true and envied organic gardner.

Get My Free Ebook


Post a comment