Prop­a­ga­tion by cut­tings

Want free plants? Then get out your se­ca­teurs and take cut­tings from shrubs, climbers and peren­ni­als.

NZ Gardener - 365 Days of Flowers - - Practical gardening -

Tak­ing cut­tings is a great way to in­crease your stock of your favourite plants, but when you take your cut­tings will de­ter­mine how you need to take them. There are three main meth­ods: soft­wood, semi-ripe and hard­wood.

WHEN TO TAKE CUT­TINGS

Soft­wood cut­tings are taken in late spring to early sum­mer from the soft green tips of plants. They give the quick­est re­sults but they are also the most likely to fail. This form of prop­a­ga­tion suits many of the herba­ceous peren­ni­als and shrubs. Some soft­wood cut­tings, like those of be­go­nia and pe­largo­nium, can root in a glass of water, and can then be pot­ted up. Cut 7.5-10cm long stems from the tips of plants. Re­move the lower leaves but keep the up­per, then pot up into seed-rais­ing mix.

Take semi-ripe cut­tings in late sum­mer to early au­tumn when growth has slowed and the stems are firmer. This method suits ev­er­greens, climbers, shrubs and conifers. Take stems from the top or outer growth. They should be firm at the base but fairly soft at the top. Cut just un­der a leaf node, where growth hor­mones con­gre­gate.

Hard­wood cut­tings are taken in late au­tumn to win­ter, from ma­ture woody stems. This method best suits de­cid­u­ous shrubs and trees. Choose healthy stems 15-20cm long and about pen­cil thick­ness. It's im­por­tant to main­tain mois­ture lev­els (not too wet, not too dry) un­til the cut­tings form roots to take up mois­ture. Reg­u­lar mist­ing will keep cut­tings turgid un­til roots form.

DI­VID­ING PEREN­NIAL PLANTS

Plants, like chil­dren, ben­e­fit from be­ing sep­a­rated when they start to mis­be­have. The in­di­vid­ual plantlets in a swathe of phlox or Michael­mas daisies, for ex­am­ple, suf­fer from botan­i­cal claus­tro­pho­bia. Af­ter a few years, their con­gested cen­tres go bald, they don't grow as lush and their flow­ers are sparse. This is be­cause nu­tri­ents in their patch of soil are de­pleted, and since peren­ni­als spread by pro­duc­ing un­der­ground stolons or rhi­zomes, they nat­u­rally move out in their quest for new pas­tures.

To di­vide a patch, chop all around with a sharp spade. Then try to get un­der the roots and lever out the whole plant. Split clumps – ei­ther thrust two forks, placed back to back, into the clump and push the han­dles to­gether and the part­ing prongs will tear the clump nat­u­rally, or use a sharp spade. You may need to take an axe to old-timers. Small peren­ni­als can be split with a knife or old se­ca­teurs. Don't split clumps into hun­dreds of tiny pieces; you'll lose many of your off­sets. Trim un­wieldy roots, then re­plant di­vi­sions in fresh soil. Dis­card or pot up the bulk of the orig­i­nal plant. Three to five clumps are plenty to re­place one large peren­nial.

HY­BRID OR HEIR­LOOM?

Sav­ing your own seed is easy, but the type of plant you col­lect seed from will de­ter­mine the seed's vi­a­bil­ity. Open­pol­li­nated and heir­loom plants come true to type (they pro­duce seedlings just like their par­ent plant); hy­brids don't.

That's be­cause hy­brids are cre­ated by cross-breed­ing two com­pat­i­ble plants so that they pro­duce the best fea­tures of their par­ents. How­ever, seed that is pro­duced by hy­brid plants is ge­net­i­cally un­sta­ble, and likely to re­vert back to one of its par­ent's traits. So it's best to buy new seeds of hy­brid plants each year for sow­ing. Open-pol­li­nated and heir­loom plants, on the other hand, can be col­lected and sown, and re­main true to type year af­ter year.

Some plants are ster­ile, so ei­ther won't pro­duce seed or the seed is not vi­able. Cer­tain va­ri­eties of sun­flow­ers are nat­u­rally pollen-less, or male ster­ile (they pos­sess only fe­male char­ac­ter­is­tics). They are bred to have no pollen so that they make bet­ter cut flow­ers (they don't shed yel­low dust and are not al­ler­genic). Pollen-less sun­flow­ers still make seeds just like any sun­flow­ers if there are oth­ers with pollen nearby, though the seeds will yield flow­ers with dif­fer­ent traits, if sown.

Mop­head hy­drangeas pro­duce ster­ile flow­er­heads, so tak­ing cut­tings is the way to prop­a­gate these plants.

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