Root System Hormones

Root system hormones help cuttings to quickly form roots of their own. The hormones come in easy-to-use forms, and give good results, especially with ‘difficult’ plants.

When you make new plants from cuttings, root system hormones can mean the difference between success and failure. The preparations are sold in garden centres, nurseries and some high-street chain stores. They are economical, safe and easy to use.

root-system-hormonesHormones are chemical substances naturally made by plants and carried in their sap. There are special hormones to control particular types of growth: some help flowers to form and others help fruit to set. There are hormones that stop, or inhibit, growth, too. When you pinch out the growing tip of a Pelargonium or Fuchsia, you remove the hormone that prevents side shoots forming, so new side shoots will then grow below the pinched-out tip.

How hormones work

Synthetic, or man-made, hormones increase the plant’s own production of hormones, so the intended result – whether flowers, fruits or roots – is speeded up. With cuttings, speed is especially important. The sooner a cutting forms roots and can take up water and nutrients on its own, the less liable it is to die. Cut, using a sharp knife, and strip the bottom leaves. Dip the bottom 1 cm ( 1/2 inches) of the stem in the hormone powder, and pot up.

Powder, liquid or gel?

Root system hormones come in various forms. The most common is a dry powder, which is talcum plus a small amount of the synthetic hormone, naphthylacetic acid. It often contains the fungicide captan, which prevents rotting. There are different strengths of rooting powder: stronger for hardwood cuttings, weaker for softwood – as well as general-purpose powders. You can also buy rootliquid-rooting-hormone system hormones in an alcohol-based liquid. Cuttings taken from a resting plant can use the support of root system hormone powder.

‘Rooting gel’, sold in transparent plastic tubs, doesn’t actually contain hormones or speed up the rooting process, but it creates an ideal environment for encouraging new roots to form. Rooting gel is suitable only for softwood, or green, cuttings. All forms of rooting preparations are sold with clear instructions on how to use and store the product. Rooting gel does not contain hormones, but provides a very good growing medium.

Using rooting preparations

With rooting powder, dip the bottom 10mm (1/2 inch) of the cutting in the powder, then tap it a couple of times to get rid of any excess, so that just a thin layer of powder remains. Insert the cutting into compost immediately, before it can wilt.

With rooting liquid, dip in the end of the cutting, and leave it there for five seconds. The solution is quickly absorbed by the plant tissues.

With rooting gel, simply make holes in the foil lid, then insert the cuttings to half their length in the gel. Up to four cuttings fit in one tub.

Safety First

  • If using rooting powder, avoid breathing the dust.
  • Store root system hormones in a sale place and wash hands after use. Keep away from children and pets.
  • Cuttings taken from actively growing plants root more quickly than those taken from resting, or dormant, ones. Late spring and early summer are generally the best times to take cuttings, though Fuchsias and Pelargoniums can be successfully rooted in autumn. Always check individual plant cards first.

Choosing the right plants

Many house plants, such as Ivy, Creeping Fig or Goose-Foot Plant, grow ‘aerial’ roots along their sterns. With these, you can cut off rooted sections, pot them up, and treat them as independent plants from the start.

Some plants, especially cacti and succulents, do not benefit from root system hormones but root easily in rooting gel. This is also true for African Violet leaf cuttings.

Cuttings that most need help from synthetic hormones are wood ones, which take longest to form roots. Plants such as Creeping Fig and Ivy grow aerial roots on their stems.

FAQs

A friend of mine says root system hormones can kill cuttings from my Pelargoniums. Is this true?

Pelargoniums have hairy stems, and the hairs can hold large amounts of rooting powder. Too much root system hormone is harmful to a plant, so it is safer to use a rooting gel instead.

I know you’re not meant to let cuttings wilt, so why do you wait a couple of days between taking cuttings of succulents and planting them?

Cacti and succulents are accustomed to an arid environment and are far more likely to rot than to wilt, so it is important to let cut surfaces dry off and form a callous before planting them.

I want to take cuttings from my Grape Ivy, but am about to go away on holiday, and they might dry out if I plant them in compost. What should I do?

Pot up the cuttings in rooting gel, which will provide all the moisture they need for several weeks.

Keys to Successful Rooting

  • Always take cuttings from healthy plants and, if possible, do so during a plant’s active growth period.
  • Choose non-flowering shoots and remove any flowers that form during rooting.
  • Never let cuttings wilt. With thin-leaved plants, treat and plant the cuttings as soon as possible after they are cut.
  • Always remove any leaves that will be buried when you plant the cutting.
  • Keep the temperature at 20°C (70°F) and, it possible, provide bottom heat.
  • Protect cuttings from strong sunlight while rooting is taking place.

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