Six propagation mistakes to avoid

When carried out correctly, propagation allows you to boost your stock of plants, for free. However, there are some pitfalls to avoid, to ensure your seedlings, cuttings or divisions grow into mature, healthy plants.

Using the wrong compost

It's tricky to find one compost type that can be used for all types of propagation. However, you can tailor a compost to suit your needs. Multi-purpose compost with perlite mixed in will suit most softwood cuttings. You may want to mix in coarse grit instead, if you're taking semi-ripe or hardwood cuttings – these take longer to root and benefit from a heavier, more stable mix.

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If sowing seeds, use a fresh bag of seed compost (check the sell-by date), and sieve it to remove the larger bits of organic material. In general, avoid heavy soil mixes, as these can encourage fungal growth and root rot.

Allowing plants to dehydrate

Placing penstemon cuttings in a sandwich bag

Plants are always losing water from their leaves, so cuttings (which don't have roots to draw in water), are especially prone to drying out. When taking cuttings, ensure you have a plastic sandwich bag containing a little water with you, to place your cuttings into. It's also worth reducing water loss by removing the lowest pairs of leaves from each cutting, and snipping the leaves of larger-leaved plants in half.

Another way to reduce water loss is to keep the cuttings in a humid atmosphere – place a clear plastic bag over individual pots or use a propagator with a lid.

Dividing overly small rootballs

How to propagate lungwort — Dividing a pulmonaria

Division is a great way to reinvigorate tired and congested perennials. The best time to divide is generally spring for late summer- and autumn-flowering perennials, and autumn for spring- or summer-flowering perennials that have finished their display for the year. It's important to ensure that each new division has at least one shoot or rosette, as well as a healthy root system, even if it's small. Compost any divisions that look withered or soft.

Video: Carol Klein divides and replants a clump of daylilies

Using the wrong propagation method

There isn't one type of propagation that will best suit all plants. You might think sowing seeds is the quickest route to propagating some plants, when actually you'd be better off taking cuttings instead. Hellebores, for example, dislike root disturbance so shouldn't be divided - they're best grown from seed. Hydrangeas on other hand are too large and woody to divide, but it's easy to take hydrangea cuttings from softer wood.

If you're ever unsure, spend a little time researching the plant you want to propagate to find out the best way to do so.

Planting out too soon

Young plants, whether they're new cuttings or seedlings, will be more susceptible to damage from low temperatures and pest damage than established plants. Cuttings and seedlings, especially those of tender or half-hardy plants, will require a period of hardening off in the UK to acclimatise them before they're planted outdoors. A cold frame is the perfect solution, protecting young plants from the worst weather while not coddling them with warm temperatures. Regularly look out for signs of pests, such as nibbled leaves or slimy slug trails, and dispose of them when found.

Aim to pot on your cuttings and seedlings when you spot roots poking out from the bottom of the container.

Video: Monty Don pots on rooted delphinium cuttings

Not providing your plants with enough light

Zinnia seedlings ready to be potted on individually

Low light levels will hamper the growth of seedlings, particularly indoors. Without strong light levels, seedlings will be weak and spindly, and more prone to the fungal disease, damping off. If sowing indoors, choose a bright, warm spot, such as a windowsill, and check the seedlings daily. Don't let the compost dry out completely, but don't let your seedlings sit in waterlogged soil either.