How to plant, transplant and divide plants during autumn

Planting

Autumn is a friendlier time for planting than summer- plants are preparing to enter their dormancy and the weather is cooler, which means a plant’s transpiration rates are lower and there’ll be less stress when their root system is disturbed from planting and transplanting. With the right care and consideration, you can still plant and transplant throughout the year, though avoid extremes in temperature.

When planting, it is a good idea to soak the plants root system in water with a dash of liquid seaweed. This acts as a tonic for the plant, stimulating the root system ahead of planting.

Choose the right position, according the plant’s requirements and dig a hole larger than the plant, incorporating soil with organic matter. Also, water the hole well, whilst making sure it is free draining, ensure the surrounding soil is hydrated for the plant.

Tilt the pot on an angle to slide the plant out and into the planting hole. The level of the top of the potting mix ideally matches the ground level of the soil and should not be higher or lower. If the roots are very dense or root bound, you can lightly tease the roots a little at the base and make a couple of cuts down the root system to direct the roots into the surrounding ground.

Do not press around the plant as this reduces the air holes and compacts the soil around the plant. Water the plant well and regularly- where the water penetrates the soil to the base of the root system and beyond- will encourage the roots to head down and establish widely. Incorporating a dash of liquid seaweed to the watering can can support the root system and reduce transplant shock.

Transplanting

Transplanting is simply moving the position of a plant already growing in your garden. It may be moving some self-seeded ‘volunteers’, dividing a perennial or changing the location of smaller shrubs. It is advisable to transplant deciduous plants in winter, when dormant.

The younger and smaller the plant, the more successful the transplant can be but don’t let this put you off more ambitious moves of larger plants. Some examples of easily transplantable plants include perennials like salvias, Agastache, achillea, as well as grasses, canna, crocosmia and self-seeded annuals. After relocating your plants, water them in well and deeply and prepare the hole well before starting the transplant.

When transplanting, your aim is to dig around the plant’s root zone so the plant can be dug up with as much root system intact as possible. With larger plants, get a helping had to lift the clump onto a tarpaulin then you can carry the tarp on opposite sides and move the plant to the hole. If the clump is dry beneath, it can be worthwhile again soaking the root zone in a wheelbarrow or a tub with a dash of liquid seaweed before planting.

Reduce the foliage to match the root system by pruning the plant so it appears ‘balanced’ above and below the ground, to help the plant establish well. By pruning off some of the foliage, the reduced root system has less foliage to support. If you are moving an herbaceous perennial, give it a hard ‘cut back’, pruning the foliage to ground level before moving the plant, making the whole transplanting process easier to see and handle.

Dividing plants

If you are planting or transplanting plants, it is worthwhile to consider if you can divide the plants at the same time and increase your plant numbers. Many herbaceous perennials and clumping plants can be separated into two, three or even more clumps to spread in your garden. Some great examples of this are Salvia, grasses like Themeda and other clumping plants like Kniphofia spp.

Once the root zone has had a soak and you have removed the plant from the pot or lifted the clump out of the ground, look to the base of the plant. There should be foliage coming from several places from the root zone. Using your secateurs, hori knife (or less precisely with a shovel) you can insert the blade down into the centre of and lever, separating the clump. Prise or cut the plant into several smaller clumps so that each clump has some foliage and a corresponding piece of the root system. You have now divided the plant and the smaller pieces can be planted or potted to share.