Planning ahead for the autumn planting season
Why autumn is the strongest season to establish new planting, and why the groundwork begins now
Autumn is the strongest season for planting most hardy trees, shrubs and hedging in the UK, and the reason lies below ground. Soil that has warmed through summer holds its heat well into the season, while the air cools and the rain returns. In these conditions root growth continues while top growth slows, and plants go into winter already anchored and ready to grow away the following spring.
A plant put in during autumn has months to establish its roots before the next summer tests it. One planted in late spring, by contrast, has only weeks before it has to cope with heat and drought while its root system is still shallow. That head start is why autumn planting tends to establish faster, need less watering and suffer fewer losses than planting done later in the year.
Autumn also opens the most cost-effective part of the planting calendar. From late autumn through winter, deciduous trees, hedging and many shrubs can be supplied bare-root or as rootballed stock, lifted from the field while dormant. This stock is lighter to handle, cheaper to buy and available in a wide range of species and sizes, which makes autumn the natural time to establish hedging and larger planting across a whole scheme.
Getting the benefit of the season depends on planning ahead. The best stock is spoken for early, and lifting, delivery and planting all have to line up in a relatively short window before hard winter weather. Decisions taken in late summer, on what to plant and when to have it delivered, are what secure the right material and the right slot when the season arrives.
What happens below ground in autumn
Roots keep growing later into the year than most people expect, with many hardy species making new roots through autumn and into early winter, and slowing only when soil temperatures drop below around 6°C. In much of the UK that threshold is not reached until well into the colder months, which leaves a long spell for a new plant to root out before winter proper sets in. That quiet underground establishment is the real basis for the season’s advantage.
A specimen in full leaf loses water through its foliage faster than a small, freshly disturbed root system can replace it, which is what makes summer planting so hard to keep alive. As the leaves fall and the days shorten that demand falls away, and a plant set out in autumn has far less to support above ground while its roots take hold.
The return of autumn and winter rain settles the soil around new roots and keeps it moist through the establishment period, which greatly reduces the need for irrigation. A plant that has grown roots into moist, workable soil through autumn and winter is far better placed to get through its first summer than one planted just before it.
The advantages over spring planting
Spring planting can work well, particularly for tender species and for stock held in containers, but it puts a new plant on a tighter schedule. The window between the ground warming and the arrival of summer heat is short, and any dry spell in that period falls on a plant that has not yet rooted out. Watering then becomes essential, and on a large or exposed site that is a significant and sometimes unreliable commitment.
Autumn planting spreads that risk by moving most of the establishment into the cooler, wetter months, so the plant reaches summer with a working root system and a far better chance of coping with heat unaided. For hardy, open-ground stock in particular, the result is usually faster establishment, lower watering costs and fewer replacements.
Autumn planting also takes pressure off the busy spring period and spreads a project’s workload, which can matter as much on a large scheme as the horticulture itself.
Bare-root and rootball season
The dormant season, roughly from November to March, is when field-grown deciduous trees, hedging and shrubs can be lifted and supplied without a container. Bare-root plants are sold with their roots clean and exposed, while rootballed stock is lifted with a ball of soil held in hessian, and both rely on the plant being dormant, which is why the season is fixed to the colder months.
For hedging and larger planting this is the most economical route by some distance. Bare-root whips and rootballed hedging cost far less than the container-grown equivalent, establish well in cool, moist soil, and come in a wide choice of native and ornamental species. A new hedge line, a group of standards or a whole structure of trees can go in during this window at a fraction of the cost of planting the same stock in leaf later in the year.
What suits autumn planting
Most hardy deciduous trees and shrubs are well suited to autumn planting, as are native and deciduous hedging, ornamental grasses and many herbaceous perennials that can be divided and replanted as they die back. Evergreens are best planted early in the season, in September or October, so they can settle before winter, since they keep transpiring through the colder months and are more exposed to cold drying winds than bare deciduous stock.
Very wet or heavy ground, and cold exposed sites, call for more judgement. Where soil lies wet through winter, planting is better held until conditions improve, since roots sitting in cold, saturated ground tend to rot rather than grow. On the whole, though, the great majority of hardy planting in the UK establishes better going in during autumn than at any other time of year.
Planning and ordering ahead
Good-quality stock, particularly semi-mature trees and specific hedging species, is ordered months ahead, and the best material is committed early, so the scale of the season’s advantage is only captured by planning for it. Confirming species, sizes and quantities in late summer is the surest way to secure what a scheme actually needs rather than settling for what is left.
Clearing weeds, relieving compaction and improving the soil before stock arrives lets planting go ahead as soon as conditions and deliveries allow, without losing days of the window to site works. On larger projects, agreeing a delivery and planting programme in advance keeps the lifting, transport and planting in step through what is a busy period for growers and contractors alike.
The autumn planting window is short, but it is the most productive stretch of the year for getting new planting established. Plants set into warm, moist soil as the season turns grow roots through the cooler months, and those roots carry them through their first summer, so a scheme planned and ordered ahead of the rush is the one most likely to make the most of it.
For more information about autumn planting and securing stock for your project, speak to the G Team today.