Do your roots need doing?
Those of you who joined the Tendershoots talk given by Andrew Mikolajski intriguingly entitled “Do your roots need doing?” (mentioned in our November Newsletter) will no doubt agree that it was a very interesting talk with many timely hints and tips. So, for those that missed the talk, there are a few I found helpful below.
In summary, there is a surge in root growth in Autumn making it a good time to:
get plants in the ground. (You can find some extra advice on good planting practice for healthy plants below) Land plants developed in association with mycorrhizal fungi and many sources recommend adding this when planting - bare root roses in particular. It is possible to make your own soil additive from plants which have mycorrhizal fungi naturally in their roots - lawn plantain for example. Dig up a plantain, cut off the thicker tap root & chop it finely. Mix with bonemeal (which feeds the fungus) and add to the planting hole.
lift & divide herbaceous perennials using two forks back-to-back, keeping the white (young & productive) roots and discarding the darker (older) roots.
take root cuttings of suitable plants. (See “How to take root cuttings” - 18 November 2021)
transplant trees and shrubs. To do this, cut a trench round the plant, cutting through the outer roots. Fill the trench with sand and leave it for a year before transplanting! Alternatively, if you want to move it straight away, undercut (i.e. dig round & under the root ball to cut through the outer roots) before lifting. Either way, the roots form callouses then produce new, more effective roots so the plant will romp away next spring.
root prune. Plants in containers, in particular, should be root-pruned every couple of years. Take the plant out of the container, get rid of the compost, trim the root ball by up to a third (so that you can replant in the same container if you wish) and replant with fresh compost. Cut through the outer roots to get the plant out of the pot if it is root bound. Trimming the roots is actually beneficial for the plant as it encourages the production of new fibrous feeder roots.
consider investing in Air Pots to grow robust plants! These air-prune the roots as they grow. The roots grow through the holes and die when they come into contact with the air, stimulating the production of a compact fibrous root system so that the plant is less susceptible to transplant shock when planted in the ground.
Andrew also advised on dealing with compacted surface tree roots. Essentially, if the tree looks healthy these are nothing to worry about. However, do not cut these roots away. If the tree looks sick, consider covering the roots with a shallow raised bed.
Perhaps the most interesting thing I learned was that, when plants such as dogwoods and hazels are coppiced, the root system partially dies, releasing nitrogen into the soil. So if you want to grow a plant that needs lots of nitrogen, plant it near a tree or shrub that you cut back hard annually. Clever eh?
Some good planting practices
Bare root roses. Soak overnight before planting. Dig a large hole and backfill with some soil then water and repeat soil/water, soil/water until the hole is filled. Bury the graft union 1” below soil level to achieve a stable plant. This also encourages dormant buds to shoot.
All roses. It is now widely accepted that rose-sick soil is a 'thing' rather than an urban myth; it is caused by pathogens in the soil. Old roses have some immunity to these pathogens, new cultivars less so. You can replace a rose that has died with a new rose but it's a good idea to plant it in a buried cardboard box filled with fresh soil. This gives the rose some protection from pathogens until it has built up its immunity.
Bare root trees. Autumn is the best time to plant these. Plant to the soil mark. Stake before starting to backfill.
Any plant. Put cardboard on top of the soil round the plant after planting, water it, then mulch. This suppresses competing weeds and retains moisture.
Clematis. Plant these deep. The stem will then produce roots resulting in robust plants.