From the Potting Shed, with Chris Milborne

From the potting shed...

Our monthly gardening newsletter, written by our Great Amwell plant department colleague, Chris Milborne.

November 2024

November days are becoming visibly shorter and cooler and damper weather conditions prevail. So far this autumn we have had higher than average rainfall by a significant margin but also enjoyed a few magnificent days with temperatures above average for the time of year. Late autumn flowers looked superb, plenty of vegetables available after a very slow start and the soil, unlike some previous years, is perfect for soil cultivation and especially for planting spring flowering bulls.

Nowadays in November, leaves reach their peak of autumn colour which is over all too soon with the wind and rain. The leaves come cascading down putting an end to the final colourful displays, so now is the time for winter-coloured stems and bark and evergreen plants to come into their own. Many evergreens have interesting leaf shapes and colours from many shades of green to golden variegated colours. Some have attractive flowers and some are winter-flowering. The flowers are highly scented because they need to attract the winter pollinating insects as they are fewer in number at this time of the year.

This is also the time for berries and fruits - an important food source for winter wildlife. Crab apple fruits are superb this year and as the fruit ripens it turns into glorious shades of golds, reds, oranges and pinks. The fruit is good for making into jellies or leave them on the tree for winter birds to feed on. Crab Apple trees are an ideal specimen tree, suitable for smaller gardens.

A group of plants, perhaps now out of fashion, that are very important for wither interest and that have a wide range of uses, are the conifers. Conifers belong to an ancient group of plants dating back some 300 million years and many of today's plants seen can be found in fossils that formed some 60 - 120 million years ago. They provide a range of winter foliage colours such as yellows, steely blue, blue-greens, coppery yellow like Thuja Rheingold and the reds of Cryptomeria Japonica.

There are four types of conifers that are deciduous trees which are brilliant for Autumn tints. These include; Maidenhair trees, Dawn Redwood, Larch and Swamp Cypress. Conifers have a wide range of growth habit and sizes - dwarf for rockeries, compact for mixed borders and tall trees as a specimen for large gardens.  The tall, thin columns of Cuppressus Totem and dwarf pines can bring the feel of a Mediterranean garden when used with lavenders, cistus and grasses etc in a gravel garden.

The foliage of many conifers is aromatic as the scented resin protects trees from insect damage or fungal infections. The leaves are long and thin and others have scale-like leaves. They are often very dark shades of green as this is better for growing in areas of weak sunlight or forests and are an important plant for carbon capture.

Winter conifers provide a colourful contrast to the bare stems of Dogwoods, willows and ornamental rubus. Conifers can be pruned and shaped by raising the crown of the plant or some conifers look spectacular when "cloud pruned" (cloud shaped foliage) at the end of branches also reveals interesting bark. Use strongly shaped conifers such as conical Picea Glauca Albertiana Conica or mound forming Chamaecyparis, Green Globe.  ‘Fastigiata’ yew makes an excellent clipped topiary and is easy to grow - a great alternative to Box or Bay trees.

A conifer that always fascinates is the Monkey Puzzle Araucaria Araucana with its thick triangular and sharply pointed leaves. It is native to central and southern Chile and is now endangered due to land clearance and farming. One way the early plant hunters collected seed was by shooting down the seed cones. Once introduced to the UK the plants were much in demand, popular in Victorian and Edwardian times and widely grown in parks and gardens. Many seen today were planted during this period. Conifers are also useful for creating your own Bonsai collection. With careful shaping, pruning and training you can produce wonderful trees in miniature.

As herbaceous perennials start to fade and die back, leave any with seed heads to provide winter feed for the birds. I prefer not to cut back any old stems until next spring as these provide insulation and protection for next year’s dormant buds and new growth that are just below the soil surface. I do however, remove any wet, soggy leaves that could cause the crown of plants to rot and perhaps cut back any plants that may need some sort of support.

Hedging

November is the traditional time to plant hedges. They look more natural than fencing, provide privacy, can act as a windbreak and can be used to screen off parts of the garden. Hedging can be clipped into formal or informal shapes with arching branches covered in spring or summer with flowers or perhaps mixed planting with evergreens and deciduous plants. Perhaps try adding roses for their colour and fragrance or Philadelphus with clusters of creamy white scented flowers in June and July.

Evergreens are ideal for dense, green hedging throughout the winter. For leaf interest plant Eleagnus X Ebbinge with its silver bronze foliage and the bright golden variegated leaves of Eleagnus Pungens Maculata. New leaf growth of Photinias provides bright splashes of red too. Japanese Holly (Ilex Crenata) is similar to Box in leaf shape and habit but without the problem of Box caterpillar and blight.

Privet (Ligustrum) with its several different leaf colours and Laurel (Prunus Lusitanica) are also good for creating hedges. They are suitable for creating a low growing, decorative plant to divide different parts of your garden. Other plants to consider are Lavender Hidcote - a dwarf plant growing to approximately 60cm in height and spread. It needs a sunny position in well-drained soil. For an informal look try Cotoneaster Lacteus that has glossy dark green foliage and clusters of small white flowers in spring and attractive red berries in late summer and autumn. Berberis is a large group of plants, some evergreen, others deciduous. All have orange or yellow flowers and attractive foliage.

Chaenomeles is an ornamental Japanese Quince with beautiful cup-shaped flowers in whites, reds and pinks and has scented autumn fruits. Forsythias have a mass of yellow flowers that bloom from March and April. Mixed hedging looks wonderful and is good for attracting birds and pollinating insects into the garden.

Plant for glorious spring colours.

The cooler conditions of November make it the ideal time for planting Tulips whether in tubs and containers or in borders. Tulips are large and showy and available in a wide range of colours such as orange, scarlet and yellow or softer pastel shades of whites and bicolour.  Tulips look superb planted amongst forget-me-nots, Pansies, Violas, Primroses, Polyanthus and Wall Flowers - all provide a traditional planting scheme.

When selecting bulbs think about colours, height and precise flowering times. The tulip usually provides about three weeks of colour so select early, midseason and late varieties for continuous colour from March to the end of May, although even with careful planning, nature will affect the exact flowering time.

With containers, plant 2 layers known as ‘lasagne planting’ with the top layer at least 10cm below the soil surface and use one variety per tub for impact. Bright colours and white stand out better in the late winter or early spring gloomy weather. Plant smaller species of tulips amongst Alpines in the ground or in containers.

Plant Amaryllis bulbs from late October onwards. This plant originates from tropical South America. Use a pot slightly larger than the bulb - personally I use terracotta pots for better stability. When planting leave the top third of the bulb uncovered and keep the compost just damp until actively growing. It does best on a warm, bright windowsill at a temperature of 18-22℃. The flowers are stunning!

Dahlias, after a slow start and battling against slugs, have given us a fantastic show of colour all summer but now is the time to lift and store Dahlia tubers. Personally, I have found that if left in the ground over the winter, especially with the wetter conditions or in clay soil, the cold and wet can rot the tubers. Many found newly planted tubers rotted before starting to grow due to this year’s damp spring weather. For next year, start the tubers off in pots and grow them on in a frost-free greenhouse or cold frame and then plant out after the last frost when actively growing. Also, the larger, stronger plants are less prone to slug and snail damage.  

When lifting Dahlia tubers cut back the stems carefully and leave them to dry for a couple of hours as this helps to harden the skin. After giving them a thorough clean store the tubers in a frost-free shed on garage. The tubers need to be placed with the hollow stem facing downwards so any moisture drains out rather than rotting tubers and surround them will straw dry leaves, dry compost or sand. I regularly inspect them monthly over winter to check for any signs of rot.

Prepare for winter

Raise containers onto pot feet to help prevent waterlogging as this allows for better drainage than pots sitting in water.

Mulching helps to replenish the soil especially with recent wet weather leaching out goodness from the soil. Mulching also helps to protect plants such as Agapanthus from the cold weather conditions, protecting the roots and suppressing weeds. With the recent mild weather, weeds keep growing! I leave fallen leaves on beds and borders to rot down.

Put out bird, feed and provide fresh water. If emptying or turning compost heaps, watch out for over-wintering amphibians. I recently found slow worms in the allotment compost heap.

Prepare your garden for winter and check for anything likely to be affected by the cold, wind or water logging. With the good soil conditions, it is an excellent time to plant trees and shrubs plus the new seasons roses which are now available.

November is traditionally a good time of year to plant our soft fruit such as, blackcurrants, gooseberries, white and red currants, raspberry canes and blueberries. Tidy the strawberry plants by removing any dead leaves and runners. Start pruning Apple and Pear trees between now and February. Put grease or glue bands round the trunks of fruit trees as this prevents female winter moths from climbing the stems and laying eggs in the bark crevices on branches.

Prune your roses by a third to prevent ‘wind rock' that can destabilise the plant and loosens the root system. Prune back by a further third next spring. When replanting tubs and containers, use the old compost as a mulch on beds and borders.

November plant highlights

• Arbutus Unedo the Strawberry tree, is a compact, slow-growing shrub or small tree with interesting reddish brown bark and produces clusters of white bell-shaped flowers followed by fruit, supposedly looking similar to strawberries.
• Fatsia Japonica is an architectural looking evergreen with large hand-shaped leaves and in late autumn it produces clusters of creamy white fluffy flowers.
• Skimmia Japonica ‘Rubella’ the male form of Skimmia, produces clusters of pale pink buds that open out to produce scented white flowers in the spring. This plant thrives a well-drained, lime free soil. It will benefit from adding organic compost added to the soil and plant in a sunny or lightly shaded area. Other Skimmias such as Veitchii or Foremanii, are a female form that produces red berries.
• Viburnum Davidii is a small evergreen shrub with strong, ribbed oval foliage producing turquoise blue berries in autumn and winter and is a plant that grows well in sun or light shade and in well-drained soil.
• Erica Carnea or winter flowering heather is a dwarf, shrubby plant that keeps flowering even in cold, wet, windy conditions. Plant in containers with Nandinias, Hellebores Heucharas, Conifers and Ivy for a winter interest display.
• Lonicera Henryi Copper Beauty is an evergreen honeysuckle with bronze new growth in spring and fragrant, coppery-yellow flowers in late spring and early summer.
• Clematis Urophylla Winter Beauty has dark green, evergreen foliage with interesting small white ball-shaped flowers from December to March.
• Myrtus Communis is an evergreen shrub with aromatic leaves and clusters of white flowers in the summer easily grown.
• Potted Topiary is great for providing interest on the patio or by the front door or even filling a gap in the garden.

Watering Reminder

Potted containers, especially potted evergreen topiary and conifers will need checking to see if they need watering as although the weather can be wet, due to the 'umbrella effect’, the water can cascade over the edge of tubs and containers and doesn't always reach the roots. Even over the winter months, potted containers will need monthly feeding - Tomato Feed works well.

Houseplants

If the weather is damp, cold and wet, indoor gardening and houseplants become more important and over recent years houseplants have become increasingly more popular. The secret to growing houseplants successfully is providing the exact conditions that each type requires. There is a right plant for every room in the home as every plant family requires different light levels, warmth and humidity.

Houseplants are available in a wide range of leaf shapes, textures, sizes and colour. Some produce amazing flowers such as the orchid family and Bromeliads and they all improve air quality.  Spathiphyllums are perhaps the best at this.

Palms

One of the most popular and easy to grow houseplants is the Palm. With its architectural foliage it gives a tropical feel in all settings whether traditional or in contemporary designs and in offices. One of the popular palms is Chameodorea Elegans originating from the rain forests of Southern Mexico. The name comes from the Greek word meaning ‘gifts’ due to its easy-to-reach fruits in its native habitat. It is easy to care for in indirect light but avoid hot summer sun through glass windows and in dry conditions stand the plant on a tray of damp pebbles to increase humidity.

Palms need feeding ever 2 weeks in summer and once a month during the winter. Don't position them near radiators or in a cold draughty spot and maintain a minimum temperature of 10-13 degrees C.

Kentia Palms are a majestic palm endemic to the Lord Howe Islands off the East coast of Australia that were discovered by a horticulturist on the James Cook second voyage to the Pacific in the 1770's at the same time as the Norfolk Island Pine. The Norfolk island Pine (Araucaria Heterophylla) is another architectural, attractive, interesting and easy plant to grow. Kentia Palms with their arching, feathery, green leaves were very popular in Victorian times and are easy to care for. They like bright, indirect light and water from the top and keep the compost slightly damp in winter and feed monthly. In the spring and summer increase watering and feeding.

Araucaria Heterophylla is another interesting, attractive and easy plant to grow.

Depending on space available, houseplants can be purchased in a wide range of pot sizes, from plants grown in 5cm pots, suitable for growing in terrariums, up to large specimen plants such as Areca Palms, that were discovered by Herman Wendland in 1878 when travelling to Madagascar. This plant requires a bright position away from direct sunlight to prevent browning on its leaf tips and due to dry household conditions, give it a light misting or stand on a tray of damp pebbles.  I use moss raked from my lawn for a natural look.

Whatever the weather, make the most of the garden. If the weather allows, there’s still lots to do but if sheltering from the wet enjoy the beauty of houseplants.

Next month we are looking forward to the flowers and colours of Christmas houseplants and looking towards the New Year.