Gareth Carter: The biggest weekend on the gardening calendar

Acer pixie hosta mouse ears hadspen blue. Photo Lachie Smith

This week has been a warmer week with temperatures rising above 20C each day. The timing is perfect as we have reached Labour weekend, the most famous weekend of the year in the gardening calendar.

It is recognised as the time when soil temperatures have risen to germinate warm season vegetable seeds such as beans and corn. Also that night temperatures should remain above 10C that the cucurbits (cucumbers, gherkins, pumpkins and many others) will actively grow.

Around the city some of the later flowering cherry varieties are now in bloom. My father's favourite 'Prunus shimidsu sakura' is at its best this week. Many rhododendrons too are looking amazing in full bloom.

The intensity of a blooming Rhododendron is impressive as the flower trusses hide the leaves and the stylish green structure becomes eclipsed by mass of colour.

Azalea mollis are in full flower now and many hostas are now through the soil. Pictured above is a stylish combination of Maple Pixie with Hosta Mouse Ears and Hosta Hadspen Blue. (photo and garden credit: Lachie Smith)

Vegetables

Now is the time to plant for a summer harvest of fresh, healthy vegetables for salads and other meals. Plan a programme of small successive sowings and plantings for a continuous harvest throughout the year.

Seeds to sow and plantings that can be made in Whanganui now include; bean, beetroot, broccoli, capsicum, carrot, celery, cabbage, cauliflower, cucumber, eggplant, lettuce, peas, potato, melons, spring onions, radish, rhubarb, silverbeet, squash, sweet corn, tomato, zucchini and more.

Hanging baskets

Now is the time to get your baskets planted for a stunning display for Christmas and summer. Growing hanging baskets is a wonderful way to garden and continues to gain wider popularity.

Today's lifestyle, often with emphasis on the full use of limited space has led to the acceptance of any means by which plants can be used.

Almost any plant that will grow in a container can be grown in a hanging basket, creating new visual perspectives even in a small courtyard, balcony or veranda. Luxuriant mini-gardens can be developed without taking up valuable ground or floor space. In cities around the world where people are living in confined spaces, hanging baskets and wall troughs are frequently used for growing vegetables, flowers and herbs.

Hanging baskets are often an answer to interior decorating problems. For example a basket containing a large green hanging fern will soften harsh walls or attractively fill an empty corner.

Flowering plants suitable for hanging baskets outdoors include; impatiens, marigold, nasturtium, ageratum, begonia, fuchsia, lobelia, nepeta (cat mint), pelargonium, petunia, portulaca, zinnia (dwarf) etc. Note that fuchsia are one of the finest flowering shrubs for a shady situation with stunning displays in Summer and Autumn. They have a magnificent affinity with hanging baskets and their branches will cascade over the side of the basket.

Perennials

Perennials are plants mostly with non-woody stems and branches that burst into growth in the spring and summer and many flower for long periods over the summer and autumn and die back to the roots or an evergreen crown for the winter season. They repeat this cycle year after year gradually increasing in size and number. There is a huge selection of perennials that can add interest and colour to the garden in summer and they come in all shapes and sizes. They often make a garden theme such as a cottage garden where they can be the companions for more permanent plants such as roses and trees. Herbaceous perennials such as hosta and astilbe emerge during spring, flower in summer and die down and become dormant in winter, they enjoy cool garden conditions. Perennials can complement many trees, shrubs, roses, annual flowers and bulbs. Many provide excellent flowers for indoor use. Others have attractive foliage in bronze, yellow-green, grey and silver.

Perennials prefer some good compost added to the soil with slow release general fertiliser like 'Novatec' when preparing to plant.

Prunus shimidsu sakura. Photo / supplied

Favourite perennials

Osteospermum

Also known as cape daisies these plants are hardy to conditions ranging from coastal wind and hot sun to semi-shady positions. They boast a continuous flowering habit with blooms almost year-round. They are drought tolerant and look great in containers and garden situations.

Geranium & pelargonium

These are ideal and easily maintained perennial plants for pots, window boxes and hanging baskets as well as in garden plots. They thrive in most soils in sunny positions. Regular pruning after flowering keeps the plants compact. Popular flower colours are red, white, pink and mauve. Ivy (climbing) geraniums have long stems for trailing over walls and fences or for trailing over banks. They are also suitable for hanging baskets. The Pac range are exceptionally good, the breeding programmes of these plants with exceptional ability to repeat flower with high intensity throughout most of the year while maintaining an attractive compact and bushy growth habit.

Heuchera

Grow well in full shade to half shade position, moist soils, approximately 30x45cm. They produce stunning foliage to add year round colour in gardens with clusters of small coral pink or white bells in spring and autumn. They love shade so are ideally planted under trees and shrubs or on the shady side of the house. Look out for varieties; 'Marmalade', 'Plum Cascade' and 'Plum Royale' – all stunning.

Hosta

Hosta grow well in full shade to semi-shade positions most in the 25-40cm range. They form handsome leaf colours and textures from bright chartreuse (yellow and green) through forest greens, icy blues and silver greys and cream or yellow variegated foliage forms. They have small, bell-shaped white or lilac flowers, sometimes fragrant in summer. They thrive in moist well-drained soils with plenty of compost added. Feed in the spring and mulch with compost, straw or similar to keep them cool and moist. Always be ready with slug and snail bait from early spring as they are often subject to voracious attacks.

Lavender

Lavenders are hardy flowering evergreen shrubs. The flowers of the English types are highly esteemed for their fragrance in a dry state and for distilling for perfume and oils, being grown commercially for the latter purposes. These versatile plants are popularly used as low hedges around garden borders, along driveways or grown as garden specimens or in pots. Most have attractive silver-grey aromatic foliage and lavender-blue flower spikes from spring through into summer. They enjoy a full sun to half sun position in well-drained soils.

Penstemon

These are a hardy bushy perennial. The tubular-flowering types have spikes of pink, mauve, white, blue and red flowers in late spring and summer. Grow in full sun position in garden borders or containers.

Tropical Impatiens

Also known as New Guinea Impatiens, these plants traditionally thrive in a shady, sheltered position. Recent breeding means we also now have a range of 'Sun Impatiens' which thrive in both sunny and shady locations. Where sites are frost free they will grow happily for a number of years. They provide magnificent colour throughout the summer and autumn months. They prefer rich, well-drained soil but are very adaptable. Tropical Impatiens grow well in pots making a colourful display.

• Gareth Carter is general manager of Springvale Garden Centre.