Gardening: Timely rainfall as planting season well under way

Gareth Carter of the Springvale Garden Centre and Chronicle gardening writer carries out a Christmas tree for a customer.

Last weekend we experienced some great rain for the garden. Some parts of the country have had too much rain with some serious flooding the result. Here in Whanganui we have had a good amount, topping up our gardens that were starting to dry out.

This timely rain fall has now extended the active planting season - plants grow and perform well in the heat. Keep vigilant monitoring moisture levels however, as with consistently warm temperatures it will be necessary to give some extra H2O to your plants again soon.

When you do, make sure you water in the early morning and evening to avoid scorching your plants. We are lucky in Whanganui to have a good water supply without restrictions. The golden rule to watering is to water less often, but to water more deeply; this will encourage roots to go further down, giving them more resilience in dry spells.

Light watering on the surface every day has the opposite effect. For most gardens, a couple of times a week for a long period is better than every evening for a short time.

Another way to keep plants strong during dry periods is the practice of mulching.

Bagged products such as "Natural Bark Feeding Mulch" are very effective. It is a bark-based much mixture of poultry compost and gypsum, with added hydraflo (water retention). This product is designed to fertilise, improve soil structure and retain moisture.

Barley or Pea Straw Bales. These are great in the garden. Laying a thick layer of newspaper or some cardboard on the garden then covering this with straw will give weed suppression for 9-12 months. It will aid water retention increasing soil moisture levels and it will improve soil fertility and structure as it breaks down.

Watering and mulching your garden will give the plants in your garden health and resilience ensuring that plant growth continues at a rapid rate.

Roses in flower are looking absolutely stunning in the gardens of many homes at present around the city and summer annuals planted during September and October are starting to look a real picture.

Rose Matawhero Magic

You can still plant out summer bedding (flowering) plants and create a colourful and magnificent show. Petunias, marigolds, verbena and gazanias are popular for hot sunny spots and impatiens, begonia and lobelia will grow where there is shade.

Garden borders, containers and hanging baskets can be rejuvenated. Remove weeds and fork in liberal amounts of compost and fertiliser into garden plots as preparation for planting.

Mulch roses and other shrubs to help conserve soil moisture as conditions dry plants out. Hanging baskets and containers have a better chance of surviving summer if they are filled with potting mixes that have storage and re-wetting granules and controlled slow release fertiliser added.

In addition feed every 10-14 days with liquid fertiliser such as Ican Fast Food. Please read container labels carefully and follow directions given. It is time to stake herbaceous and perennial plants as they are getting taller and tie in climbing plants to their supports or frames. Otherwise winds can result in whole branches snapping off.

The warm temperatures that are promoting good growth in the garden are also resulting in a rapidly expanding population of aphids, whitefly, caterpillars, scale, potato/tomato psyllid and other attacking insects.

A good "bee-friendly" insect spray is Yates Mavrik. This spray works on contact with the insect. This means that to break the life cycle of an infestation a few sprays in quick succession will be needed to knock back the population. Follow all packet directions carefully when spraying pests and diseases, care should be taken so that the spray reaches both sides of the leaves to get an effective result. An organic product, Naturally Neem, can be used for aphid, whitefly, thrip and mealy bug.

I have recently read of a recommendation of mixing these two products to good effect. Mavrik works by contact and ingestion, while Naturally Neem stops feeding and disrupts the breeding cycle. A mixture of Yates Mavrik with Naturally Neem offers a two-pronged attack giving particularly effective results.

This combo works on all chewing and sucking insects. Once the spray is dry, it is bee-safe. It can be used on vegetables and has a three-day withholding period.

Combat 3 in One for Roses is a good rose spray. Combat is the only three in one - insecticide, fungicide and fertiliser especially for Roses. Combat is marketed as a Rose Spray but is also suitable for other ornamental plants. This weather has been great for the bugs - beat them to the draw with Combat!

Christmas Trees

Some of you will be obtaining a cut pine tree to decorate as your Christmas Tree. To preserve your tree from drying out too quickly you can spray it (outside) before you decorate with Vaporguard, an organic anti-transpirant spray for plants.

This product has numerous uses including reducing transplant stress on seedlings and as a sun screen for plants. It is useful for moisture retention in hanging basket plants and as a leaf polish on pot plants and ornamentals. It is also useful in reducing wind and salt burn damage.

Hydrangeas

Hydrangeas are star performers in the summer garden. The most familiar are hybrids of H. macrophylla which means long or large leaves. The bold heads bloom in white, pink, red and blue in summer. Although many are seen existing with little or no attention, they do respond to pruning and feeding.

Colours can be controlled and intensified and blooms greatly enlarged. Fortnightly liquid feeding now during the growth period after the flowers have formed will encourage enormous sized flower heads. Hydrangeas vary in flower colour according to soil acidity or alkalinity.

Blue colours may be retained with aluminum sulphate applied at 2-3 week intervals on and red and pink colours are retained with applications of garden lime. These pH adjusting products are available in the garden centre in both liquid and powder forms.

House Plants

Most houseplants should be repotted by now. If you have not done this yet, it should be given some urgency so that your plants grow well this summer. Use a fresh new potting mix with long-term fertiliser and wetting agent added. Apply a supplementary soluble houseplant feed every 2–4 weeks during the growth season. Ican Fast Food is popular for this. If your houseplants don't require repotting apply slow release fertiliser such as Osmocote or ICan Slow Food.

• Gareth Carter is General Manager of Springvale Garden Centre