Landscape gardener and Life columnist Justin answers your questions.
I have a blueberry shrub which is five years old . Every year it profusely produces flowers and comes into fruit, but the fruits do not grow big and fall off the shrub. I have fertilised it with acid fertiliser and sheep pellets and watered it well and this year I pruned it. Please tell me what I should do to get mature fruit.
- Pari Bartlett
Make sure you have a the right variety for your conditions. Blueberries as a rule prefer a colder climate but the rabbiteye varieties are less fussy and are available from King's. I would also stop feeding your shrub as flower or fruit drop can be the result of over-fertilising. Plant your blueberries in free-draining, acidic soil with full sun, and mulch with leaf mould, which will mimic the conditions of its natural environment. Cutting back your plant may have a beneficial effect in the long term as your plant will produce new shoots. However, the fruit grows on the second year wood and beyond so try to remove only dead or diseased branches.
We have found an effective way of ridding our garden of oxalis that we thought we'd share with your readers. Pour a jug of just-boiled water on to the base cluster - the heat travels down the stalks and destroys the tiny bulbs deep in the soil. If the plant is flowering, we pluck those and dispose of them in the rubbish.
Occasionally a repeat treatment is needed the following year.
- Margaret and Mike Karetai
Thank you Margaret and Mike - boiling water and steam are often used to control weeds effectively. Many city councils use steam instead of spray to tidy up their verges, and one of the oldest tricks in the book is using boiling water to get rid of those annoying weeds between the cracks in pavers. I will now try it myself with the dreaded oxalis.
I'm guessing the limitation will be if it is growing through beds of desirable plants. In this case, you'd need to be careful where you poured the hot water.
I have a citrus tree I bought about five years ago. It flowers and grows small buds of fruit, but they soon fall off. The plant seems healthy - its leaves are dark green - and I've loosened the soil at the roots and topped it up with sheep pellets and compost, but there's been no improvement. There are currently about 15 small fruits on the tree, but they've stopped growing.
- Andrew Cabral
There are many reasons why citrus drop their flowers and early fruit. Firstly, it's a natural condition of the plant to shed fruit after a prolific flowering and fruit set. Without this self-pruning process, many citrus varieties would not be able to bring full-size fruit to bear. I have also found that varieties of citrus which are more suited to warmer climates, such as the Tahitian lime, are more susceptible to flower and fruit drop, so make sure that these varieties have excellent all-day sun. Try planting them next to a north-facing wall. If possible, keep these varieties pruned in a way that allows good air circulation. This radically reduces the occurrence of bacteria and fungal infection. Try not to prune the tips of the branches as this encourages the tree to bush out. Instead, thin the tree from the inside out, and allow more room for air and light around the fruit.
Other possible reasons for your problem include wet feet, which a lot of citrus hate, or a lack of trace elements, especially magnesium, which is not available in compost or sheep pellets. In this instance, a quick fix would be Sequestrone Plant Tonic from King's. Eliminate mites and white fly by using Yates Conqueror Oil or an organic alternative.
I planted a crab apple in a Japanese-style courtyard that does not get much sun (late morning to early afternoon, only). It gets the occasional feed of compost, and a bit of water. Last summer we had very little blossom, a few buds and no fruit. Do crab apples sulk if it is too shady? Should I replace it with something that doesn't mind low light, and if so, what could you suggest that is Japanesey and changes with the seasons?
- Katy B of Birkenhead
The crab apple does not do well in heavy soil (which is generally the soil type in Birkenhead) and requires a decent amount of sunlight to reach its full potential. Maintenance in this situation can be an important factor. Feeding, watering and pruning all help a tree reach its best in an atypical environment, however there are alternatives to give you that Japanese look which may suit the conditions more - a flowering cherry or plum (try "Thunder Cloud"), Michelia yunnanensis or Magnolia "Star Wars".
An outside option that would be a lot less fuss but will increase your pruning programme would be Robinia pseudoacacia. This deciduous tree might not have the amazing flowers of the crab apple but in summer it will provide beautiful, translucent, dappled light to shade under.
* It's flower time - load up on potting mix and seed-raising trays.
* Plant lots of flowers. Flowers create diversity which improves your garden's resilience to pests. By attracting beneficial insects, flowers will help keep predators from attacking your other plants.
* It's your last chance to move any trees and shrubs.
* Compost around strawberries and mulch with straw.
* Sow coriander before the weather gets too hot.
* Sow onions, potatoes, peas, broad beans, radishes, carrots, beetroot, and fast-maturing cabbage like Early Jersey Wakefield from the Koanga Gardens' seed range.
* Green crop any fallow ground or disused planter boxes with lupins.
* Clean out fish ponds and water features.
* Turn your compost again. This will speed up the process and it won't be long before you'll be in need of this black magic.
* Remove potted plants from pots, trim roots and re-pot with fresh potting soil into the same pot or a nice new one.
* Get your herb garden ready. This is a particularly good idea for first-time gardeners starting off with marginal or clay soil.
* Get your sun hat and sun lotion ready for warmer weather.
For more gardening tips see kings.co.nz
* To ask Justin a question, click on the email link below.By Justin Newcombe Email Justin