- If you are making only one New Year’s gardening resolution, for long term gains resolve not to let weeds go to seed. Long term it is labour saving. The light rains this week will have given enough moisture to start the next round germinating. Get them early with the push hoe. If you have ignored the last round and they are setting seed now, weed with a bucket at your side or you will be spreading the seed. Unless your compost heap generates high temperatures (and the black plastic types rot the contents, rather than sterilising by heat), keep seed heads out of the compost. You can either put them out in the rubbish (hopefully they get buried so deep in landfill that they can not germinate there) or if you don’t have rubbish collection, putting them in a black plastic rubbish bag in full sun should work.
- Do not delay on dividing the autumn flowering bulbs which will be triggered into growth soon. These include nerines, belladonnas, colchicums (often called the autumn crocus), most ornamental oxalis and cyclamen hederafolium. The rejuvenated clumps will reward you soon enough.
- Flowering cherries are summer pruned to avoid the effect of silver blight. If you have a tree with witches broom, you will have noticed in spring that you had sections which did not flower and where the foliage was much denser and came while the rest of the tree was flowering. Cut out the witches broom before it takes over the entire tree (which it will over time) because then you will have to cut out everything.
- If you had a problem with silver leaves on rhododendrons last year, check for fresh infestations now by looking underneath the leaves. The problem is leaf sucking thrips. The adult thrips are black and thread-like while the youthful offspring are white. The usual approach is to blast them with a systemic insecticide which the plant sucks into its circulation system. If you are not at all keen on this approach, cut out weak and badly infested plants (the damage won’t be showing in the new leaves yet but it will happen), and open up around other plants to increase air movement. Theoretically, an oil spray will suffocate the little critters and you can use a mix of light cooking oil with a squirt of detergent mixed with warm water. However, the problem is that you have to spray directly onto the underside of all leaves because it will only suffocate on contact so this is only practical where you have a very small number of plants. We haven’t tried them but apparently the collars of insecticide wrapped around the trunk can work well. The DIY approach is to secure a band of carpet around the trunk and then inject the concentrated systemic insecticide into the carpet. Wear gloves.
- Garlic can be harvested when you think it has reached a good size. Lift it and leave it on the ground while the foliage dies off. After being given a large bulb of smoked garlic at Christmas, we are keen to try smoking some of this year’s crop to see if it extends its shelf life through the season. Garlic tends to lose its oomph after about six months. The smoked garlic is wonderful for aioli and summer dressings.
- Unlike garlic, you have to wait for the tops of onions to bend over and start to wither before lifting the crop.
- Keep successional sowings of sweet corn, lettuce, salad veg and beans going and in a warm spot, you can plant a late crop of tomatoes.
Tag Archives: thrips on rhododendrons
November 13, 2009 In the Garden
- We are starting to dry out already. Keep a close eye on container plants. If they are showing signs of stress, it is likely they are either badly root bound (should have been potted on when we told you in winter), hungry or dried out. To get water back into dehydrated plants, a squirt of dishwashing detergent or surfactant will help absorption. However, ignore any advice given elsewhere to add water holding crystals (also called Crystal Rain) to potting mix for anything other than annuals. In our climate with high rainfall, woody plants and perennials will rot out in winter if you add these crystals, however tempting it may be in summer to use them. Partially burying pots and containers into the garden (called plunging) can reduce excessive drying out. It also stops pots with taller plants from blowing over in the wind.
- It is late in the season for planting out woody trees and shrubs, especially if they are large or root bound. Our advice is to heel them into the vegetable garden until autumn. If you are determined to plant into other garden positions, make sure that the root ball is soaked right through. A watering can just will not do. It can take hours (or leave overnight) to get the water into the middle if it is very dry. Once planted, mulch to conserve moisture and keep an eye on the plant until Christmas at least to ensure that it has not dried out again.
- If you spray for thrips on rhododendrons (the leaf sucking critters which cause silver leaves), get the first application on when you see the insects on the under side of the new growth. We are not keen on this practice and will only spray one or two special plants ourselves. We would be much happier to hear of gardeners opening up around the plant to encourage air movement, feeding and mulching to encourage more health and vigour and taking out plants which are particularly susceptible to replace with healthier selections. We have drawn a line under many of the cold loving German and American hybrids here and said that we just can not grow them well in our mild, coastal conditions.
- It is the optimum time for planting kumara runners. This is one plant which really loves warm, light soils.
- As soon as we get more rain, fungi are likely to attack potatoes and tomatoes. A copper spray applied as soon as the foliage has dried out after rain is usually necessary if you wish to guarantee a harvest later.
- Brassicas will be under siege shortly, if not already, from much of the insect population and in particular the dreaded cabbage white. This is the single biggest reason for not growing brassicas for summer harvest in our climate. If you don’t wish to spray with an insecticide, you have to start getting creative with old net curtains and the likes. However, this only stops the cabbage white laying more eggs and does nothing to deal to existing caterpillars in residence. We will be eating our remaining brassicas soon and not replanting until autumn, with the exception of brussel sprouts which are best sown in the summer for harvest next winter.
- Leeks can be sown now.
Tikorangi The Jury Garden 