Tag Archives: Tikorangi: The Jury garden

The merits of mulch

Homemade compost - our preferred garden mulch

Homemade compost – our preferred garden mulch

Mulch, dear readers, mulch now. Mulch well and you will be grateful later.

There are good reasons to mulch. In areas prone to drying out over summer, a good layer of mulch put on now will contribute to retaining soil moisture levels later. You don’t want to be mulching when the soils have already dried out because, equally, it acts as a barrier to stop water being absorbed.

Mulching also keeps down weeds and hugely reduces the amount of summer weeding that is required. There are two provisos. You need to clear the area of weeds first. Mulch won’t kill existing weeds. It just discourages germination of all those seeds lurking in the soil waiting to spring forth when the time is right. It also makes it much easier to pull out those that do penetrate through the layer. The second proviso is that you need to be using a weed-free mulch and many home compost mixes won’t have achieved that state.

Avoiding soil splash is another benefit. In areas of heavy rainfall (and some of us can get downpours akin to the tropics, albeit without the warm temperatures), bare soil splashes back up and this can spread disease amongst vulnerable plants. Soil splash also makes vegetables dirty. Mulch acts as a cushioning filter.

Depending on your choice of mulch, it can act as a soil conditioner and add valuable carbon content. Some will gradually break down as worm and microbial action incorporated it into the soil. Obviously this is only true for organic matter. We are big fans of organic mulches here, less so of inorganic options like limestone chip or gravel. But no matter what you use, a mulched garden looks better than expanses of bare soil. It is the experienced gardener’s not-so-secret weapon. You won’t find many good gardeners who do not mulch regularly.

So what to mulch with? Our number one preferred option is compost, homemade compost in fact. It does three jobs in one hit. It mulches, it feeds the soil so that we rarely have to use other fertilisers and it looks unobtrusive. But then we do not want a mulch that looks obvious. It is a tool, not a display in itself.

Leaf litter can be untidy but makes a good mulch

Leaf litter can be untidy but makes a good mulch

The second choice mulch here is leaf litter. We don’t waste any organic material. If it doesn’t get composted, then it gets raked into a back area to gently decompose and darken, before being raked back out around plants. Leaf litter can be untidy but it is good in less formal areas.

Then there is fresh wood chip. We own a good sized mulcher so we generate a fair amount of wood chip from the garden debris that is too large to go into compost. Calf shed shavings and sawdust also come into this category. When fresh, all these materials have to be used as mulch but not dug into the soil or they will rob the nitrogen as they break down. Laid on top and exposed to the elements, the decomposition happens slowly and naturally and should not cause problems. If you are going to use sawdust, just make sure that it is never, ever tanalised (you will poison your soils) and be prepared for a few months of a somewhat alarming orange appearance.

Old wool carpet and newspaper (weight the latter down) can be used as mulch if you don’t mind the look. We do mind, so we don’t go down that track. Just make sure the carpet is 100% wool and not synthetic and keep to newspaper – leave the glossies out with the recycling.

Pea straw may be a better option for the vegetable garden than the ornamental garden

Pea straw may be a better option for the vegetable garden than the ornamental garden

If you need to head off to the garden centre to buy your mulch, you will often find pea straw on offer. While this is a traditional mulch, if you are not in a pea producing area, consider its carbon footprint. It blows away unless you keep it damp. It is a myth that it helps fix nitrogen in the soil – that capacity is in the pea roots and all you are buying are the tops. Aesthetically, I think it looks fine in the vegetable garden (especially if it is all around high-producing strawberry plants) but I am less keen on the look in ornamental gardens. A bale should cover around 6 square metres of area.

Granulated pine bark is often favoured. Try and get it pre-composted. Compounds in the bark stop it rotting down too quickly so it lasts a surprisingly long time on top. It is a discreet looking mulch but it adds no fertility. If you have a big area to cover, buying it in bulk will save money. A cubic metre should cover around 15 square metres.

You need a layer of 6 to 7 centimetres to be effective. You will often see 10 cm recommended but that is pretty deep. Finally, try not to pile the mulch hard in on the trunks of woody plants. It doesn’t matter around perennials but trees and shrubs run the risk of collar rot.

The mulching effort now will reward you further down the track.

First published in the Waikato Times and reprinted here with their permission.

Garden lore

“Hoeing: A manual method of severing roots from stems of newly planted flowers and vegetables.”

Henry Beard, American humorist.

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I am a big Wonder Weeder fan. These are the best implements I know for hand weeding, especially in tight spaces. Because the action is to hook out the weeds, it is possible to do it with minimum of disturbance to surrounding plants. It still amazes me that something so simple, indestructible and effective has remained cheap. I own several because they regularly end up going through the compost heap. I have no commercial interest in these but I see you can buy them on line – three for $15 (including delivery) at wonderweeder.co.nz and some garden centres sell them.

Others swear by the Niwashi which is probably somewhat more expensive and less happy about going through the compost. This is a small hand-held hoe. It severs the plants from its roots which will be enough to kill most, but not all, weeds. It is also better than a trowel for cultivating the soil in smaller areas. You need at least a 12cm space between your plants or you will sever them in the process.

For flat weeds in the lawn, or very deep rooted plants like dock, there is nothing to equal the lawn weeder which can hoick plants out, roots and all, in one simple move. If you don’t want a small armoury of specialist weeding implements, an old table knife does the trick once you have mastered the different hand actions required.

First published in the Waikato Times and reprinted here with their permission.

Plant Collector: Dendrobium Bardo Rose

Dendrobium Bardo Rose

Dendrobium Bardo Rose

Out there in the world are legions of orchid aficionados who are typically possessed of technical knowledge about this plant genus, the most complex and varied of all plant groups. I take one peek in to the details of orchids and get completely lost. But when it comes to orchids suitable for the garden, I can recommend the dendrobiums from Australia. There are many different dendrobium species. Some are tropical and only suitable for glasshouse culture here. But the obliging ‘Aussie dendrobes’, as we refer to them, sit happily in woodland conditions needing no care or attention at all. In early to mid spring, they spark into flower and this pink one has nigh on fifty flower spikes. The flowers are much smaller than cymbidiums and the whole clump only stands 30cm high at the most.

Bardo Rose is the grex name (more or less a collective noun) for all dendrobium hybrids which are falcorostrum x kingianum. We have both those species growing here as well but this pretty pink one is a hybrid between the two. Each flowering spike has 20 or more perfect little orchids which measure about 3cm x 3cm. Other dendrobiums we grow are in pure white (including the aforementioned D. falcorostrum) and shades of yellow.

I do not know if dendrobiums are sold commercially. All ours came from the Orchid Society who are renowned for their generosity. These folk will also be able to advise which ones are fully hardy – and some are. Critical issues in growing these plants include excellent drainage, good light levels but dry in winter so under evergreen trees seems to be a good location.

First published in the Waikato Times and reprinted here with their permission.

Garden lore

“I am very fond of the Spring-flowering colchicums, but unfortunately slugs are also, and those greedy gastropods and I have a race for who can see the flower-buds first. If I win I go out after dark with an acetylene lamp and a hatpin and spear the little army of slugs making for a tea-party at the sign of the Colchicum.”

Edward Augustus Bowles My Garden in Spring (1914)

Thrip infested leaves to the left, healthy to the right.

Thrip infested leaves to the left, healthy to the right.

Thrips galore

Clearly last summer’s drought stressed some plants more than we realised at the time. Thrips. We have thrip infestations on plants which do not normally suffer. Plants show the damage as silvering on the leaves. It is common in many rhododendrons but bay trees and photinia are also prone to infestations, along with other plants. You can’t turn the silver leaves green again. Turn over the leaf and you will see rusty looking spots behind. This is the residue of the thread-like thrips which suck the chlorophyll out of the foliage. The damage is done.

Prevention is better than a cure. A strong, healthy plant with plenty of air movement around it and good light levels is better able to withstand attack. There are systemic insecticides you can use which the plant absorbs into its system, killing the thrips from the inside out but you have to wait until the critters are active again – usually late November. The bands sold that you wrap around the trunk of the tree will either be soaked in systemic insecticide or in Neem oil. We have never tried Neem and are surprised if it works as a systemic, but others say it does.

Contact insecticides don’t work unless you can saturate the underside of every single leaf so most organic remedies won’t work. The fresh spring growth will hide a multitude of sins and we are hoping that the thrippy plants will look fine again. Some varieties are much worse affected and generally we choose to remove those and replace with better performing varieties because we do not want to have to use systemic insecticides just to keep plants healthy.

First published in the Waikato Times and reprinted here with their permission.

Low(ish) maintenance shade gardening

016 (2)It is clivia season here though it may not be clivia season for those who live in colder areas. Despite being much favoured by modern landscapers, these plants do not like more than a light touch of frost at most.

There are reasons why clivias are loved by landscapers. Of all the options for shady areas, they must be one of the most tolerant, forgiving and easy-care there is. For the better part of the year, they sit as a tidy clump of strappy foliage requiring little or no attention and when they flower in spring, the showy blooms last for many weeks. Plants can be left for years requiring no attention.

I looked at a photo of a property where the owners had used a reputable landscaper and the shady side of the house consisted of an access path with two narrow borders either side bounded by a solid fence. Both borders had been planted with clivias in single file, surrounded by bark chip as mulch. It is a very tidy, utility solution which, if the fence and path are smart, can even look stylish. If you like that sort of look.

Everything looks better with ferns, in my opinion. Ligularia reniformis.

Everything looks better with ferns, in my opinion. Ligularia reniformis.

Clivias are not a great choice for inland areas unless you are confident that you are frost free, which most of Hamilton and the Waikato won’t be. Sometimes such borders are beneath the eaves of the house and that will afford protection. But you will often see the same look achieved with, maybe, the tractor seat ligularia (L. reniformis), Ligularia ‘Desdemona’ or a similarly reliable, evergreen perennial.

It will come as no surprise to regular readers that it is not a look I favour, personally. While I can see the logic to keeping clean, crisp lines and some degree of simplicity, I just think it would look so much more interesting with the introduction of another one or two types of plants. They don’t have to be expensive or choice plants but what they add is textural interest, variation in height and sometimes the bonus of seasonal flowers.

Most gardens have a shaded area – at least that narrow side that runs alongside the bathroom and laundry and is on the other side from the sunny living areas. If it is a little-used area which is primarily access and has no house windows that look out to it, then it hardly warrants great expenditure of either money or ongoing effort. But a small amount of effort can make it so much more attractive and the beauty of shade gardening is that it tends to be much lower maintenance.

left to right: Helleborus x sternii, Francoa ramosa, pulmonaria, arthropodium (renga renga), phlomis, random fern and mondo grass - all cheap, reliable options for low maintenance shade gardening

left to right: Helleborus x sternii, Francoa ramosa, pulmonaria, arthropodium (renga renga), phlomis, random fern and mondo grass – all cheap, reliable options for low maintenance shade gardening

I headed out to the garden to look for options to add interest to a shade garden. There are plenty to choose from – just don’t choose them all if you want a clean look. Keep it to a maximum of three. Ferns. Pretty much everything looks better with ferns in the shade. They add a lightness of texture and detail of leaf to solid plants like clivias or ligularias and it is that contrast that can add interest.

Renga renga lilies are happy in more shaded areas and have the bonus of spring flowers. We have a lot of success with phlomis (P. russeliana or Turkish sage) with its yellow tiered flowers in summer. Similarly, the bridal wreath flower – particularly Francoa ramosa – is easy and obliging with summer flowers. The unattractively named lungworts or pulmonaria family combine very well with bigger, chunkier foliaged plants and add detail with their gentle variegation. Even common old mondo grass, be it black or green, can add a different texture. Helleborus x sternii is a reliable shade option with lime green flowers in winter.

If you keep to evergreen perennials which don’t require much more than an annual clean-up and which can be kept for several years without having to dig and divide them, you can make a low maintenance shade garden. Take care to plant them well in soil you have dug over, add plenty of humus or compost, mulch after planting and generally they can look after themselves.

It does not have to be expensive or difficult. If you can get simple combinations that are compatible, look good together, are happy in the conditions and meet the requirements of the gardener, it is a great deal more interesting than looking at a single plant variety en masse.

But that is the voice of a gardener, not that of a landscaper.

First published in the Waikato Times and reprinted here with their permission.