The right soil for growing kiwifruit

Savvas Pastopoulos, Agronomist, Pastopoulos Agricultural Ltd

The same questions come up before every new kiwifruit planting. Will the block do? Is the soil too heavy? Will the borehole hold up in August? Is it worth spending money on earthworks and drainage, or is that wasted effort? The soil sets the limits, but it does not decide on its own. And there is one point that does not show on paper: blocks that looked marginal on paper have succeeded, provided their owner paid for it and goes on paying every year. This article explains where the limits are, what it costs to get past them, and when the answer really is no.

1. Why kiwifruit is so demanding about soil

This is not a quirk. It is anatomy. Kiwifruit combines three characteristics that no other fruit crop has together:

• The highest root density of any fruit crop, the roots are packed into a small volume of soil and compete with each other for the same oxygen.
• The smallest air store. The intercellular space of the roots, which acts as a “lung”, accounts for barely 2% of their volume, against 7% to 11% in peach and citrus rootstocks.
• The highest oxygen consumption. In saturated soil, all the available oxygen is used up within 5 hours [2].

These figures are developed in the article on kiwifruit vine decline syndrome, and they are the background to everything that follows. One thing is worth holding on to: “it needs drainage” does not simply mean that water should not stand. It means that the margin for error is measured in hours.

And the other side of it: kiwifruit is a water-loving species with high water requirements. It asks for a great deal of water and at the same time cannot tolerate water standing. That contradiction is the whole difficulty of the crop.

Sources: 2

2. The limits, in figures

The numerical limits that follow come from a University of California guide [1], that is from soils that are acid to neutral and distinctly less calcareous than Greek ones. Greek reference values for kiwifruit have not been published. The limits are used as a ranking of risk and cost, not as thresholds for excluding a field.

3. Soil texture: the most misunderstood criterion

A clarification is needed here, because the conversation has been simplified down to “it needs sandy soil”.

That is not quite right. The data show that kiwifruit performs better on loam and silt loam than on sandy loam [1]. Pure sands bring their own problems: no retention of water or nutrients, heavy nitrogen leaching, and nematodes, which in kiwifruit are a serious matter.

Acceptable limits by texture class

The percentages that follow are the limits of the USDA soil texture triangle, as any laboratory reports them on the analysis sheet. The suitability column applies specifically to kiwifruit.

The bulk density and infiltration limits are given as practical orientation indicators. Assessment of a particular block is always made by on-site evaluation and a full soil survey.

So the question is not “how much sand does it have” but “how fast does water leave the first sixty centimetres, and what happens at two metres”. That is answered by the hydrological assessment, not by the texture analysis on its own.

What a hydrological assessment is

The term sounds heavy, but in practice it is not some formal study with official stamps. It is a series of measurements in the field itself, answering one single question: where does the water go when it reaches the block, and how fast. The texture analysis says what the soil consists of. The hydrological assessment says how it behaves.

The difference is critical, because two fields with identical texture analyses can meet entirely different fates, if one has an impermeable layer at one metre and the other does not.

What is wanted is not a folder. It is a clear answer: the water leaves on its own, it leaves with engineering intervention, or it does not leave. In the third case, the question of cultivar and rootstock does not even arise.

4. Water, the criterion that rules out more blocks than the soil does

This is the point most often omitted, and it disqualifies more plantings than the soil itself. Kiwifruit is a salt-sensitive species: an increase in leaf chloride directly reduces the rate of photosynthesis [4]. The limits that follow are those of the Californian guide [1]; bicarbonates in particular are high in many Greek boreholes in calcareous areas, so exceeding the limit does not disqualify the field but makes acidification of the solution and monitoring of the emitters necessary.

Sources: 1 4

Beyond quality, quantity and reliability also count. Kiwifruit wants irrigation every two days in summer, and in a heatwave more often still. A borehole that runs short in August is not a management problem. It is a reason not to plant.

5. The three analyses before planting

Three analyses are needed before a new planting is established, not one:

1. Chemical soil analysis: pH, active calcium carbonate, organic matter, conductivity, nutrients, boron.
2. Physical: texture, bulk density, structure, degree of compaction.
3. Hydrological: this one is nearly always omitted, and this is the one that shows whether the block will do. Infiltration rate, position and seasonal variation of the water table, presence of impermeable layers in the profile.

And one job that is not an analysis but is worth as much as all three together: opening two or three trenches with an excavator, two metres deep, and examining the profile on site. Colours, layers, signs of hydromorphy, roots of the previous crop. Things become visible that no analysis produces, and the cost is minimal.

6. Dozens of factors beyond the soil

This has to be said plainly, because the article risks being read as though soil were the only criterion. It is not. Soil is a necessary but not a sufficient condition. There are perfect blocks with failed plantings, and the reverse.

The list is not exhaustive, and that is precisely the point. No table replaces an on-site assessment. Two blocks with identical analyses, one in a gully and the other in open ground exposed to the north wind, are not the same block.

7. Marginal blocks, what is actually needed

And now the substantive part, because most growers do not choose a block. they have a block.

The good news is documented. Kiwifruit performs excellently on first-class soils, but “good and occasionally excellent production is also achieved on second-class soils, provided management is correct” [1]. That is not consolation; it is an observation from regions with decades of experience.

What “correct management” means on a marginal block

• Ridges. Planting on raised rows lifts the root zone above the critical layer. It is the basic tool on heavy soils.
• Subsoil aeration and breaking of impermeable layers before planting, with deep ploughing or a subsoiler. It is done once, properly, with dry soil. After planting it is never done again.
• A drainage network. Open ditches or subsurface pipes with a clear outlet. Without an outlet, drainage is decorative.
• Organic matter, systematically and permanently. It is not a luxury: it acts directly on structure and on hydraulic conductivity. On a marginal soil it is the one parameter that genuinely improves over the years.
• Discipline in irrigation. Small, frequent doses. Moisture sensors instead of a hand in the soil. On a marginal block over-irrigation kills faster than drought.
• Minimising machinery passes, particularly on wet soil, with fixed traffic lanes.
• Rootstock. Actinidia genotypes with waterlogging tolerance are being trialled, and differences between rootstocks in their behaviour under excessive moisture do exist [5] [6]. It is a field that is developing, and what is available at the moment of planting is checked then.

8. What the effort really costs

The cost of establishing a new kiwifruit planting is of the order of 60,000 to 70,000 euros per hectare, and about four years are needed to the first commercial crop. On a marginal block, the earthworks, the drainage and the continuous organic improvement are added on top of that.

But that is not the real cost. The real cost is something that does not go into a budget:

That is why the decision about a marginal block is not only agronomic. It is also a question of whether the time, the willingness and the tools exist to monitor it at that intensity.

9. When the answer is no

There are situations in which no amount of effort offsets the risk. They are not many, but they are clear:

• A water table that rises seasonally into the root zone. Saturated soils kill vines at any time of year [1], and the problem is not solved with ridges when the water comes from below.
• Irrigation water outside the limits for chloride or sodium, with no alternative source. It cannot be corrected.
• A block in a frost-prone position, a low point, a closed basin, stagnant cold air in spring.
• Strongly calcareous soil, above 10% calcium carbonate.
• An inadequate or unreliable quantity of water at the peak of summer.

10. Sources

The numbers in the text refer to the list below.

• [1] Beutel, J.A. Kiwifruit. Small Farm Center, University of California, Davis. Source for the limits of pH below 7.3, conductivity 0.75, boron 0.25 ppm, the irrigation water quality limits, the comparison of loam and sandy loam soils, the observation that second-class soils give good and occasionally excellent production with correct management, the white salt deposits on the fruit from overhead irrigation, and the damage caused by wind.
• [2] Xiloyannis, C. and Xiloyannis, E. (2026). Georgia-Ktinotrofia, issue 04/2026. Source for root density, the 2% intercellular space against 7 to 11% in peach and citrus, and the five-hour rule for oxygen depletion in saturated soil. These data are developed in our article on kiwifruit vine decline syndrome.
• [3] Studies on the aetiology of kiwifruit decline: interaction between soil-borne pathogens and waterlogging. Plant and Soil (2020). Source for the higher incidence on silty soils with poor drainage, for the role of machinery compaction, and, critically, for the record of cases on well-drained soils and in plantings on ridges.
• [4] Growth, ion content and photosynthetic performance of salt-stressed kiwifruit plants. Irrigation Science. Source for the salt sensitivity of kiwifruit and for the reduction in photosynthetic rate as leaf chloride increases.
• [5] Potential of Different Actinidia Genotypes as Resistant Rootstocks for Preventing Kiwifruit Vine Decline Syndrome. Horticulturae (2022). Source for the evaluation of genotypes as resistant rootstocks.
• [6] Physiological and image-based phenotyping assessment of waterlogging responses of three kiwifruit rootstocks and grafting combinations. Source for the differences between rootstocks in their behaviour under waterlogging.