Watering

Tree Age

The plum’s need for moisture depends directly on its age.

Young saplings (1–2 years after planting) are particularly vulnerable. When dug up from the nursery, they lose up to 75% of the active absorbing part of the root system (Krivko, 2014). Their roots are still weak and shallow. Root recovery and establishment are possible only if the soil moisture in the root zone does not drop below 80–85% of field capacity throughout the first growing season (Krivko, 2014). For young trees, continuous, not episodic, access to water is critical.

Fruiting trees with well‑developed root systems are more tolerant of short‑term drought. However, their water demand during fruit filling and yield formation increases many times over. Producing 1 quintal of high‑quality fruit requires 30–40 tonnes of water over the growing season (Kurennoi et al., 1985). The tree cannot “store” water for later – it must be supplied continuously.

Growth Phases

The plum’s greatest water needs coincide with key phenological stages. These are critical periods when moisture deficit causes the most severe damage to yield.

1. Shoot and leaf growth (spring – early summer). At this time, the tree is actively building vegetative mass. For plums, as for other fruit crops, this is one of the most critical stages (Westwood, 1993; Potapov et al., 2000). Water shortage during this period restricts growth and the formation of the future crop.

2. Flowering and fruit set. Lack of moisture during and immediately after flowering can cause massive flower and fruitlet drop. “June drop” is often triggered precisely by water and nutrient deficits (Krivko, 2014). A generous irrigation 2 weeks after blooming helps reduce losses (Kurennoi et al., 1985).

3. Fruit growth and filling. This is arguably the most important stage. During intensive fruit enlargement, the tree consumes maximum water. Lack of moisture leads to smaller fruit size, poorer taste, and reduced market appeal (Agustí, 2010; Gull et al., 2023). Watering at this time is the key to a quality harvest.

4. Flower bud initiation for next year’s crop. This process occurs in July–August and also requires moisture. If the tree suffers drought stress during this period, it sets fewer flower buds, leading to a poor crop the following year (Kurennoi et al., 1985).

Influence of Climate and Soil

Plums grow successfully in various climatic zones, but the watering approach must account for local conditions.

In arid regions (Mediterranean, steppe zones), irrigation is not an optional extra but the main factor for survival and productivity of the orchard (Westwood, 1993). Without irrigation, stable yields of quality plums are impossible.

In temperate and humid regions, the grower’s task is not so much to “add” water but to compensate for dry spells that occur during critical developmental phases. Excess moisture, especially in cool weather, is as dangerous as drought.

A crucial factor is soil type. Plums prefer well‑drained, moisture‑retentive soils. Sandy soils lose water quickly and thus require more frequent watering. Clay soils hold water better but carry a higher risk of waterlogging and root rot. A deep water table (no closer than 2 m) is essential for normal plum development (Westwood, 1993).

Brief summary of plum water requirements:

Key takeaway: The plum is not a water‑loving crop, but it is extremely sensitive to water deficit at key moments of its development. The grower’s job is not just to water, but to water wisely, based on growth stage, weather, and tree condition. Watering plums is not a routine chore but one of the main tools for crop management. In the next section, we will look at when exactly to water to get the maximum benefit.

Young Trees (up to 3–5 years)

For a young sapling, the main goals are to establish and develop a strong root system. It needs constant but moderate moisture in the root zone (Krivko, 2014; Kurennoi et al., 1985).

• Planting year. Water frequently. In the first month after planting, every 5–7 days, applying 20–30 litres per tree (depending on weather). In hot, dry summers, more frequent watering may be needed. It is critical not to let the soil in the root‑zone dry out. Wetting depth – 30–40 cm.
• Years 2–3. Water less often but more abundantly. 3–5 waterings per season are sufficient, depending on the weather. Key times: in spring, before bud break (if little snow), during active shoot growth (May–June), and in dry autumn (pre‑winter moisture‑charging irrigation). One watering – 40–60 litres per tree.
• Control. The main indicator is soil moisture at a depth of 30–40 cm. If a handful of soil from that depth does not crumble when squeezed and does not stick strongly to the hands – moisture is sufficient. If it crumbles – it is time to water (Potapov et al., 2000; Tarasov, 1981).

Fruiting Trees

In mature plums, there are clearly defined critical periods when watering is mandatory, and periods when it is undesirable or dangerous. Watering at the “wrong” time can provoke diseases, fruit cracking, or delay wood ripening, reducing winter hardiness.

General watering schedule for fruiting plums (mandatory in southern and arid regions, weather‑dependent in temperate zones):

1. Spring watering (before flowering). If winter had little snow and spring is dry, water before bud break. This stimulates shoot growth and flower initiation. Rate – 50–70 litres per tree.

2. Watering after flowering (1–2 weeks later). This is one of the most important irrigations. It helps reduce “June drop” when the tree sheds some fruit due to lack of water and nutrients (Krivko, 2014; Kurennoi et al., 1985). This watering insures the future harvest. Rate – 60–80 litres.

3. Watering during fruit filling (2–3 weeks before ripening). The most critical stage. Fruit size and juiciness depend directly on moisture at this time. Watering is mandatory even in temperate climates if the weather is dry. Rate – 80–100 litres per tree. Important: Do not overdo it! Excess water 1–2 weeks before harvest can cause fruit cracking (Westwood, 1993; Gull et al., 2023). If summer is very rainy, skip this watering.

4. Watering after harvest (August–September). This is when flower buds for the next year are being initiated. If the weather is dry, the tree needs moisture. Watering ensures proper flower bud differentiation and boosts next year’s yield (Kurennoi et al., 1985). Rate – 50–70 litres.

5. Pre‑winter moisture‑charging irrigation (autumn, after leaf fall). Conducted if autumn is dry. It saturates the soil with moisture before winter, increasing root frost resistance and protecting them from desiccation (Krivko, 2014; Westwood, 1993). Rate – up to 100 litres per tree. This watering is especially important in regions with harsh, low‑snow winters.

Critical periods (summary):

How to Tell If the Tree Needs Water?

An experienced gardener never waters “by schedule.” He checks soil moisture.

1. Visual assessment: Leaves lose turgor, become limp, and droop. During prolonged drought, leaves start yellowing and drying from the edges (Westwood, 1993).

2. Soil ball test: Take a handful of soil from 20–30 cm depth (in the root zone). Squeeze. If the ball crumbles – the soil is dry, time to water. If you can roll it into a string without cracking – moisture is adequate. If the ball sticks to your hands and water can be squeezed out – soil is waterlogged, no watering needed (Tarasov, 1981).

3. Using instruments: Simple moisture meters (tensiometers) can accurately determine soil moisture at 30–40 cm depth. This eliminates guesswork.

Climate Adaptation

• For southern arid regions (Mediterranean, steppes): Irrigation is the backbone of cultivation. All five waterings listed above are essential, especially during fruit filling. Here, drip irrigation or regular sprinkling is indispensable (Westwood, 1993; Agustí, 2010).
• For temperate regions (Europe, northern US, Chernozem belt): Watering is only needed during dry spells, but it is critical not to miss the fruit‑filling and bud‑initiation stages. In a rainy summer, the number of waterings can be reduced to 1–2, and pre‑winter irrigation is only done if autumn is dry.
• For humid regions (north‑western Europe, parts of China): The main danger is overwatering. Here, the focus should be on drainage, and waterings are done selectively, only during dry periods of the growing season. Pre‑winter charging is often unnecessary.

Key takeaway: There is no one‑size‑fits‑all schedule for watering plums. The key is to observe the weather, tree condition, and soil moisture. Remember the critical phases: flowering‑fruit set, fruit filling, and bud initiation. These are the moments when the tree most relies on your help. In the next section, we will cover how much water to apply in one go for effective irrigation.

Wetting Depth: The Basis of Calculation

The bulk of active plum roots, like those of other fruit trees, are located down to 60–80 cm, with most fine absorbing roots concentrated in the 20–40 cm layer (Westwood, 1993; Potapov et al., 2000). The goal of watering is to moisten that layer.

• For young trees (first 2–3 years), roots are shallow, so a wetting depth of 30–40 cm is enough.
• For mature fruiting trees, water should penetrate to 50–80 cm. If you only wet the surface, roots will stay shallow, reducing drought resistance.

Watering Rates: Practical Values

The exact volume depends on soil type, tree age, and weather. However, there are average guidelines you can use as a starting point.

For young saplings (1st year):

• First 1–2 months after planting – 20–30 litres per tree every 5–7 days (more often in hot weather).
• Subsequent years until bearing – 40–60 litres per watering.

For fruiting trees (from 5–6 years):

• Spring and post‑bloom waterings – 50–70 litres.
• Watering during fruit filling – 80–100 litres per tree. This is the highest amount because the bulk of the crop is being formed at this time (Kurennoi et al., 1985; Krivko, 2014).
• Pre‑winter moisture‑charging – up to 100 litres.

Important addition: These rates are for one tree in temperate conditions. On sandy soils, water more often but with smaller amounts (to prevent water from draining past the roots). On clay soils, water less often but with larger volumes, as the soil absorbs water more slowly.

How to check if you applied enough? 2–3 hours after watering, dig a small hole 40–50 cm deep at the edge of the root zone. See how deep the soil is wet. If it is dry at that depth – the watering amount was insufficient.

Soil Moisture Monitoring

The best way to avoid errors is to learn how to assess soil moisture using simple, proven methods.

The “soil ball” method (Tarasov, 1981):

Take a handful of soil from 20–30 cm depth (not from the surface!). Squeeze it in your palm.

• If the ball crumbles – soil is dry, need watering.
• If the ball holds together but leaves no wet mark on your hand – moisture is optimal for most growth phases.
• If the ball easily moulds and leaves moisture on your hand – overwatered, no watering needed.
• If water can be squeezed out – soil is waterlogged, dangerous for roots.

Using instruments. For precise control, you can use simple tensiometers (soil moisture meters). They measure moisture at a given depth (usually 30 and 50 cm). This is an invaluable aid, especially in hot weather when visual assessment may be misleading (Westwood, 1993).

Remember soil type. On light sandy loams, water moves deeper faster, so check wetting depth – water may escape beyond the root zone without being retained. On heavy clays, water infiltrates slowly, with a risk of ponding and crust formation – water less often but more generously, and always loosen after absorption.

Calculating Irrigation Rate (for reference)

For those who want a scientific approach, there is a formula for irrigation rate (Krivko, 2014):

N = 100 × H × D × (Wfc – Wact)

where:

• N – irrigation rate, m³/ha.
• H – depth of the wetted layer, m (for plums 0.5–0.8 m).
• D – bulk density of soil, t/m³ (for loams about 1.2–1.4).
• Wfc – soil moisture at field capacity (how much water the soil can hold), %.
• Wact – actual soil moisture before irrigation, %.

For the home gardener, this formula is overkill, but it helps understand why irrigation rates depend on soil – the heavier the soil, the more water needed to wet it to the required depth.

Quick reference for watering rates (per tree):

Key takeaway: The amount of water per irrigation is determined by root‑zone depth and soil type. One deep watering is better than two‑three shallow ones. The main control indicator is moisture at 30–40 cm depth. Use simple field methods (soil ball) to know exactly when and how much to water. In the next section, we will look at watering methods and determine which is best for plums.

Basin (or Bowl) Irrigation

This is the most common and traditional method, ideal for hobby growers with a few trees.

How it’s done. A shallow basin or bowl is formed around the trunk, with a diameter roughly corresponding to the canopy spread (or slightly less). The edges are mounded with soil to a height of 15–20 cm to prevent water from running off. Water is poured directly into this reservoir (Krivko, 2014; Kurennoi et al., 1985).

When and for whom it is suitable.

• For young trees – this is the main method for the first 3–4 years. The root system is still compact, and water is delivered precisely to the root zone.
• For mature trees – effective on small plots and when there is no irrigation system. Suitable for hand watering with a hose or buckets.

Advantages:

• Simplicity. No special equipment required; accessible to everyone.
• Precision. Water goes straight to the root zone, not wasted on inter‑rows.
• Fertiliser integration. Liquid fertilisers (herb infusions, manure slurry, mineral solutions) can be easily applied into the basin (Krivko, 2014).

Disadvantages:

• Labour‑intensive. With many trees, manually watering each basin takes considerable time and effort.
• Limited wetting volume. Only part of the root zone is wetted, which may restrict root development in width (Westwood, 1993). This is especially critical in arid regions where the tree needs to “mine” water from a larger area.
• Crust formation. After watering, the basin surface often seals and forms a crust, requiring loosening to restore air access to roots.

Gardener’s tip: When basin watering, make the basin large – up to 1.5–2 m in diameter for a mature tree – so water reaches the peripheral roots. After water soaks in, mulch the basin or lightly cover with dry soil to prevent cracking and reduce evaporation (see Chapter 5).

Drip Irrigation

This method is considered the most advanced and efficient for irrigating fruit crops, especially in commercial orchards and on sites with limited water resources (Krivko, 2014; Potapov et al., 2000).

How it works. Water is supplied in small amounts (drops) directly to the root zone through a system of tubes and emitters placed near each tree. Water flows continuously or on a programmed schedule, maintaining a constant optimal moisture in a limited soil volume (Westwood, 1993).

When and for whom it is suitable.

• Ideal for arid regions with water scarcity, where every litre counts.
• For slopes and uneven terrain where other methods are ineffective.
• For large orchards and commercial farms (Krivko, 2014). Increasingly used in home gardens thanks to affordable kits.

Advantages:

• Water saving. Compared to furrow irrigation, water consumption is reduced by 1.5–2 times (Krivko, 2014). Water is used with almost no loss.
• Precision. Water is delivered exactly where the roots are. Inter‑rows stay dry, preventing weed growth.
• Automation. The system can be fully automated with a timer set for the whole season.
• Fertigation compatibility. Drip irrigation works perfectly with fertigation – applying fertilisers through the irrigation water, ensuring maximum nutrient efficiency (Krivko, 2014).
• No soil compaction. Surface is not washed away; soil structure is preserved (Krivko, 2014).

Disadvantages:

• High initial equipment cost. Especially if using quality emitters and filters.
• Water quality dependence. Water must be well‑filtered, otherwise emitters clog quickly (Krivko, 2014; Westwood, 1993).
• Limited root system volume. With constant drip irrigation, roots develop mainly in the wet zone, which may reduce drought tolerance if the system is turned off (Westwood, 1993).
• Need for winter dismantling in cold regions to prevent freeze damage to tubes.

Gardener’s tip: For a garden plot with a few trees, you can buy an inexpensive drip kit with a timer. This saves you from daily manual watering. Use pressure‑compensating emitters to ensure even distribution even on uneven ground.

Sprinkler Irrigation

This method mimics natural rain: water is sprayed through special nozzles above or under the tree canopy (Krivko, 2014; Westwood, 1993).

Types of sprinkling:

• Over‑canopy – sprinklers are placed above the canopy and water the entire orchard area. Often used in commercial orchards with sprinkler machines (e.g., DDN‑70, DDN‑100) (Krivko, 2014).
• Under‑canopy – sprinklers are placed under the canopy, directing water into the root zone. This is more economical.
• Fine‑mist – creates a “water fog” and is used in hot weather to cool and increase humidity, helping to prevent leaf stress (Krivko, 2014).

When and for whom it is suitable.

• For large orchards with a water source with sufficient pressure.
• For frost protection – sprinkling during blooming can raise air temperature by 1–2 °C and save flowers from damage (Krivko, 2014; Kurennoi et al., 1985).
• For sandy soils where uniform wetting is difficult by other methods.

Advantages:

• Uniform wetting of a large area.
• Improved microclimate – increased humidity and lowered temperature on hot days, benefiting photosynthesis and reducing water loss (Krivko, 2014).
• Possible use for frost control and for fertigation (Westwood, 1993).
• Less manual labour, especially with a permanent system.

Disadvantages:

• High water and energy consumption (requires pressure 2–4 atm).
• Risk of fungal diseases with over‑canopy sprinkling, especially in wet weather, as leaves are wetted (Westwood, 1993; Gull et al., 2023). For plums, which are susceptible to moniliosis, this is a significant drawback.
• Soil compaction and erosion with strong jets (Krivko, 2014).
• Wind dependence – some water may be blown away and miss its target.

Gardener’s tip: For home orchards, it is better to use under‑canopy sprinklers that direct water under the canopy without wetting leaves. Or apply sprinkling only during the most critical periods (before and after flowering) and rely on drip or basin irrigation at other times. During fruit filling, avoid sprinkling to prevent cracking and disease.

Subsurface Irrigation

This method delivers water directly to the roots through a system of pipes buried in the soil at 40–60 cm depth (Krivko, 2014; Westwood, 1993).

How it works. Perforated pipes (ceramic or plastic) are laid in the inter‑rows or along tree rows. Water flows through them under low pressure and seeps into the soil through holes, wetting the root zone from within (Westwood, 1993).

When and for whom it is suitable.

• For professional orchards where automation and water saving are essential.
• In arid regions with water scarcity.
• On soils with a high water table (with proper design) to avoid waterlogging from surface irrigation.

Advantages:

• Maximum water use efficiency – nearly 100% reaches the root zone, with no losses to evaporation or runoff (Krivko, 2014).
• No surface crust or compaction.
• Preservation of soil structure and aeration – the surface remains dry and loose.
• Compatibility with fertigation – fertilisers are delivered straight to the roots.
• Complete independence from wind and topography.

Disadvantages:

• Complex and costly installation – laying the system requires specialised work.
• Risk of clogging and system failure.
• Difficult repair and maintenance (Westwood, 1993).
• Need for regular flushing to prevent siltation of holes.
• Risk of soil salinisation when using hard water, as salts may accumulate in the wet zone (Krivko, 2014).

Gardener’s tip: For a hobby orchard, subsurface irrigation is usually not worth the cost and complexity. It is mainly used by professionals on large areas. If you do decide to install it, be sure to include water filters and a pipe flushing system.

Comparison of Watering Methods: How to Choose?

Practical advice for the home gardener:

1. If you have 1–3 trees, the best choice is basin irrigation followed by mulching. It is cheap, reliable, and environmentally friendly.

2. If you want to automate and have a budget, drip irrigation is the ideal solution. It saves water, time, and allows precise fertiliser dosing.

3. Sprinkling in a home garden for plums is only justified in two cases: for frost protection and for refreshing irrigation in extreme heat (fine‑mist sprinkling). At other times, it increases the risk of fungal diseases.

4. Subsurface irrigation is a professional choice. For a standard orchard it is overly complex and expensive.

Key takeaway: There is no universal “best” watering method. The choice depends on your resources, climate, and orchard size. The essential thing is that water is delivered timely and in the right amount directly to the root zone. Combining methods (e.g., drip irrigation with occasional sprinkling to wash leaves) can be the most effective solution. In the next section, we will discuss how to retain moisture in the soil after watering and reduce irrigation frequency.

Mulching

Mulch is a layer of organic or inorganic material spread over the soil surface in the root zone. This is arguably the most effective and accessible way to conserve moisture (Agustí, 2010; Martin, 2019).

How it works:

• Reduces evaporation. Mulch acts as a barrier between moist soil and dry air, sharply reducing water loss (Martin, 2019; Gull et al., 2023).
• Suppresses weeds. Weeds are fierce competitors for water. Mulch blocks light, preventing their germination (Westwood, 1993).
• Regulates soil temperature. In summer, mulch protects roots from overheating; in winter, from freezing. This is especially important for the shallow root system of plums (Martin, 2019).
• Improves soil structure (organic mulch). As organic mulch decomposes, it enriches the soil with humus, improving permeability and water‑holding capacity (Agustí, 2010; Martin, 2019).
• Prevents surface crusting. Crust hinders aeration and makes it harder for water to penetrate during subsequent irrigations.

Types of mulch:

1. Organic mulch:

• Materials: well‑rotted manure, compost, peat, straw, hay, mown grass, wood bark, sawdust, leaf litter (Agustí, 2010; Martin, 2019).
• Advantages: improves soil fertility, attracts earthworms, gradually decomposes and feeds the tree.
• Disadvantages: needs regular replenishment (1–2 times per season); fresh organic matter (straw, sawdust) may cause nitrogen tie‑up by microbes, so better apply with nitrogen fertiliser.

2. Inorganic mulch:

• Materials: black polyethylene film, landscape fabric, spunbond, roofing felt, pebbles, gravel.
• Advantages: durable, highly effective weed suppression, better spring soil warming to accelerate growth.
• Disadvantages: does not improve soil structure; black film can overheat roots in hot climates; requires careful installation and removal; reduces oxygen supply to soil (Agustí, 2010).

Recommendations for mulching plums (Martin, 2019; Kurennoi et al., 1985):

• Layer thickness: optimal organic mulch thickness is 8–12 cm. Thinner is less effective against evaporation and weeds; thicker may impede aeration and cause bark rotting (especially in young trees).
• Mulching radius: mulch the entire root‑zone area, leaving 8–10 cm free around the trunk to avoid bark rot.
• Timing: best applied after the first spring watering and soil loosening, when the ground is warm and moist.
• Replenishment: as organic mulch decomposes, top it up to maintain the original thickness.

Soil Management: An Alternative to Deep Digging

How you manage soil in the orchard directly affects its moisture and structure. There are two main approaches, which can be used separately or in combination (Agustí, 2010; Westwood, 1993; Krivko, 2014).

1. Bare fallow (soil kept under cultivation).

This method is practiced in regions with insufficient rainfall (Agustí, 2010; Kurennoi et al., 1985). Soil in inter‑rows and root zones is regularly tilled to prevent weeds. It remains clean and loose.

Tip: In arid areas (southern Russia, Mediterranean), bare fallow is the main way to accumulate and conserve moisture. In temperate climates, it is often combined with mulching.

2. Sodding (grass cover).

Perennial grasses (cereal or legume‑cereal mixtures) are sown in inter‑rows and regularly mown, leaving clippings as mulch (Agustí, 2010; Westwood, 1993; Potapov et al., 2000).

Recommendation: For a home orchard in a temperate climate, a combination is optimal: root zone kept under mulch (or bare fallow), and inter‑rows under sod (Agustí, 2010). In arid regions, bare fallow with mulching is preferable.

Weed Control

Weeds are the main “water consumers” in the orchard. They not only intercept moisture but also absorb nitrogen and other nutrients (Westwood, 1993; Gull et al., 2023).

Control principles:

• Eliminate in the critical period. Weed control is most important in the first half of summer, when the tree is actively growing and setting fruit.
• In the root zone – complete suppression. Within a radius of 1–1.5 m from the trunk, weeds should be absent throughout the growing season.
• Methods:
• Hand weeding – effective but labour‑intensive.
• Tillage (cultivation) – kills weeds and breaks capillaries through which water rises to the surface (Westwood, 1993).
• Mulching – the simplest and most reliable for root zones.
• Herbicides – used in commercial orchards (glyphosate, simazine, atrazine) strictly in the trunk strips, following instructions, avoiding contact with leaves and bark (Westwood, 1993; Krivko, 2014; Kurennoi et al., 1985). In home gardens, it is better to avoid herbicides due to phytotoxicity risks.

Practical Tips for Moisture Conservation

1. Always mulch. This is the most effective and eco‑friendly method. Use mown grass, straw, compost. Layer – 8–10 cm. Refresh in spring after the first watering.

2. Loosen properly. Loosen the soil in the root zone after each watering or heavy rain, once it has dried slightly. This destroys weeds and breaks the surface crust. Loosening depth – 5–8 cm to avoid damaging shallow roots.

3. Choose soil management according to climate. In arid zones – bare fallow with mulch. In regions with adequate moisture – sod inter‑rows and mulch in the root zone.

4. Protect the roots. Avoid deep digging of root zones (deeper than 10–15 cm). Most absorbing roots of plum are shallow. Use light cultivation or a hoe.

Key takeaway: Moisture conservation starts with simple but regular actions. Mulching reduces evaporation by 30–40% and significantly cuts the need for watering. Keeping the root zone clean of weeds and loose ensures that every litre of water is used by the tree to maximum benefit. In the next, final section, we will look at typical watering mistakes and how to avoid them.

Mistake 1. Shallow Watering – “Tick‑box Watering”

This is the most common and insidious mistake. The gardener pours 10–20 litres under the tree, thinking the job is done. In reality, the water only wets the top 10–15 cm of soil, never reaching the main root mass.

Why it is bad:

• Roots deprived of moisture at depth do not grow downward, staying shallow. This reduces drought tolerance (Westwood, 1993).
• The surface layer dries out quickly, and the tree is stressed again.
• Water and time are wasted.

How to avoid:

• Water infrequently but deeply. For a mature tree – at least 50–80 litres per application (see Chapter 3).
• Check wetting depth. 2–3 hours after watering, dig a hole 40–50 cm deep at the edge of the root zone. If it is dry at that depth – the watering amount was insufficient.
• Use drip irrigation or basin watering so water goes downward, not spreading over the surface.

Mistake 2. Overwatering and Waterlogging

“More water is better” – a dangerous misconception. Excess moisture is as harmful as deficiency. Plums do not like “wet feet.”

Why it is bad:

• Waterlogging displaces oxygen from the soil, which roots need for respiration (Westwood, 1993). Root rot begins.
• In waterlogged soil, fungal pathogens that cause root rots, chlorosis, and other diseases thrive (Agustí, 2010; Kurennoi et al., 1985).
• Excess moisture during fruit filling causes cracking, loss of market quality, and rot (Westwood, 1993; Gull et al., 2023).
• The tree “luxuriates” – produces excessive vegetative growth at the expense of fruiting and prepares poorly for winter (Krivko, 2014).

How to avoid:

• Always check soil moisture before watering (soil ball method, see Chapter 3).
• Do not water if the soil is still wet after rain.
• Ensure good drainage on the site. On heavy clay soils, water less often and with smaller amounts; in rainy weather, skip watering.
• If the tree grows in a low spot where water accumulates, create drainage ditches or plant on small mounds (Westwood, 1993).

Mistake 3. Watering at the Wrong Time of Day

Watering in the middle of a sunny day is a common mistake, especially in hot climates.

Why it is bad:

• Much of the water evaporates before it can soak in (especially with sprinkling).
• Water droplets on leaves act as lenses, potentially causing sunburn (Gull et al., 2023).
• Humidity and heat create a favourable environment for fungal diseases.

How to avoid:

• Water early morning (before 8–9 a.m.) or evening (after 6–7 p.m.) when evaporation is minimal.
• In cool weather, watering at any time is acceptable, but morning is better so excess moisture dries by night.
• With drip irrigation, time of day is less critical because water goes directly to roots, but evening watering is still preferable (less evaporation loss).

Mistake 4. Watering During Flowering

Sometimes gardeners water plums during blooming, fearing drought. In most cases, this is unnecessary.

Why it is bad:

• Heavy watering with cold water during flowering can cause flower drop and reduce fruit set (Agustí, 2010).
• Wet weather during flowering hinders bee and pollinator activity, also reducing yield (Kurennoi et al., 1985).
• If flowering coincides with frosts, sprinkling can help, but that is a special technique, not routine watering (Westwood, 1993).

How to avoid:

• The best time for the first spring watering is before bud break or immediately after flowering (1–2 weeks later), when fruit set has begun (Kurennoi et al., 1985; Krivko, 2014).
• If spring is very dry and flowering is heavy, a light watering with warm water in the morning, avoiding wetting flowers, may be acceptable. But it is better to wait until after blooming.

Mistake 5. Watering with Cold Water

Watering trees with water from a borehole or well that is much colder than the soil temperature causes stress.

Why it is bad:

• Cold water reduces root activity, slows nutrient uptake, and may promote fungal diseases (Westwood, 1993).
• Sudden temperature shock damages absorbing rootlets.

How to avoid:

• Fill containers (barrels, tanks) in advance so water warms to ambient temperature (20–25 °C) in the sun.
• If you use a drip system, water in the pipes warms naturally, so the problem is less acute.

Mistake 6. Watering During Rain

This seems obvious, but some gardeners water on schedule regardless of rainfall.

Why it is bad:

• Overwatering (see Mistake 2).
• Waste of water and time.

How to avoid:

• Rely on soil moisture, not a schedule.
• If a good rain has fallen, delay watering for 3–5 days (depending on temperature and soil type).
• In a rainy summer, reduce waterings to a minimum, limiting to critical periods (fruit filling, if rain is scarce).

Mistake 7. Stopping Watering After Harvest

Many gardeners assume the tree no longer needs water after fruit picking. This is a serious error.

Why it is bad:

• July–August is the time of flower bud initiation for the next year. Lack of moisture in this period leads to poor blooming the following year (Kurennoi et al., 1985).
• A tree weakened by summer drought winters poorly.

How to avoid:

• Water the plum after harvest if the weather is dry (rate – 50–70 litres per tree).
• Carry out autumn moisture‑charging watering in dry autumn – this ensures good overwintering (Westwood, 1993; Krivko, 2014).

Quick Error Checklist

Key takeaway: Watering plums is a manageable process. Avoid extremes: shallow watering and overwatering. Watch weather and tree condition, not the calendar. Remember that the most reliable assistant is a simple soil moisture test. Careful attention to water pays off in tree health and excellent harvests.