Prolonged drought is becoming increasingly common, placing greater demands on how we maintain our plantings. Proper watering is essential – but how much, how often, and exactly how depends on the type of planting, location, soil type, and whether the plants are newly planted or established.

In this blog, we provide practical watering guidelines per planting concept during drought conditions. We also discuss influencing factors such as sun, wind, and soil, and offer tips for efficient and sustainable watering practices.

Woody plants vs. herbaceous planting concepts

Watering woody plants such as trees and shrubs differs significantly from herbaceous planting concepts. Woody plants typically have deeper root systems and can access moisture from greater depths. Therefore, they need watering less frequently but in larger volumes — think 30 to 50 liters per tree or shrub, depending on size.

Herbaceous plants generally have shallower roots, making them more sensitive to drought. They require more frequent watering, but in smaller amounts per square meter.

Key Differences:

• Woody plants: water deeply, less often, large volumes (target root zone or tree base).
• Herbaceous plants: water more regularly*, shallowly across the surface.

*) More often than trees, but certainly not too often! Short drought intervals stimulate the plant’s root system.

Note: Newly planted trees and shrubs are temporarily vulnerable. During their first growing season, they need regular watering (sometimes 2–3x/week) until they are established.

TIP: FYP soil sensors can measure soil moisture up to 150 cm deep using the optional antenna cable, making them suitable for both herbaceous concepts and deep-rooted trees/shrubs.

Watering for newly planted concepts (First Year)

Young plantings lack deep root systems. During the first weeks/months, they need more frequent and higher water input.

Recently planted summer-flowering bulbs

• Frequency: In extended dry periods during spring/summer (>14 days without rain), once every two weeks
• Amount: ± 20 liters per m²
• Extra Tip: Water immediately after planting to ensure contact between bulb and soil and for immediate activation.

New perennial plantings (from potted plants)

• Frequency: 2x per week for up to 6 weeks after planting, then reduce
• Amount: ± 20 liters per m²
• Note: Check daily during hot and windy weather!

New perennial or wildflower mats

• Frequency: 3x per week for the first 3 weeks, then reduce to 2x/week in drought
• Amount: ± 15–20 liters per m²
• Note: Press mats firmly into soil to ensure root contact.

Freshly sown wildflower mixes

• Frequency: Light watering daily (!) until germination (±10 days), then 2–3x/week
• Amount: ± 5–10 liters per m² per session
• Note: Use a fine spray to prevent seed displacement. Exotic, annual mixes are shallower-rooted and less resilient, requiring more frequent watering than natural or native (perennial) mixes.

Watering in drought by planting concept (established plantings)

Older plantings have more established roots and can largely survive independently. Only during prolonged drought is additional watering needed.

Flower bulbs (planted in previous years)

• Frequency: In prolonged drought (>14 days without rain), once every two weeks
• Amount: ± 20 liters per m²
• Note: Only water during the foliage stage after blooming (not during dormancy), or before blooming if soil is very dry.

Perennial plantings (at least 1 full growing season, from potted plants)

• Frequency: During drought, once every 7–10 days
• Amount: ± 20 liters per m²
• Note: Older plants are more robust due to deeper roots, but still benefit from support during sustained sun + wind.

Perennial/Wildflower mats (1 year or older)

• Frequency: During drought, once every 5–7 days
• Amount: ± 15 liters per m²
• Note: Diverse mats are resilient, but flowering will decline without water and biodiversity may suffer long-term.

Sown wildflowers (native perennial mixes)

• Frequency: During prolonged drought, once a week
• Amount: ± 10–15 liters per m²
• Note: Native wildflowers are often deeper-rooted and more resilient, requiring less frequent watering

Factors influencing water requirements

The above quantities and frequencies are guidelines (!) — practical situations vary based on:

• Sun: Full sun increases evaporation by up to 50% compared to partial shade.
• Wind: Wind accelerates moisture loss from both plants and soil. Windy areas/seasons require up to one extra watering per week.
• Soil Type: Organic matter content largely determines water retention:
  • Sand: Dries quickly, needs frequent (but light) watering.
  • Clay: Retains water better, but harder to re-wet once dry.
  • Loess/loam: Ideal balance, needs less frequent watering.

Unsure? Contact Flower Your Place — we’re happy to share our expertise.

How do you know it’s time to water?

• Keep an eye on the weather forecast.
• Watch for visual cues:
  • Wilting, dull-colored leaves (e.g., Rudbeckia, Salvia).
  • Early flower closure can indicate stress.
  • Discolored edges or curling leaves in perennials.
• Do the spade test: Dig ± 30 cm deep and feel the soil. If it’s dry at the bottom — it’s time to water, even older plantings.
• Specifically for bulbs:
  • Let foliage die back naturally. If it turns yellow and limp prematurely, check for root dryness.
  • Do not water dormant bulbs (July–September) unless there’s green foliage that is limp.
• Compare locations: Some areas dry out faster than others. Monitor vulnerable spots and compare them to more resilient ones.

Optimize with sensors

Modern tools like FYP Soil Sensors provide real-time soil moisture monitoring. The management platform offers insights and proactive alerts for over- or under-watering, reducing:

• Stress for plants (and staff)
• Plant loss
• Wasteful watering

Given their modest monthly cost, the savings they enable make these sensors a no-brainer.

How to water the right way

• Use a soft spray nozzle: prevents seed/soil displacement and improves absorption.
• Preferably water early in the morning – less evaporation, and plants can dry during the day.
• Deep, infrequent watering is better than shallow, daily watering — promotes resilience and reduces costs.
• Use rainwater, surface water, or collected greywater whenever possible.

Healthy soil needs less watering

Prevention is better than cure. A healthy soil helps reduce watering needs.

• Ensure dense (under)planting
• Mulch with clippings from perennials or wildflowers to reduce evaporation
• Improve soil structure with compost or other organic matter: a sponge holds more water than dust.