Flower beds and seasonal colour: close drip rows, short and often.
Bedding flowers such as impatiens, coleus and scarlet sage are among the thirstiest plants in a garden, with shallow roots in soil that dries fast. This guide helps you decide which zone they go on, how to lay the dripline, and how long and how often to run it. Succulents sit at the other end of the water scale: the two never share a valve.
Written for homeowners and estate and facility managers. Updated .
Key points
- Put flower beds on a valve of their own, never shared with the lawn, shrubs, trees or a bed of succulents.
- Lay dripline in close, even rows under mulch, so every shallow root gets water while leaves and flowers stay dry.
- Water early in the morning, short and often, and split a long run into two shorter ones.
- Pin the lines on the surface so they lift aside when you replant, and flush them before you reconnect.
- Check the soil and the plants every week, and change the run time when they wilt, yellow or rot.
On this page
Why flower beds get a zone of their own
A zone is the area one valve waters, all for the same time. California's landscape rules define a hydrozone as part of a landscape with plants of similar water needs and similar rooting depth: in practice, plants in similar sun and soil, on one valve, with one run time.
Bedding flowers sit at the thirsty end. University of California advice groups flower beds with lawns: shallow roots that need frequent, shallow watering. University of Florida advice says annuals need relatively high amounts of water.
Even so, a flower bed never shares a valve with a lawn: sprays would wet the flowers, and drip needs its own filter and pressure regulator. Shrubs and trees root deeper and want longer, less frequent watering. California does not allow high and low water needs, such as flowers and succulents, in one hydrozone, and Hunter's drip guide gives each hydrozone its own valve.
Sun and shade split beds too: California asks for similar sun on each valve, so a shady bed of impatiens and a sunny bed of marigolds are two zones.
Succulents and drought-tolerant bedsZoning a whole home gardenShrub beds on drip
Sources: California Code of Regulations, Title 23, section 490.2 (2025), Model Water Efficient Landscape Ordinance: definitions of hydrozone and plant factor; California Code of Regulations, Title 23, section 493.2.2 (2025), Model Water Efficient Landscape Ordinance: irrigation design plan, subsections (c)(7)(A) and (d)(8); UC Master Gardeners of Napa County (2021), Wise watering of landscapes, by Dean Donaldson: group 1, turfgrass and flower beds; UF/IFAS Gardening Solutions, Bedding plants: annuals, perennials and bulbs; Hunter Industries (2015), Drip Irrigation Design and Installation Guide (LIT-496), page 10.
Plants for sunny and shady beds
All five plants below appear in a survey of 25 gardens around Jos, in the Nigerian Journal of Botany. The notes on sun, height and water come from NC State University's plant database; watch how your own mix behaves and adjust.
Their roots stay shallow. Arizona's extension service puts the roots of mature lawn and garden plants in the top 15 to 30 cm, against 30 to 60 cm for shrubs and 45 to 90 cm for trees, and says deeper roots need watering less often.
| Plant | Sun or shade | Height | Water notes |
|---|---|---|---|
| Impatiens, or busy Lizzie (Impatiens walleriana) | Part to full shade | 15 to 60 cm | Wilts in hot, dry spells; rots if overwatered |
| Coleus (Coleus scutellarioides, once Coleus blumei) | Part shade | 15 to 90 cm | Moist, loose soil; may wilt in full sun |
| Scarlet sage (Salvia splendens) | Sun to part shade | 30 to 90 cm | Not drought tolerant |
| French marigold (Tagetes patula) | Sun to part shade | 15 to 30 cm | Drought tolerant once established; prone to mildew and rots |
| Cockscomb (Celosia argentea, once Celosia cristata) | Full sun | 23 to 46 cm | Copes with dry soil; crowding and humidity rot the flowers |
Sources: Namo, Igoh and Agyeno (2021), Floriculture and national economy: a case study of the Jos Plateau, north-central Nigeria, Nigerian Journal of Botany 34(2): Table 9; NC State Extension, Gardener Plant Toolbox: Impatiens walleriana; NC State Extension, Gardener Plant Toolbox: Coleus scutellarioides; NC State Extension, Gardener Plant Toolbox: Salvia splendens; NC State Extension, Gardener Plant Toolbox: Tagetes patula; NC State Extension, Gardener Plant Toolbox: Celosia argentea; University of Arizona Cooperative Extension (2017), Watering Trees and Shrubs (AZ1298): root zone depth, and signs of under- and over-watering.
How much water a flower bed needs
Water need in a day, in millimetres, is ETo times the plant factor. ETo is the weather's drying power: the water a well-watered field of grass would lose in your weather, in mm a day. A dry-season month in the north and centre runs at about 6 mm a day: a field study at Afaka, Kaduna State, found monthly averages of about 5.5 to 6.6 mm a day from December to March, and FAO gives 6 to 7 mm a day for a semi-arid area at 15 to 25°C. The south, and the rains, run lower.
The plant factor is the share of ETo a planting needs. California's landscape rules sort plants into four classes, below. They come from California and are a guide only: watch your plants and adjust.
WUCOLS, the University of California list behind the classes, does not rate the five plants above, and rates other bedding flowers, such as periwinkle and wax begonia, moderate. Shallow roots and a relatively high water need put a bed of the flowers above, in this guide's judgement, in the high class.
| Class | Plant factor | In this series |
|---|---|---|
| High | 0.7 to 1.0 | Flower beds: this guide |
| Moderate | 0.4 to 0.6 | For example periwinkle and canna, rated moderate in WUCOLS |
| Low | 0.1 to 0.3 | Aloe and crown of thorns: the drought-tolerant beds guide |
| Very low | Less than 0.1 | Century plant and prickly pear: the same guide |
How ETo is worked out, in the crop guideThe low end: drought-tolerant beds
Sources: Onwuegbunam and others (2025), Actual crop coefficients and yield response factors of irrigated tomato in Afaka, Northwest Nigeria, Journal of Applied Life Sciences and Environment 58(1): study location and Tables 1a and 1b; FAO (1986), Irrigation Water Management Training Manual No. 3: Irrigation Water Needs, chapter 3, Tables 5, 6 and 14; California Code of Regulations, Title 23, section 490.2 (2025), Model Water Efficient Landscape Ordinance: definitions of hydrozone and plant factor; UC Davis (2025), WUCOLS V: Water Use Classification of Landscape Species, plant search; UF/IFAS Gardening Solutions, Bedding plants: annuals, perennials and bulbs.
Dripline in close rows
Hunter's catalogue matches the emitter to the planting: dense planting suits dripline, sparse planting single emitters. A flower bed is dense, so lay a grid of dripline, pipe with drippers built in, in parallel rows.
Hunter's HDL-PC dripline is 16 mm pipe with drippers every 30 or 45 cm, each giving 2.4 or 3.8 litres an hour. Flow is how much water passes in a set time, in litres per hour (L/h) for a dripper; pressure is how hard the water pushes inside the pipe, in bar. HDL-PC is pressure-compensating: each dripper gives the same flow anywhere from 1 to 4.2 bar.
Space the rows for your soil: the shrub-bed guide's table gives Hunter's spacing for sand, loam and clay, and the nearest HDL-PC line. When unsure of the soil, use the tighter spacing. In a flower bed, drippers every 30 cm keep one near each small plant. Run the rows along the longest side, and keep the outer rows within about 10 cm of the edges, which dry fastest beside paths and walls.
Ahead of the zone go its valve, a filter and a pressure regulator. Hunter's filter regulator does both jobs in one fitting, filtering to 100 microns (150 mesh) and lowering the pressure to 1.7 or 2.8 bar. Fit a flush valve at the far end and an air relief valve at the highest point.
- Bedding flowers planted close together, their leaves and flowers kept dry
- Mulch over the soil and the lines
- Rows of dripline, seen end-on, lying on the soil close together
- The damp patches under the drippers join into one moist band where the shallow roots are
- A wire pin holds each row down, so it can be lifted aside when you replant
- The outer row runs close to the path, where the soil dries fastest
Spacing by soil, in the shrub-bed guideHunter HDL-PC driplineHunter PLD dripline fittingsHunter filter regulatorHunter PGV zone valve
Sources: Hunter Industries (2026), Product Catalogue Vol. 41, EMEA metric edition, pages 166, 169, 171 and 172; Hunter Industries (2015), Drip Irrigation Design and Installation Guide (LIT-496), pages 8, 10, 11 and 12.
Keep the leaves and flowers dry
Sprays wet flowers and leaves. University of California pest advice says grey mould can strike wherever plants are often wetted by overhead watering, above all where they are crowded and shaded, as in a full flower bed, and advises drip to keep leaves dry.
Drip also gets more of the water to the roots: FAO gives it about 90 percent, against 60 to 75 percent for fixed sprinklers from USDA.
Water early in the morning: Hunter gives it as the least windy time, with the most pressure and the least evaporation, and warns that early evening watering leaves a lawn wet overnight and more likely to get diseases.
Sources: UC Statewide IPM Program, Home and landscape: Botrytis blight, or gray mold; FAO (1989), Irrigation Water Management Training Manual No. 4: Irrigation Scheduling, Annex I, Table 8; USDA-NRCS (1997), National Engineering Handbook Part 652: Irrigation Guide, chapter 6, Table 6-4; Hunter Industries (2019), Residential Sprinkler System Design and Installation Guide (LIT-226), page 26.
Worked example: a sunny bed in the dry season
The same sum for a succulent bed
Sources: Onwuegbunam and others (2025), Actual crop coefficients and yield response factors of irrigated tomato in Afaka, Northwest Nigeria, Journal of Applied Life Sciences and Environment 58(1): study location and Tables 1a and 1b; FAO (1986), Irrigation Water Management Training Manual No. 3: Irrigation Water Needs, chapter 3, Tables 5, 6 and 14; California Code of Regulations, Title 23, section 490.2 (2025), Model Water Efficient Landscape Ordinance: definitions of hydrozone and plant factor; FAO (1989), Irrigation Water Management Training Manual No. 4: Irrigation Scheduling, Annex I, Table 8; Hunter Industries (2026), Product Catalogue Vol. 41, EMEA metric edition, pages 105 and 172; Hunter Industries (2015), Drip Irrigation Design and Installation Guide (LIT-496), pages 8 and 25; Hunter Industries, X-Core controller: features; UC Master Gardeners of Napa County (2021), Wise watering of landscapes, by Dean Donaldson: group 1, turfgrass and flower beds.
What changes the run time
- Soil. Hunter spaces drippers closer on sand, which drains fast; its residential guide advises shorter, repeated runs on clay and more watering days on sand.
- New plants. While a bed roots in, Hunter's drip guide says keep the soil near as wet as it can hold, to draw roots to the wetted area. Its rough guide for turf and high-water-use plants on dripline, in a semi-arid climate, gives 27 to 45 minutes a day while plants establish, against 18 to 30 once established, five days a week. Each replanting starts this again.
- Season. At Afaka, ETo rose from about 5.5 mm a day in December to about 6.6 in March, so lengthen the runs as the hot months come on. In the rains, count the rain instead of watering by the calendar, and let a rain sensor halt the scheduled watering once a set amount of rain has fallen; it lets the controller water again as the sensor dries.
Watering sandy, loamy and clay soilsPlanning for the dry season and the harmattanTopping up rain in the rainy seasonHunter Mini-Clik rain sensor
Sources: Hunter Industries (2015), Drip Irrigation Design and Installation Guide (LIT-496), pages 8, 24 and 25; Hunter Industries (2019), Residential Sprinkler System Design and Installation Guide (LIT-226), pages 19 and 26; Onwuegbunam and others (2025), Actual crop coefficients and yield response factors of irrigated tomato in Afaka, Northwest Nigeria, Journal of Applied Life Sciences and Environment 58(1): study location and Tables 1a and 1b; Hunter Industries, Mini-Clik rain sensor: product page.
Signs and checks
- Feel the soil at root depth the day after watering: it should be moist, neither soggy nor dust-dry.
- Too little water: dry soil, wilted or curled leaves, older leaves yellowing or browning and dropping. Impatiens wilt fast in hot, dry spells.
- Too much water: soil that never dries, pale or yellow young leaves, wilting young shoots, algae or mushrooms, plants starting to rot.
- Grey, fuzzy mould on the flowers: the bed is too wet or too crowded, or water is reaching the leaves.
- After a run, every plant should have a damp patch beside it; move or add a row to fill dry gaps.
- When the zone is new, note the pressure at the valve and at the flush end, and compare it at later checks.
- Clean the filter and flush the rows as the maintenance guide sets out, and mend trowel cuts at once.
Irrigation maintenance through the seasonSeven causes of drip irrigation failure
Sources: University of Arizona Cooperative Extension (2017), Watering Trees and Shrubs (AZ1298): root zone depth, and signs of under- and over-watering; NC State Extension, Gardener Plant Toolbox: Impatiens walleriana; UC Statewide IPM Program, Home and landscape: Botrytis blight, or gray mold; Hunter Industries (2015), Drip Irrigation Design and Installation Guide (LIT-496), pages 24 and 26.
Replanting without losing the lines
Dripline laid on the soil under the mulch, held down with wire pins, lifts aside when you replant:
- Switch the zone off, rake back the mulch, pull the pins and lift the rows aside.
- Dig and replant, keeping forks and trowels clear of the lines.
- Lay the rows back at the same spacing, with a dripper near each new plant.
- Pin each row about every 1.5 m, and within 30 cm of every fitting.
- Flush each row before you reconnect it, and open up only as much as you can reconnect and flush in one go.
- Run the zone, check that every plant has a damp patch, and mulch over the lines again.
Sources: Hunter Industries (2015), Drip Irrigation Design and Installation Guide (LIT-496), pages 2, 21, 22 and 27; Hunter Industries (2026), Product Catalogue Vol. 41, EMEA metric edition, page 171.
When to ask for a site-specific design
What depends on your site: the water source and how much it gives, the pressure where the system connects, the size and shape of each bed, slopes, sun and shade, and how many zones the supply can run. To start a design, send us:
- State and town or local government area
- Crop, or the type of site
- Area, in hectares, acres or square metres
- Where the water comes from, and how much you think you have
- How you pump today, and what powers the pump
- When you want the system working
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