WateringTimesWatering plan, $19
Digitalis ferruginea, WUCOLS IV

How often to water rusty foxglove in California

In July on the north-central coast, established rusty foxglove in loam needs a deep watering about every 22 days: about 1.5 gallons each time for a plant 2 feet across, about 0.5 gallons a week. Rusty foxglove is a biennial or short-lived perennial that forms a rosette of dark green, lance-shaped leaves. In summer it sends up spires 3 to 5 feet tall packed with small, bell-shaped, yellow-brown flowers that bees visit. It grows in almost any soil that is neither very wet nor very dry, and all parts are toxic if eaten.

PerennialRated for 3 of 6 zones

How often to water rusty foxglove, month by month

Your city
Plant width
2 ft
Your soil

Type your city above and the days between waterings and the gallons appear here, worked out from your city's climate table. Or read the figures by climate zone further down.

Every month, on your water days. The personal plan prints this for rusty foxglove and the rest of your yard, on the days your water supplier allows.Get the plan for $19

How this is worked out: established roots fill the top 1 foot of soil, and you water again when that soil has dried halfway. Loam soil holds about 1.5 inches of water per foot. Water the whole area the plant covers, and skip a watering after a good soaking rain.

Which soil do you have?

Dig down a few inches, take a handful of moist soil and squeeze it.

  • Sandy: gritty, falls apart when you open your hand, will not form a ball.
  • Loam: forms a soft ball that crumbles when you poke it.
  • Clay: forms a firm, sticky ball and squeezes out into a ribbon between thumb and finger.

Still not sure? Pick loam. Most garden beds sit between sand and clay.

How to measure plant width

A shrub with its width marked from one side to the other and the circle under it shaded blue

Measure across the plant, from the tips of the leaves on one side to the tips on the other.

Water the whole area the plant covers, shown in blue. The gallons here cover that area.

A wider plant means more gallons each watering, not more waterings. While it is young, measure again each spring.

How to tell it needs water

  • Soil dry 2 inches down around the rosette while the spire is growing signals rusty foxglove needs a soak
  • Rosette leaves going limp in the afternoon can indicate thirst
  • Flower spikes fading early and lower blooms dropping can follow a dry spell in bloom
  • A rosette rotting at the center in waterlogged soil points to overwatering

How to water it

  • Water the soil around the rosette, keeping water off the crown
  • Wet the ground 6 to 8 inches deep, then let the top couple of inches dry
  • Plant in humus-rich soil in partial shade, though sun or shade also work
  • Cut the main flower spike after bloom to encourage side spikes
  • Leave a few spikes to ripen if you want self-sown seedlings

Through the seasons

Water a new plant regularly while the rosette grows. It usually flowers in its second summer and is often treated as a biennial. Established plants grow best when the soil avoids both extremes, never soggy and never parched. After bloom, cut the main spike and let side spikes follow. On the north-central coast, WUCOLS rates rusty foxglove low water. The south coast and South Inland carry a moderate water rating. WUCOLS marks it as not suited to the high desert or the low desert, and has not evaluated it for the Central Valley.

In pots

Rusty foxglove can grow in a deep pot, which steadies its tall spires. Use a humus-rich, well-drained mix. Water when the top inch or two feels dry, and let the surplus run out freely. In summer, check every couple of days, and keep the pot in part shade. Empty the saucer. Wear gloves when handling it. In winter, water only when the mix dries. Stake the spire if wind rocks the pot.

1 Your climate zone six WUCOLS zones, each from its own reference city
Not ratedWUCOLS does not rate Rusty Foxglove for the Central Valley zone
A year
no figure
Reference
Sacramento climate table
Counts
Plant need, before sprinkler losses

WUCOLS lists Rusty Foxglove as not evaluated for the Central Valley zone, so no monthly figure is computed here.

Monthly water need by climate zone

Rusty Foxglove: gallons per square foot per month, by WUCOLS climate zone

MonthN. CoastC. ValleyS. CoastS. InlandHi DesertLo Desert
Jan0.15–0.780.78––
Feb0.21–0.810.87––
Mar0.35–1.151.3––
Apr0.47–1.41.61––
May0.58–1.611.95––
Jun0.64–1.742.29––
Jul0.64–1.982.51––
Aug0.6–1.862.33––
Sep0.5–1.491.86––
Oct0.35–1.151.33––
Nov0.19–0.840.9––
Dec0.12–0.650.68––
Year4.8–15.518.41––

How this is worked out: the WUCOLS water rating for each zone times that zone’s climate for the month. A dash means WUCOLS does not rate the plant there. The figures are what the plant uses, before sprinkler losses.

Plants with the same water needs 16

Rated not evaluated in the Central Valley, like rusty foxglove. Plants that drink alike can share one valve and one schedule.

Lilyleaf LadybellsAdenophora liliifolianot rated, Central Valleyno Central Valley ratingArnicaArnica montananot rated, Central Valleyno Central Valley ratingFrilly BergeniaBergenia ciliatanot rated, Central Valleyno Central Valley ratingCabbage on a StickBrighamia insignisnot rated, Central Valleyno Central Valley ratingBasket PlantCallisia fragransnot rated, Central Valleyno Central Valley ratingForest SedgeCarex sylvaticanot rated, Central Valleyno Central Valley ratingUmbrella DracaenaDianella ensifolianot rated, Central Valleyno Central Valley ratingBig-Flowered FoxgloveDigitalis grandifloranot rated, Central Valleyno Central Valley ratingWoolly FoxgloveDigitalis lanatanot rated, Central Valleyno Central Valley ratingSunset FoxgloveDigitalis obscuranot rated, Central Valleyno Central Valley ratingMale FernDryopteris filix-masnot rated, Central Valleyno Central Valley ratingAlpine Sea HollyEryngium alpinumnot rated, Central Valleyno Central Valley ratingPurple SpurgeEuphorbia dulcisnot rated, Central Valleyno Central Valley ratingQueen of the MeadowFilipendula ulmarianot rated, Central Valleyno Central Valley ratingDropwortFilipendula vulgaris (Filipendula hexapetala)not rated, Central Valleyno Central Valley ratingGentianGentiana scabra procumbensnot rated, Central Valleyno Central Valley rating
Minutes for your sprinklers

Turn this into minutes on your water days

Every city page has a calculator that takes rusty foxglove, your sprinkler type and the month, and gives the minutes per water day for that supplier's schedule. Or put it in a zone of the personal watering plan and get all twelve months printed.

Questions people ask

How often should I water rusty foxglove in summer?

In July, established rusty foxglove in loam needs a deep watering about every 7 days on the south coast and about every 6 days in the South Inland zone. Sandy soil holds less water, so waterings come closer together. Clay stretches them. Check the soil before each watering and skip one after a soaking rain.

How much water does rusty foxglove need per day?

In July on the north-central coast, established rusty foxglove needs about 0.1 gallons a day for a plant 2 feet across and about 0.3 gallons a day for a plant 4 feet across. Give it in deep waterings spread days apart rather than a little every day, so the whole root zone gets wet.

Does watering for rusty foxglove change across California?

Yes. WUCOLS rates rusty foxglove separately for each of the six California climate zones: low water in the North-Central Coastal zone, not evaluated in the Central Valley zone, moderate water in the South Coastal zone, moderate water in the South Inland zone, not suited to this region in the High and Intermediate Desert zone, not suited to this region in the Low Desert zone. The monthly table above shows how the same rating translates into different gallon amounts as reference evapotranspiration changes.

Is rusty foxglove poisonous?

Yes, all parts are toxic if eaten and can cause severe discomfort and vomiting. Contact with leaves may also cause an allergic reaction. Wear gloves and keep pets away.

Does rusty foxglove come back every year?

It is a biennial or short-lived perennial. Plants often flower in their second year and then decline. Let some seed fall to keep a planting going.

Is rusty foxglove good for bees?

Yes, its flowers provide nectar and pollen for bees and other pollinators. Bloom comes in summer. Water in the morning so flowers stay dry.

How tall does rusty foxglove get?

Flower spires usually reach 3 to 5 feet. The rosette below stays low. Stake spires in windy spots.

Should I cut off the flower spike?

Cutting the main spike after bloom encourages side spikes. Leave a spike to ripen if you want seedlings. Water lightly after cutting back.

More plant watering guides

ArnicaNeemFrilly BergeniaBismarck PalmCabbage on a StickBasket PlantForest SedgeAmerican Hornbeam

Sources