Repotting guide

When & how to repot Penstemon heterophyllus 'Electric Blue' (Penstemon heterophyllus 'Electric Blue')

Also called Electric Blue penstemon, Foothill penstemon.

More about penstemon heterophyllus 'electric blue'

About Penstemon heterophyllus 'Electric Blue'

Penstemon heterophyllus 'Electric Blue' · also called Electric Blue penstemon, Foothill penstemon · flowering

'Electric Blue' is a Californian foothill penstemon famed for vivid gentian-blue, tubular flowers with violet tints over narrow blue-green foliage in early summer. A low, semi-evergreen subshrub around 40-45 cm, it demands full sun and excellent drainage, is notably drought-tolerant once established, and draws hummingbirds and bees to its luminous blooms.

Mature size: 40-45 cm tall and 45-60 cm wide

Watch for — Winter wet / root rot: The chief killer—wet, poorly drained soil in winter rots the crown. Plant in gritty, fast-draining ground or raised beds; protect in cold, wet regions.

How to tell penstemon heterophyllus 'electric blue' needs repotting

Repotting on a calendar is less reliable than reading the plant. For penstemon heterophyllus 'electric blue', watch for these signs:

Roots growing out of the drainage holes, or the rootball lifting the plant proud of the rim.
Soil that has shrunk away from the pot sides and no longer holds water.
The pot is unstable because the plant has grown top-heavy.
Old, compacted, broken-down mix that stays wet too long — for a succulent that is a rot risk, so refresh it even if the pot size is fine.

For the underlying biology of a pot-bound root system and why it stalls a plant, see our guide to spotting and fixing a root-bound plant.

How often to repot penstemon heterophyllus 'electric blue'

Every 2–3 years, into bone-dry mix. Penstemon heterophyllus 'Electric Blue''s growth habit — low, bushy, semi-evergreen subshrub with a mounding to slightly spreading habit and slender blue-green leaves. — sets the pace. 'Electric Blue' is a Californian foothill penstemon famed for vivid gentian-blue, tubular flowers with violet tints over narrow blue-green foliage in early summer. A low, semi-evergreen subshrub around 40-45 cm, it demands full sun and excellent drainage, is notably drought-tolerant once established, and draws hummingbirds and bees to its luminous blooms.

What size pot to step penstemon heterophyllus 'electric blue' up to

Use a pot only one size up — or even the same pot with fresh gritty mix if the roots have room. Penstemon heterophyllus 'Electric Blue' stores water and rots in a large pot of slow-drying soil. A tight terracotta pot that dries fast is far safer than a generous plastic one. Never up-pot a succulent by several sizes.

Not sure of the exact diameter? Our pot size calculator takes the current pot and root spread and tells you the right next size — it deliberately recommends a single step up, never a big jump.

The best time of year to repot penstemon heterophyllus 'electric blue'

Spring or summer, while penstemon heterophyllus 'electric blue' is in active growth and warm, is best — roots recover fastest then, and the plant is not sitting in cool damp soil. Avoid repotting a succulent in winter dormancy.

Step-by-step: repotting penstemon heterophyllus 'electric blue'

Repot dry. Do not water penstemon heterophyllus 'electric blue' for several days first. Working with dry roots and dry mix dramatically lowers the rot risk for a succulent.
Pick a snug, fast-draining pot. Choose terracotta one size up at most, with a drainage hole. Have gritty very sharply drained, lean, gritty or sandy soil ready.
Tip it out and clean the roots. Slide the plant out, crumble off the old soil, and trim any black, mushy or dead roots with clean snips.
Pot into dry mix. Set penstemon heterophyllus 'electric blue' at its original depth in dry gritty mix, firming gently. Do not bury the stem deeper than it was.
Wait a week before watering. Leave it completely dry and out of harsh sun for about 7 days so any damaged roots callus. Only then water lightly.

Aftercare

Keep penstemon heterophyllus 'electric blue' completely dry and out of fierce sun for about a week so any nicked roots callus before they meet moisture; watering a freshly repotted succulent is the classic way to rot it. Then resume the normal lean, dry rhythm. Do not fertilise for about 3 weeks — fresh mix already carries nutrients and feeding freshly disturbed roots scorches them.

The right soil mix for penstemon heterophyllus 'electric blue'

Penstemon heterophyllus 'Electric Blue' wants very sharply drained, lean, gritty or sandy soil. Insists on fast drainage; it rots in heavy, rich or wet ground. Add grit on clay soils, or grow in raised beds, gravel gardens or containers. Always use fresh mix when you repot — reusing old, broken-down soil reintroduces the compaction and poor drainage you are repotting to fix.

Repotting penstemon heterophyllus 'electric blue' — frequently asked questions

How often should you repot penstemon heterophyllus 'electric blue'?

Every 2–3 years, into bone-dry mix for penstemon heterophyllus 'electric blue'. Repot penstemon heterophyllus 'electric blue' every 2–3 years into a snug pot of very sharply drained, lean, gritty or sandy soil, ideally in spring or summer. Let it sit in dry soil and do not water for about a week afterwards so any nicked roots can callus. Over-potting and watering straight away is what rots succulents.

What size pot does penstemon heterophyllus 'electric blue' need?

When is the best time of year to repot penstemon heterophyllus 'electric blue'?

Should you water penstemon heterophyllus 'electric blue' after repotting?

No — not straight away. Repot penstemon heterophyllus 'electric blue' into dry mix and wait about a week before the first watering so any damaged roots callus over. Watering a freshly repotted succulent is the single most common way to rot one.

Should you fertilise penstemon heterophyllus 'electric blue' after repotting?

Not immediately. Wait about 3 weeks after repotting penstemon heterophyllus 'electric blue'. Fresh mix already contains nutrients, and feeding freshly cut or disturbed roots burns them. Resume your normal feeding routine once you see new growth.