Inspired by a helpful YouTube guide. We based this walk-through on David Domoney's video "David Domoney Answers The Top Agapanthus Questions!". David is a Chartered Horticulturist and regular on ITV's Love Your Garden, so his answers tend to cut straight to what actually works in UK conditions. Worth watching before you plant - he covers the pot vs ground question in detail.
1. Choose the sunniest spot you have
Agapanthus flower best in full sun. A south-facing wall, a bright patio, or an open border that gets the sun from mid-morning through to evening - that is where they belong.
They will tolerate partial shade but flowering drops off noticeably. If you are planting in a shadier garden, choose a deciduous variety and accept you may get fewer flower stems. Sun really is the main driver.
2. Decide: pot or ground?
Both work, but the approach differs. In a pot, agapanthus actually like to be slightly root-bound - crowded roots seem to trigger more flowering. Go for a pot only a little larger than the root ball and resist the urge to pot on too soon.
In the ground, they need good drainage above everything else. Heavy clay that sits wet over winter will rot the roots. If your soil is clayey, work in plenty of grit before planting, or raise the bed a little. Sandy soil - which is common around Sandwich - suits them well.
3. Plant at the right depth
The rhizomes - the fleshy underground stems - should sit just below the soil surface, around 5–8cm deep. Too deep and they may not flower; too shallow and frost can get them more easily.
Plant in late spring once the worst of the cold has passed. Space plants around 30–45cm apart in the ground, or one per large pot. Water in well after planting and then leave them to settle.
4. Know which type you have: hardy or tender
This matters a lot for winter care. Deciduous agapanthus (which lose their leaves in autumn) are generally hardier and will often survive outdoors in Kent with no protection. Evergreen types are more tender and need covering or moving under cover when temperatures drop.
If you are not sure what you have, treat it as tender until it proves otherwise. A label on the plant or a quick search of the variety name should tell you. Most garden centre plants are labelled - check before you buy.
5. Feed and water during the growing season
From late spring through to midsummer, a balanced liquid feed every fortnight encourages good growth and decent flower stems. Switch to a high-potassium feed (like tomato food) from midsummer - this helps ripen the growth and sets the plant up for next year's flowering.
Watering: keep pots consistently moist in the growing season but not sodden. In the ground, established plants are reasonably drought-tolerant once they are settled. Young plants in their first year need more attention.
6. Deadhead spent flower stems but leave the foliage
Once a flower head has faded, cut the stem down to the base. No need to collect the seeds unless you want to try growing from them - it takes several years to get a flowering plant from seed, so most gardeners just deadhead and move on.
Leave the leaves in place until they die back naturally. They are still feeding the rhizomes. Cutting green leaves back early weakens the plant for the following year.
7. Protect tender types over winter
Pot-grown agapanthus: move them into a cold greenhouse, conservatory, or sheltered shed once temperatures drop below about 5°C. They need cool but frost-free conditions - a heated room is too warm and can push them into growth at the wrong time.
In the ground: mulch around the base with a thick layer of bark or straw once the leaves have died back. In East Kent the winters are rarely savage, but a sudden hard frost on unprotected crowns can cause damage.
8. Divide clumps every few years
Over time, pot-grown plants outgrow their containers and flower less. Clumps in the ground spread and the centre can become congested. Every three to four years, lift and divide them in late spring.
Split the rhizomes with a sharp spade or knife. Each division needs a decent chunk of root and at least a couple of growing points. Replant at the same depth, water in, and they should settle quickly. You will end up with more plants to spread around or pass on to neighbours.
When to call a handyman
Agapanthus growing is a gardening job, but if you need raised beds building, patio areas laying, or garden borders dug and prepared, Richard can help across Sandwich and the surrounding East Kent area.
Need help with your garden?
The Sandwich Handyman can help with raised beds, patio work, garden clearances, and general outdoor upkeep across Sandwich, Deal, and nearby East Kent villages.
Contact Richard