Tony Dickerson answers your questions
QIs my flowering velvet calathea unusual? Doreen Fletcher, by email
ACalatheas are grown mainly as foliage houseplants. There are over 300 species and they belong to the prayer-plant family Marantaceae, which are very popular and widely stocked by plant centres. Your plant is Calathea
rufibarba, known as the velvet calathea due to the soft covering on the underside of leaves. At 75cm (2½ft) it’s a good-sized specimen and this probably explains why it has flowered.
Generally, it’s unusual for calatheas to flower in domestic homes. The exception is Calathea crocata, the eternal flame plant, which is often seen for sale with spikes of orange flowers atop dark, metallic-green foliage. The main problem with most houseplants is that they don’t like conditions in our houses. Calatheas are native to the rainforests of South America, where they enjoy high temperatures, humid conditions and some shade. The latter is easy enough to achieve in our homes and so long as you can maintain a minimum winter temperature of 15C (59F) they’ll be warm enough. The real problem is that the atmosphere in our homes is usually very dry and foliage plants usually go brown along the leaf edges. The usual advice is to sit plants on trays of wet pebbles, but I’m not sure how effective this is, so I’d always opt for a daily misting of tepid water with a hand sprayer. While it can be difficult keeping these plants looking their best long-term, follow these guidelines:
From late spring to autumn keep plants well watered but never wet. Over winter, reduce watering but don’t let the compost get really dry.
Feed plants every two weeks with a liquid houseplant fertiliser when in growth, and never place them near a radiator.
Repot every couple of years in mid-spring using good quality multi-purpose potting compost.
Wipe the leaves occasionally with a damp cloth to remove dust or, in mild weather, put them outside with your other houseplants and use the watering can to give the leaves a good shower.
QIs it a good idea to recycle used plastic food containers to sow seeds in? Tom Leech, Warrington, Cheshire
AWe all want to cut down on plastic waste, but I’m not a fan of this type of reuse. Food tubs have flat bottoms and, even if you put lots of drainage holes in, when placed on a flat surface the water is held by surface tension, so they easily become waterlogged.
Different-sized containers are difficult to water accurately and quickly. I use rigid module (cell) trays or 10cm (4in) pots for most seed sowing. Most I have had for 10 years and some for more than 25. The downside is that you have to initially pay out more for robust containers.
If you buy in lots of plants in pots, ask day centres, residential homes and hospices that run gardening activities if they can make use of your unwanted pots.
QShould I plant my trees with John Innes po ing compost and bonemeal as recommended by the nursery I bought them from? Sheelah Stephens, Sandown, Isle of Wight
ATrees establish better with as little alteration of the natural soil as possible. Digging a hole and filling it with John Innes, especially on a clay soil, will simply create a sump where water will collect.
Cultivate a wide area, then throw the soil up into a low, wide mound no more than 15cm (6in) high. Plant into the top of this, ensuring you have teased out the roots well and have no more than 2½-5cm (1-2in) of soil over them.
There’s probably no point adding bonemeal – which contains phosphorus – as most gardens have no shortage of it. The one additive your new trees will benefit from is water! Apply a couple of watering cans on planting and then every seven to 10 days if no rain falls. Keep them weed-free and apply a general fertiliser next February.
QAre there other hardy mimosas similar to Acacia dealbata? Bob Wright, by email
AThere are nearly 1,000 species of acacia native to Australia and the surrounding islands. Most won’t grow outdoors in the UK. Even
Acacia dealbata – frost-hardy to -5C (23F) – can get caught by winter cold. It can grow to 10m (33ft), but kept pruned makes a great late-winter flowering tree and is the best one for chalky soils. ‘Gaulois Astier’ is more compact, growing to about 6m (20ft).
Most acacias don’t have true leaves like A. dealbata – they have phyllodes. These are flattened leaf stalks, adapted to dry climates.
Here are a few others worth trying in warmer, sheltered gardens. Most are half-hardy and will tolerate temperatures down to freezing.
l A. baileyana (Cootamundra wattle) makes a graceful shrub to 6m (20ft) with fern-like, silver-grey leaves and clusters of small, round, yellow flowers in late-winter. ‘Purpurea’ is a dark-leaved form, suited to a sheltered wall.
l A. paradoxa (kangaroo thorn) is small-leaved and prickly, making a dense, bushy plant to about 4m (13ft). Single, yellow flowers in spring.
l A. pravissima (Oven’s wattle) grows to 5m (16½ft). It has triangular, leaf-like phyllodes and small, rich yellow flowers in late winter.
l A. retinodes (wirilda) is a large, spreading shrub to 6m (20ft). It has narrow, lance-shaped, leaf-like phyllodes and impressive lemonyellow flowers in summer.
QHow do we look after our indoor cyclamen after it has finished flowering? Norma Krajewska, by email
AIndoor cyclamen are easy to keep from year to year if you follow a few golden rules. Ensure they have a brightlylit situation but away from direct sunlight. A cool hallway or room is ideal, but always away from radiators. Remove spent flowers by giving them a sharp pull. This avoids leaving stems behind which often rot. Occasional drying out of the compost is less harmful than overwatering, but always water from the top, never standing pots in water.
After flowering, continue watering and feeding with tomato fertiliser until the leaves yellow, then reduce watering as the plant becomes dormant for the summer. When new growth appears, replace the top compost in the container with fresh and resume regular watering.
QCan I prune my photinia ‘Red Robin’ without damaging its growth? Nicola Bowen, by email
A‘Red Robin’ produces brilliant red young foliage in spring. Pruning won’t damage the shrub but instead enhance the display for next year.
On a well-shaped plant you just need to shorten stems by about 15cm (6in) in mid-spring. You have a dozen or so rather straggly shoots, so I’d prune harder back to the main body of the shrub. On older, overgrown photinias it’s possible to renovate by pruning hard back to a framework of older branches lower down in spring. Regrowth during the first year is modest, but after that they leaf up nicely.