Seed Sowing Indoors (RHS guide)

Posted by editor on Saturday, 2 February 2019

Sowing seeds indoors allows tender plants to be started off earlier in the season. When they have grown into young plants, they can be planted outside in the garden or vegetable plot once the weather is warm enough.


The RHS website’s Guide to Seed Sowing Indoors:

Many vegetables, including tomatoes and runner beans, can be started off indoors. Some, like celeriac, need a long growing season to bulk up, so are best started off indoors rather than direct outdoor sowing. See RHS Grow Your Own for advice on growing specific vegetable crops.

Annual bedding plants, such as morning glory (Ipomoea), sweet pea (Lathyrus odoratus), marigolds (Calendula and Tagetes species) and sunflowers (Helianthus cultivars) can be started off indoors to create flower displays for the summer.

Some tender perennials, such as cannas, begonias and Diascia can also be sown from seed indoors, but generally take two years to reach flowering size. Perennials live indefinitely, so a slow start pays off in the long run!

If you have a heated greenhouse or enough space and light in the house, you can sow some things indoors as early as January (e.g. radish, chicory and sweet peas).

Otherwise, most crops and flowers are started off indoors in February or March, for planting out in May or June when the risk of frost has passed.


  • Small seeds are generally sown into shallow seed trays and pricked out (transplanted) into larger pots while still at the seedling stage.
  • Slightly larger seeds can be sown into individual modules in a modular plug tray, so limiting transplant shock.
  • Large seeds can be sown individually into 9cm (3.5in) diameter pots.
  • Old containers should be thoroughly cleaned before use.


  • Use a standard, proprietary soil-based or soil-less seed compost for seed sowing. These are finely milled and contain few nutrients, which could damage seedlings.
  • Fill the container with compost, level, firm gently and water well.


  • Many seeds require specific sowing treatments, such as light-exclusion or scarification (scratching or nicking the seed coat), so check seed packets for specific instructions.
  • Small seeds can be scatter-sown thinly over the surface of the compost. Very small seeds can be mixed with fine, dry sand before sowing to obtain an even distribution. After scattering, sift a layer of compost or fine vermiculite over the seeds.
  • Larger seeds can be station-sown, pressing each seed individually into the surface of the compost a couple of centimetres (1in) apart in a seed tray. If using a modular plug tray, sow one seed per plug. Sometimes, two seeds are sown per plug and the strongest seedling selected, discarding the weaker one.
  • Label, lightly water again and cover with clear polythene or a sheet of glass, or place in a heated propagator with a lid. Maintain a temperature of around 18ºC (64°F), unless seed packet states otherwise.

Aftercare and growing on:


  • Check daily for emergence. Once germination occurs, the glass, polythene or propagator lid should be removed to increase ventilation.
  • Keep the compost just moist at all times to maintain steady growth until the seedlings can be pricked out (transplanted) to bigger pots.

Pricking out

  • To prick out seedlings, loosen the compost around their roots with a blunt stick or ‘dibber’ and lift the seedlings individually by holding one of the true leaves (not the first seed leaves produced just after germination) between finger and thumb.
  • Try to keep as much compost around the roots as possible and use the dibber to make a hole for the seedling in its new pot of compost.
  • Pot each seedling into a 9cm (3.5in) diameter pot. If the seedlings are leggy, bury them slightly deeper (up to the first pair of leaves) in their new pot.

Plug plants

  • Seeds sown into modular plug trays can be left without pricking out until their roots fill the compost in each module. Small plugs need individual potting on into 9cm (3.5in) diameter pots. Larger plugs may become substantial enough to plant directly into hanging baskets or display tubs.

Growing on

  • Water small seedlings and plug plants with a watering can fitted with a fine rose, to avoid damaging them. Larger seedlings and more mature plugs can be watered using a coarse rose, as flooding is necessary to soak the entire depth of compost and roots.
  • Feed pricked-out seedlings and plug plants with a balanced liquid fertiliser applied fortnightly in most cases. Larger plants may need weekly applications and tiny seedlings may only need monthly feeding.
  • If sowing into larger plug trays, try putting controlled release fertiliser granules or a chicken manure pellet in the bottom of the plug before sowing to provide plants with nutrients as their roots grow down into the compost.
  • If ornamental seedlings become lanky, pinch out their shoot tips to encourage branching. If necessary, several ‘pinchings’ can be done before the plant is ready to go outside. Avoid excessive legginess by growing plants in bright light and avoiding overly warm conditions.

Hardening off

  • Once the weather is warm enough and plants are large enough to be moved outside, they will need gradual hardening off to outdoor conditions.



Snowdrop time!

Posted by editor on Wednesday, 16 January 2019

Snowdrops usually nod their delightful heads at the earliest around mid-February; however the unprecedented earliness of snowdrops these past few years has inspired us to remind you that now is the time to increase your collection of these lovely early spring plants.

One of our favourite Sussex nurseries is Marchants Hardy Plants, which at this time of year offers a fine collection of ‘snowies’ or Galanthus if we’re being formal (Greek gála “milk”, ánthos “flower”).



Marchants is a thriving perennial /grasses nursery where renowned plantsman Graham Gough says: “I have grown snowdrops affectionately for over 35 years, 18 of them here at Marchants. We are not ‘twin scalers’, more hobbyists and our principal concern has been to add good garden worthy snowdrops to our collection. As bystanders we have looked upon the Snowdrop revolution with amusement as well as bemusement. With irony too – have you noticed how over the years, the more unlike a snowdrop a plant becomes the greater its price tag increases. At its most serious level this has become a hobby for very deep pockets!”

Marchants do not offer a mail order service, so pre-ordering is essential.  Visit the nursery on 26th January (10am – 4pm) . CLICK HERE for mail-order list and more information.

Graham writes about the cultivation of snowdrops:

“Snowdrops are not difficult to grow but it is worth observing a few rules of thumb. They do not enjoy dense shade, nor do they like stagnant, badly drained soil. Good drainage is therefore a must. Acid or lime soils seem to make little difference – they can flourish on both. That said, they prosper on thin chalk soils, encouraging for those of you who garden on this hungry type of soil. Dappled shade can also be advantageous though many Snowdrops will also prosper in full sun. The fact is they are very amenable and associate well with virtually all late winter and early spring flowering plants.

When your bulbs begin to clump (3/4 years), you can then increase your stock by dividing them. Clumps left to their own devises can  ‘go back’ or worse still, die out altogether. Division usually takes place when plants are ‘In the green’, during or after flowering  (though most books will tell you to do it after). We have noticed little difference. Having gently teased a clump apart, it is important to plant at the same depth or deeper if the bulbs have risen to the surface, adding a little bone meal /seaweed meal to help give your snowdrops a good re-start. On heavy soils the addition of sharp grit is efficacious. Any remaining nurture should be left to Mother nature. Lastly, always label your snowdrops well. Push labels into the soil in front of and behind your clumps. You then have two reference points.”



Wrapping and Rolling!

Posted by editor on Thursday, 29 November 2018

Now is the time to tackle those critical early winter tasks before the really cold weather comes in.  Firstly get more shrubs for free without the need for a glasshouse or heated propagators by taking your own hardwood cuttings (it’s so easy) and protect your most sensitive plants or risk losing them to the coming frosts

Take hardwood cuttings from deciduous shrubs such as Salix, Cornus, Buddleias and Philadelphus, and from fruit bushes such as gooseberries and black currants as well as rambling and climbing roses.

After leaf fall take pencil thick cuttings, about 25cm long of new growth – you can insert them directly into the soil or – our favourite method – use an empty compost sack or thick black polythene to make a roll as in the picture.  Add some perlite for drainage and make holes in the bottom of the roll to stop water from collecting there and causing them to rot.

Stand your cuttings in the corner of the garden and wait for them to root, check them every couple of weeks to make sure they are not drying out- Cornus and Buddleia will root quickly but other shrubs make take a few months.

If you can’t lift your tender plants and take them into a greenhouse there are many ways to protect them in situ.   Wrap with horticultural fleece, cover with cloches or bigger leaves, or making simple structures.  We took these photos, below, at Nymans Gardens at Handcross where the gardeners regularly employ all these methods to put their tender plants to bed before the winter rain, frost and snow.






We love Asters: Late Summer Colour!

Posted by editor on Tuesday, 9 October 2018

This year’s extraordinary (maybe even becoming normal?) late summer sunshine reminds us that we can continue to enjoy colour in the garden well into October and even early November.

Here at The Garden House we have many late summer perennials still in bloom – Asters, Hardy Chrysanthemums, Japanese anemones, Crocosmias, Salvias, Penstemmon, Dahlias, Sedums and more – and annuals such as Cosmos, Persicaria orientalis, Cleome, Coreopsis and Ageratum are still enthusiastically flowering.

Many of these are in the hot colour spectrum, adding yet more fire to the Indian summer temperatures – pink, red, orange and yellows – and are perfectly supported by a variety of wonderful late summer grasses, such as miscanthus and panicum, which add structure and movement to mixed plantings.  Also the prettier softly tufted grasses such as Lagurus ovatus ‘Bunny’s Tails’ look great interplanted between annuals.

Shrubs such as Pyracantha, Cotoneaster and Cornus mas are also full of fiery coloured berries at the moment.


Save the Date – come to our MacMillan Coffee Morning!

Posted by editor on Tuesday, 18 September 2018

Visit the Garden House and support the World’s Biggest Coffee Morning, Macmillan’s fundraising event for people facing cancer. All over the UK people will be hosting their own Coffee Mornings and donations on the day are made to Macmillan. Last year alone MacMillan raised £29.5 million and this year they are aiming to raise even more.

Join us on Friday 28 September 2018 in the autumn garden and enjoy coffee and delicious handmade cakes. We will also be selling refreshments, plants, jams and chutneys. Invite your family and friends – what better way to catch up and support this worthwhile cause!

Open 11am to 3pm. Entry: £2 / children free.

Location: The Garden House, 5 Warleigh Road, Brighton BN1 4NT.