Filling in gaps

Hello, this is our first post here. Mum and daughter! We'll get gardening again soon for the spring.

We have a long border in a small back garden which is filled with evergreen shrubs and herbaceous perennials. Pittosporum, Hebes, lots of Heuchera, Lavender, Tiarella, Alliums, dwarf buddleja, Verbena bonariensis, Astilbes. The colour scheme is roughly purples and whites, or at least it started out that way when we designed it.

Some years it looks better than others and some plants have come and gone and been replaced, but there's usually some gaps between plants and often fairly big gaps when you look from the front. I love the look of borders that are bursting with colour and stuffed full of plants and it would be nice to achieve this.

Id really like to hear other people's recommendations of what they fill gaps with? Does anyone fill them at all? Put a few bedding plants in? Or I'm thinking what I could grow now from seed or buy and divide and keep in the greenhouse? I've only managed to think of Antirrhinum from seed that's fairly reliable. We try to attract bees and butterflies with what we plant. Soil is a fairly heavy clay.

I've got a few New England Asters in the greenhouse, about 12, that were propagated last autumn that could be popped in somewhere but probably closer to the back because of the height. The border is only about 6ft at the back.

So hello everyone thank you for taking the time to read our question and would love to hear other people's ideas for fillers

 

Welcome to the forum @OrangeHeart

Your border sounds colourful but it would help to have some more information so that our answers are useful rather than random suggestions. Thanks for telling us your soil is heavy clay. It would also be useful to know the aspect (is it south facing or ?, Shaded by trees or buildings?) and also whereabouts you are as advice for Surrey will be different to that for Scotland.

My soil is fairly heavy loam and Vebena bonariensis tends to be very short lived for me, it self seeds but behaves more like and annual/biennial than a perennial. I also find lavender very short lived as my soil is too rich and moist. Alliums, other than sphaerocephalon, only last a year or two as well, again the soil is too heavy. I suspect you may have the same issues?

 

Hello @Butterfly6 thank you for your reply.
Ive put on pictures. One is probably the best it's looked, but a few years ago now and the other picture is what the bed looks like close up really. I know there's still spring to come but it's looking a bit unkempt and sparse.

It's south facing but with mature trees on the opposite side so they cast shade. Which in summer to be fair is very welcome. It's on a slope so the bottom of the bed can get very wet. Tiarella has been the only thing to survive at the bottom (that's the most shaded part too) and Astilbe a bit further up but still in the damper area.

In the north of England.

Yes, short lived would be a good way to describe some things. The alliums are all spheracephalon, but last year I had to replace them all with new bulbs. The bees love them but they failed to come up properly. Instead of flourishing as the years go on and getting established the plants often just seem to go the other way, but this year I'd really like to make an effort. We landscaped it all ourselves from nothing a few years ago so it's a bit of a labour of love but it would be good to have it looking it's best and get some wildlife back in.

 

I think you’ve done an excellent job with your border @OrangeHeart. I like the rhythm you have created by repeating plants and using a controlled amount of colour. Your second photo will probably be matched by most borders in gardens across the country at this time of year! For fillers I tend to avoid annuals as they can attract slugs and snails. Perhaps some small upright evergreen grasses or sedges like Carex or Stipa tenuissima might be an option. Or you could introduce a contrasting colour such as orange, yellow or red, using upright perennials like Heleniums or Echinaceas, or maybe a couple of repeat flowering roses.

 

I hadn't considered annuals and attracting slugs and snails. I think I'll avoid them. I have enough slugs!

Don't really like the yellows and reds, or roses I'm afraid but thank you for the suggestion. I want to keep the whites / purple theme but it's included some shades into pinks. Echinacea I love but it just won't grow in this soil. Salvia won't either and Agastache too. Grasses are something I'd not considered and not had before, blue fescue might be nice it always catches my eye on the garden centres. Some things really struggle in the soil.

The veronicastrum initially did quite well but like other things it's gone sparse and weedy over the years

 

Lythrum might be something for you to try. It likes moist soil, is upright, a magenta shade of pink, flowers for a long time, bees love it and the bare stems look good over winter.

 

I really like that, thanks for that suggestion. Loosetrife? Is that in your garden @Plantminded?

 

Yes, purple loosestrife, a native wildflower. L. Dropmore Purple is a good variety. Yes, that’s the sunniest part of my garden .

 

Oh it's lovely thank you for sharing. Your garden is so well kept and neat. I really like the structure the shrubs give too.

I think that's another plant for us to consider then. It's so nice to get suggestions of things you wouldn't think of yourself.

 

Just a thought but if things have gone straggly over the years you could try dividing them? I've no idea about Veronicastrum as I haven't grown it.

 

That's probably a mid - back of border plant? Is it about 4ft in height the loosetrife? I'm happy to hear any ideas for something small too that could sit closer to the front in with the Heuchera. That's sort of where I was thinking about putting in temporary things like aubretia or lobelia

 

If you’re open to pinks then some of the persicarias would be worth looking at as they are tolerant of wet and dry soils. Persicaria affinis Superba is semi evergreen, quite low growing so a good ground cover. The Persicaria amplexicaulis varieties are good for summer height, they die down in winter. Quite a few to choose from so worth googling.

 

L. Dropmore Purple can get to about 1.5m, but there are shorter varieties, Robert, Little Robert and Robin at about 60-90cm.

For front of border, Carex varieties or Ajuga might suit.

 

Hello OrangeHeart, your border looks lovely, even at a grim time of year. One thing to consider is foliage, as well as flowers, as the foliage is there for such a big part of the year. Actaea (Cimicifuga) simplex has a few cultivars with lovely purple foliage and white or pale pink flower spikes. It likes damp soil. Campanula glomerata superba and Salvia nemerosa Caradonna are perhaps in the right colour range and the less than enticing foliage can be chopped down, the plants fed and watered to get another crop. The same goes for Aubretia. It's a perennial and if given a good haircut after flowering at least makes an attractive mat of silvery green foliage. Arabis is similar but tidier, flowering in purple, pink or white. Both the latter will do better with a bucketful or two of a sand or grit and compost mix incorporated into the soil before planting. ETA: Some of the hardy geraniums tick all the boxes. Verbena venosa (hastata) is a smaller, perennial cousin of V. bonariensis. It was very well-behaved in UK, turns out to be a runner here, but will grow anywhere IME!

 

I agree with using hardy geraniums, bees love ours, and they are slug proof (even in last summer's decimated borders!), some are semi-evergreen. The choice is a bit mind-boggling, but definitely worth a look. I’ve had to move some that are too tall/straggly for their spot though, so I’m starting to hunt for alternatives.

I just did a quick search and found the following (I couldn’t work out how to add the quote to this message, sorry!)