Need advice for garden border

[Prishan]

Dear Friends,
Greetings from Wales,
I would appreciate your valuable advice.
I would like to redecorate my border in the small front garden with newer flowering plants , I have already planted different roses
( 6 ), initially I thought to keep it with just roses. As the roses are not spreading or branching out that much, I need to fill the rest of border with other plants. I have brought chrysanthemums (6), Aquilegia (4),lavenders(6), and Asiatic lily(5).

My question is should I plant them in groups or can plant them randomly?

The border is like a half rectangle with its length 30'.7"'
and on each side it is 15'.8" ,
its like a half rectangle

The rose plants at the moment are each 2' feet apart
I am sending photos of the garden including the border along the pictures of the plants I collected.

I would be grateful, for your advice.

 

[Marck]

Very nice, this should be a colourful, flowery border. It appears sunny and well drained. There are endless possibilities, but we will only focus on the plants you already have selected. All these plants can be grown near each other, but do take placement into account.
Plant your Lavender (Lavandula angustifolia 'Hidcote') higher as it will prefer less water, and more drainage than some of the others. Conversely, the Columbine (Aquilegia cvs.) and Asiatic Lilies (Lilium Asiatic Hybrids, Division 1) should receive relatively more water, but still with good drainage. Place them near the front of the bed where they will give the best show when in bloom.
Loosely alternate your Chrysanthemum (Chrysanthemum morifolium cvs.) with the roses as they will be the next largest plant of those you selected. 'Mums' will be restful green mounds early and mid season but will carry the bed gloriously in autumn when other flowers have ended their show.