Start by sketching the tulip in your sketchbook or on a piece of cartridge paper, marking the veins as well as the outlines of the petals. Veins are visible and give texture to the tulip petals, so it is important to get them right. Trace the drawing and transfer to the watercolour paper. You can then go back to the sketch for a quick tone study. Daniel Smith Moonglow is a good colour to use for this. 

Once the line drawing is transferred to the watercolour paper, paint the shadows wet-in-wet, brushing following the pattern created by the veining, along the straight central veins and the curved side ones. You need to keep some shine on those petals, so make sure you mark the strong highlights on the sketch and reserve them carefully. 

The first colour to go down after the shadows is the magenta, or Quinacridone Lilac. This bright colour will shine through the subsequent dark layers of paint, giving light and life to the painting and stopping the dark mix looking flat. Before painting the back petals, mask the postil with masking fluid to make sure that the area stays clean, ready for the pale yellow.

Now that the masking fluid is protecting the pale centre, you can bring out the big brush to paint wet-in-wet washes more loosely and quickly. This is a size 12 soft synthetic brush that carries a lot of water and paint. Continue to add the magenta colour until every petal has an underlayer. 

I chose the small tepal on the left to test my dark purple mix. At the same time I made sure that my chosen method for creating the highlights gave the result I wanted: working wet-in-wet, painting with a strong colour and leaving a slice of wet but unpainted paper. 

When you are satisfid with the highlight and colour, it is time to work with the same technique on a larger scale, starting with the tepals at the back. Use a large brush to apply water and a small brush to drop in the colour so that it doesn't spread too far. First add the purple mix, then Perylene Violet while the purple mix is still wet. 

Usually I would paint the same number of washes on all the tepals, working in a balanced way through the painting. Because the colour of the tulip is so dark, the layering of multiple washes of dark paint is likely to encroach on the petals in front. In order to minimize the amount of painting lifting to tidy this up, I decided to almost finish the back tepals before starting on the other ones.

Still working from back to front, the next tepal is the middle one. If you have a large tepal in your flower, paint it in two parts, using the central veins as a separation. This will give you more time to work the wet-in-wet washes before the paint starts to dry. The first wash on the right half is more magenta with some Perylene Violet and some of the deep purple mix in the darkest parts, all dropped in while the paper is still wet.

The left half is darker towards the bottom. To get the darkness while keeping some intensity, wet the paper (including the highlight) then drip in some pure Phthalo Blue in the darkest areas and some magenta in the lightest. Leave this wash to dry, re-wet the paper and add the purple mix with some extra Perylene Violet added. Make sure you reserve the strong highlights all along the tepals. 

The tepals behind the masked area won't require any more wet-in-wet work. If they need more details or if more darkening is required, it will be with a dry brush. More wet-in-wet work now would risk lifting the previous washes. So, it is time to remove the masking fluid. Using a putty eraser to gently lift the fluid is a good way to do so without damaging the paper.

The reflected light at the bottom of the tepals does not require reserving the highlights in the same way as the main light does. This is because reflected light is never as bright as directed light. Lifting the paint while the wash is still wet is sufficient. A wet-in-wet wash of pure blue under the main colour allows you to get a dark wash without losing intensity.

At this stage, wet-in-wet washes are finished on the three back tepals, the masking fluid is gone and the centre is ready to be painted; the tepal on the right has three washes on top of the shadows, the stem has two wet-in-wet washes of a green mixed from yellow and he blue used in the shadows, and the petal at the front is finished on the left but has only one wash of colour on its right side.

Painting the centre

1. Wash in the shadow mix wet-in-wet with a size 2 brush.

2. Tidy up the edges where the masking fluid has left an uneven edge. Use the same colour directly behind any edge that needs help.

3. Paint the pistil with a diluted wash of yellow, dropping in a little bot of green along the style.

4. Start adding some black to the stamens, using the undiluted shadow mix. Add a touch of Magenta to the anthers and a bit of blue to the filaments.

5. Rub a 3/0 brush on the white pigment stick.

6. Stipple some white onto the black anthers to create the powdery effect of the pollen.

The left half of the most central front tepal is darker towards the bottom. To get the darkness while keeping some intensity, wet the paper (including the highlight) then drop in some pure Phthalo Blue in the darkest areas and some Quinacridone Lilac in the lightest. Leave this wash to dry, re-wet the paper and add the purple mix with some extra Perylene Violet added. Make sure you reserve the strong highlights all along.

This is the last wet-in-wet wash, so make it count. Drop in a lot of colour to boost up the intensity, Here, I started with the Quinacridone Lilac and dropped in some Perylene Violet while it was still wet.

Now all the wet-in-wet washes are done. There is a point where trying to layer more wet-in-wet work will start lifting the previous washes rather than adding more colour, especially with dark subjects, which have potentially thicker washes than pale ones. If adding more water to the paper for the next wet-in-wet wash starts lifting paint, it is time to move on to some dry-brush work. 

Time to add a bit more colour to the stem. Wet the whole stem and drop in some green under the tulip and down along the shadows. The green is mixed from the blue and yellow used in the Harmonic Shadow colour. Reserve a highlight down along the stem to give the rounded shape.

Last details such as veins are painted on dry paper, with a 3/0 brush. A larger brush is loaded with clean water. First draw a few veins with the small brush, then, before they dry, brush along with the larger brush gently so that it doesn't lift the paint and doesn't erase the veins. Painting the veins without blending them in results in the veins looking like a series of lines drawn onto the tepal rather than integrated into the texture.