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Ornamental Grasses

Updated: May 2, 2023

Ornamental grasses are among the most versatile plants you can have in the garden. They run the gamut from towering over your head to just a few inches tall. Some types need lots of sun and others don't mind some shade. Lots of ornamental grasses offer four seasons of interest. These are some of the best varieties to try in your yard; you'll especially love how they look and sound when rustling gently in a breeze. So whether you need to add a bit of shape and texture to a border, or a stand alone in a pot, grass has got you covered.

Feather Reed Grass

A very popular ornamental grass, offering a distinct upright habit that looks fantastic all winter long. Like many grasses, this is a tough plant that tolerates a wide range of conditions. Perfect for the UK climate.

Name: Calamagrostis 'Karl Foerster'

Growing Conditions: Full sun and well-drained soil

Size: To 6 feet tall

Fountain Grass

A beautiful, mounding plant, fountain grass has a graceful shape, plus soft, feathery plumes that dance in the breeze.

Name: Pennisetum alopecuroides

Growing Conditions: Full sun and well-drained soil

Size: To 5 feet tall

Little Bluestem

As beautiful as it is hardy, little bluestem

offers gray-green leaf blades that turn bold shades of purple, red, and orange in autumn.

Name: Schizachyrium scoparium

Growing Conditions: Full sun and well-drained soil

Size: To 3 feet tall

Switch Grass

A North American prairie native, a delicate grass that offers airy plumes in late summer and fall. Many varieties (such as 'Dallas Blues') offer blue-gray foliage during the season and turn brilliant shades of gold and red in autumn.

Name: Panicum virgatum

Growing Conditions: Full sun or part shade and well-drained soil

Size: To 5 feet tall

Blue Oat Grass

It's tough to beat blue oat grass for a low care plant with steel-blue colour. It also has a tidy mounded habit and won't spread and take over your garden.

Name: Helictotrichon sempervirens

Growing Conditions: Full sun and well-drained soil

Size: To 4 feet tall

Purple Millet

Incredibly tough annual grass offers fantastic burgundy foliage and rich purple foliage that look like fuzzy cattails. Also attracts birds to the garden.

Name: Pennisetum glaucum

Growing Conditions: Full sun or part shade and well-drained soil

Size: To 5 feet tall

Cord Grass

An underutilised perennial, cord grass is a spreading prairie grass that thrives in moist or wet soils. It's a good choice for growing next to your pond.

Name: Spartina pectinata

Growing Conditions: Full sun and moist soil

Size: To 7 feet tall

Japanese Forest Grass

Japanese forest grass has a nearly-perfect mounding habit. Variegated selections (such as 'Aureola') have brightly coloured foliage.

Name: Hakonechloa macra 'Aureola'

Growing Conditions: Part shade and well-drained soil

Size: To 1 foot tall

General Care and Maintenance

Plant Spacing

As a good rule of thumb is to space plants proportionate to how tall they are at maturity. For example, if the plant will reach 1 meter at maturity, plant them 1 meter apart. For larger varieties like Cortaderia (pampas) place plants 2 m (6ft) apart.

  • Plant height 50-100cm (20-40in) -recommended 6 plants per linear meter

  • Plant height 100-150cm (40-60in) -recommended 4 plants per linear meter

  • Plant height 150-200cm (60-80in) -recommended 3 plants per linear meter

  • Plant height 200-250cm (80-100in) -recommended 2 plants per linear meter

  • Plant height 250-300cm (100-120in) –recommended 1-2 plants per linear meter

  • Plant height 300-350cm (120-140in) –recommended 1-2 plants per linear meter

Ground Preparation

  1. It is always best to measure twice and cut once, so use planning line and canes to plot out your location. Start by removing all turf above the immediate area before planting.

  2. Remove all vegetation from the immediate planting area before you begin digging.

  3. Using a gardening fork, till up the soil thoroughly twice as deep as container the plant was shipped in. If available, you can also use a petrol/electric powered tiller. This is important as uncultivated soil can restrict plant growth and not let the roots establish. Make sure and remove any large rocks.

Day of Planting

Plant your new Ornamental grass

  1. Place a landscaping tarp parallel to the planting area and dig an area twice as wide as the nursery container and just as deep, place soil on the tarp after removal. If necessary, use the container itself as a guide. For Cortaderia (Pampas) Dig holes that are 3 times as deep and wide as the root ball to encourage spreading.

  2. Mix the native soil that is to be backfilled 1-1 with Planting Compost. If you have heavy soil and drainage is a problem, consider amending with Horticultural Grit.

  3. Carefully remove the plant from the pot and break up the bottom edges of the root-ball taking care to unfurl and tease out the roots from the base so that they will establish in the soil. Tap the side of the pot with your hand if the root-ball is being stubborn and will not remove easily. Then gently place the plant upright into the hole, packing the surrounding soil around the root ball to keep the plant in the desired position make sure to plant at the root line.

  4. Water the soil around the plant thoroughly, make sure the soil is very moist but don’t use so much water that puddles form. Water bi-weekly for the first month and weekly for the next two months. Subsequent watering should only be necessary during extended dry spells.

Container Planting

  1. Make sure the pot is wide enough to accommodate arching grass blades and has proper drainage. A lighter, unglazed pot will evaporate excess moisture better than darker, glazed pots.

  2. Cover the drainage holes with a screen to prevent clogging. Mix through horticultural grit with your substrate, do not put a layer of grit at the bottom. All This does is create a layer of stagnant water which is ready to rot the roots.

  3. Use a 1-1-1 mix of Planting Compost, Horticultural Gravel, and native topsoil to ensure the plant has proper nutrition and drainage.

  4. After removing the plant from the nursery container, plant at root-ball depth and pack the surrounding area with 1-1-1 mix. Pack firmly enough for positioning, but not so tight that root growth is restricted.

  5. Water thoroughly after planting until water comes out of the drainage holes but do not waterlog. Consider raising the container off of the ground with feet to mitigate any clogging and help with drainage. This will also help keep your pots from cracking in the frost.

Ornamental Grass Trimming Advice

There are two main categories of Ornamental Grasses; evergreen and deciduous. While deciduous grasses will need to be cut back annually, evergreens will just need to be trimmed up.

Deciduous Grasses

  • Some varieties like Cespitosa Goldtau need to be trimmed all at once at 3cm (1in) above ground level before growth start in early spring (mid-March to April). Prune Miscanthus at the same time, but individually remove the shoots with secateurs so as not to sever the newly forming green shoots.

  • While Stipa Tenuissma is classified as deciduous, it will tend to have evergreen traits in some gardens. If there are low amounts of dead material building up, simply comb out the loose foliage as you would an evergreen. If it takes deciduous traits and foliage dies off uniformly, fully cut back in spring.

Evergreen Grasses

  • Do not cut back evergreen varieties like Carex (Sedges) all at the same time. Cut off spent stalks and individually remove diseased or unsightly leaves. Evergreens lose leaves periodically throughout the year.

  • Cortaderia (Pampas) does benefit from hard pruning in early spring. Cut back vigorously, but take care not to damage new growth. Wear eye protection and gloves, leaves can be sharp. Use loppers to sever stubborn stems.

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