How to Grow and Care for Broom Plants

Broom plants are small- to medium-sized shrubs with evergreen or deciduous foliage that grow quickly in a lax, bushy habit. Leaves are green and small, usually lanceolate. The two main species that share the common name broom are Cytisus and Genista. Both look very similar. The main difference is that Genistas are more tolerant of lime in water and soil.

Broom plants bear pea-like flowers in shades of yellow that attract pollinators. Cultivars and hybrids in a wide range of other flower colors are also available.

Broom plants are toxic to humans, and toxic to pets. If you decide to plant a broom, which can be done in the spring or fall, be aware that depending on where you live, certain broom species might be classified as invasive.

Broom Plant Care

Broom plants come in varying heights and colorful displays. Setting aside concerns about the invasive nature of brooms, their landscape uses are quite versatile. For example, brooms display pops of color in the spring and summer which can contrast nicely when planted in front of other green shrubs. Taller varieties of brooms can be planted as a hedge or border. The dwarf varieties of brooms look beautifully nestled as mass plantings in a rock garden.

Broom plants like workable, well-draining soil in open, sunny locations. The plants will tolerate wind, poor soil, drought, and rocky soil and are overall low-maintenance.

Light

Brooms grow best in an open area with full sun, though they will tolerate some shade. Follow the light and location directions for the specific variety. Overall, too much shade tends to make broom plants leggy with fewer blooms.

Soil

Establish in well-drained loam or poor soil (clay, sand, or loam). Acidic soil is best. Cytisus dislikes alkaline/chalky soils and Genista tolerates lime more easily. Broom can thrive in poor soil, through drought and neglect, and can even fix the nitrogen in the soil with fibrous, fast-growing stabilizing roots.

Mulch alkaline soil in the spring with ericaceous compost.

Water

Water regularly for the first few months if there is not enough rainfall to keep the soil moist. Maintain moisture in its first year to establish roots. Give an inch of water each week during its first summer and during heat or drought. Let the soil dry out between waterings.

Broom benefits from habitual watering if the location is dry and the soil is poor.

Temperature and Humidity

Broom performs best in conditions that would cause many other flowering shrubs to fail. It will bloom as early as late winter and through the early spring months in the cool temperatures of USDA Zones 8-10. Temperatures between 35 and 60 degrees Fahrenheit during the autumn and winter months encourage blooming.

Apply a 2-inch layer of lightweight shredded bark mulch to keep the roots cool and the soil moist. This will also provide a layer of insulation against the hot summer sun. Make sure the mulch doesn't touch the base.

Fertilizer

Broom thrives even in poor soil, therefore fertilizer is usually not necessary.

Broom Types

There are numerous broom species, cultivars, and hybrids. Popular ones include:

Cytisus Varieties

• Cytisus x kewensis (Kew broom) reaches 2 feet tall and is ideal for rock gardens. This wide, low-growing shrub displays pale yellow to creamy white flowers in spring.
• Cytisus x spachianus (sweet broom) is a hybrid with bright yellow, sweetly fragrant flowers in late spring.
• Cytisus x 'Lena' (Lena scotch broom) a dwarf variety that grows 4 feet tall. Foliage is deep green and flowers are ruby red and yellow through spring and early summer.
• Cytisus x praecox (Warminster broom) is a hybrid that grows to 5 feet tall offering pale yellow flowers in early May.
• Cytisus scoparius (common broom, Scotch broom) puts on a long show of yellow flowers on its 5-foot reach from May to June. There are several cultivars of the species. 'Cornish Cream' has ivory cream and yellow flowers. 'Goldfinch' is crimson and yellow with pink and yellow wings. 'Killiney Red' is a smaller, compact variety with red blooms. 'Burkwoodii' reaches between 5 and 7 feet tall, with crimson flowers in late spring.
• Cytisus racemosus nana (dwarf yellow broom) reaches about 5 feet in height and also grows well in containers. It has so many yellow flowers from spring to summer they nearly cover the whole plant.

Genista Plant Varieties

• Genista lydia (Lydian broom) grows 2 feet tall and spreads 3 feet. Its green arching stems are covered with golden yellow flowers in May and June.
• Genista hispanica (Spanish gorse) reaches 3 feet tall and spreads at least 7 feet wide. Golden flowers cover this dense, spiny shrub in June and July.
• Genista aetnensis (Mount Etna broom) grows 10 feet tall and spreads 8 feet wide with linear leaves and yellow flowers that bloom in July.

Pruning

This low-maintenance plant usually does well without pruning, but because many brooms have relatively short lives, pruning can extend their line span. There are slight differences in pruning Cytisus and Genistas.

Pruning Cytisus

Prune Cytisus varieties every year after they have stopped flowering.

When pruning Cytisus racemosus, timing is of the essence. Flowers appear on old wood and pruning at the wrong time could prevent or delay blooming. Prune in late spring or summer after bloom season is over. Do not prune in autumn or winter. Give the plant enough time to produce mature wood so that it will flower in spring again. Use very sharp, sterilized pruning shears to cut the plant back by a third. Cut each time at a 45-degree angle. Cutting straight across will cause the stem to hold rainwater and rot. 

Pruning Genistas

Pruning of Genistas depends on the variety so it is crucial for proper pruning to know which variety you have. For example, Genista aetnensis can be cut back quite a few times each season to encourage bushy growth. Genista hispanica can be lightly sheared after it is finished flowering. Genista lydia, on the other hand. does not need to be pruned at all.

Propagating Broom Plant

Broom has a deep, branched taproot that resents being disturbed. This rules out division as a propagation method but you can grow the plant from cuttings:

1. In July or August, using a sharp knife or pruners, take 3-inch healthy cuttings of semi-mature wood below a leaf node. Don't take cuttings any earlier or they may not root.
2. Dip the bottom in rooting hormone. Insert the cutting in a 4-inch pot filled with moist, well-draining potting mix.
3. Place the pot in a cold frame and keep it moist. The cuttings should have developed roots by the spring. Plant them promptly before the roots grow too deeply.

How to Grow Broom Plant From Seed

Broom seeds may be erratic to germinate. Also keep in mind that if you collect seeds from a cultivar, you will not get a plant that is true to the parent. If you still want to try growing broom from seed, here's how it's done:

1. In March or April, soak seeds in warm water for about 24 hours before sowing.
2. Use pots or flats filled with sandy soil. Plant the seeds 3/4 inch deep.
3. Keep the pots at 65 degrees degrees Fahrenheit indoors or outdoors depending on your climate. Germination time varies; Scotch broom takes up to four weeks to germinate.
4. Plant the seedlings the spring without much delay because the roots will grow long and the plant does not do well when transplanted at a late stage.

Potting and Repotting

For container growing, choose a smaller or dwarf variety. Choose a pot large enough to accommodate the root ball of the plant plus 6 inches to allow for future growth. Make sure the pot has large drainage holes. because the plants do not like wet feet. Fill it with well-draining lightweight potting mix.

When the roots fill the container or grow out of the drainage holes, is it time to repot the plant to a larger container.

Overwintering

Broom does not need any winter protection when planted in the ground, In potted broom, on the other hand, the roots are not sufficiently protected. Insulate the roots by wrapping the container in burlap and bubble wrap, or place it in an insulating silo for winter protection.

Common Pests & Plant Diseases

Webworms are the most common issue to look out for. They tend to overwinter in old debris, so rake the area around the plant completely clean. Broom plants are also susceptible to gall mites, an attack caused by fungus dieback; it will result in stunted growth, which is sometimes desired where the plant is considered invasive.

How to Get Brooms to Bloom

Brooms often don't bloom until the second or third year. If a mature plant fails to bloom, it is usually due to pruning at the wrong time and accidental removal of the flower buds. The other reason could be lack of sunlight. Broom needs full sun to bloom.