Speedwell can successfully be grown in containers. They can be grown as single plants for impact or they can be combined with other summer bloomers to make fantastic seasonal displays in large planters. Sunny decks and patios are the preferred spot for Speedwell to bloom profusely all season long. Potted Speedwell will need only slightly more attention than a plant growing in the ground. The smaller cultivars are better suited to container growing than the large types, which can get very top heavy while in full bloom.
Planting Speedwell in Pots
Planting perennials in pots is best done as early as the plants are available in the nurseries–typically early spring. The container needs to have plenty of drainage holes in the bottom and should be positioned where it can receive rain water. Be careful not to place pots near a downspout, where they could be flooded, or on a surface with standing water. The right choice of pot material will depend on what gardening zone you live in. Plastic and resin composite pots are more likely to withstand the freezing and thawing of cold winters than more delicate terracotta and glazed pottery.
Best Soil For Speedwell in Pots
All-purpose potting soil is lightweight and well draining, and works well for most containers. Soil from your garden or a bagged top soil will be too heavy and may compact around the drainage holes, eventually restricting drainage. Adding rocks to the bottom of the pot will not increase drainage and can limit the amount of moisture available to the roots.
Water will stay trapped under the layer of rocks or gravel, positioning the root ball on top of a perched water table. Lightly mulching the top of the pot will help keep the soil moist and cool in the summer. The mulch can be organic material that will decompose or more decorative river rock, glass chips, or even marbles to give the pot a modern look.
Caring For Speedwell in Planters
Perennials in pots have more requirements than plants in the ground. The plants in pots are at the mercy of the gardener and will need to have consistent watering, fertilizing, and winter care.
Watering Speedwell in Pots
Speedwell planted in a container needs far more water than if it was planted in the ground. Before watering, always assess if the plant is dry first. Usually, drooping flower stems or foliage is a giveaway that more watering is needed.
Depending on pot size, watering will need to be checked every day during the height of summer. Smaller pots will dry out faster than larger planters. Pots will need to be watered when the top two inches of potting soil are dry to the touch. Soak the pot until water runs from the bottom drainage holes, ensuring that all of the soil is well saturated. The best time to water is early in the day, which reduces the amount of evaporation from the soil. At other times of the day, water carefully so that minimal spray hits the leaves. Wet leaves late in the day or evening will be more prone to mildew and fungal attacks.
Fertilizing Speedwell in Pots
Fertilizing will need to be done on a monthly basis for Speedwell in pots. Most all-purpose potting soils do not contain much fertilizer. Even brands with added fertilizer will eventually lose nutrients over time through regular watering. Use a diluted liquid fertilizer once a month to support heavy blooming and good root development. Look for a fertilizer that has higher P (phosphorus) and K (potassium) numbers, which will promote blooms instead of excess foliage.
Winter Care For Speedwell in Pots
Speedwell is a hardy perennial that needs little protection to survive winters in the ground. Potted Speedwell may need more protection depending on your hardiness zone. Pots provide less insulation than the soil in the ground. Thus, potted plants should be treated as less hardy than plants in the ground. Moving pots to a less exposed position is the best way to keep them safe for the winter.
Wrapping the outside of pots in a couple layers of burlap will be suitable if the container is not able to be moved. Ensure that the pot continues to drain well through the winter. Pots sitting in water will eventually rot the roots. Placing pots up on bricks or ‘pot feet’ will assist in drainage, or you can move the pot to a drier spot for the rest of the winter.
Growing Speedwell Indoors
Speedwell is an herbaceous perennial that goes dormant for the cold winter months. There is no reason to bring the plant indoors for the winter. Speedwell requires cold exposure to enter dormancy and to prepare for the next growing season.
Author Robbin Small - Published 7-22-2022