Learn About Portulacas
How to Sow
How to Sow and Plant
Portulaca may be grown from seed sown early indoors and transplanted outside after frost, or sown directly in the garden after frost.
Sowing Seed Indoors:
- Sow indoors 6-8 weeks before the last frost in spring using a seed starting kit
- Sow seeds 1/8 inch deep in seed starting formula
- Keep the soil moist at 70-75 degrees F
- Seedlings emerge in 10-14 days
- As soon as seedlings emerge, provide plenty of light on a sunny windowsill or grow seedlings 3-4 inches beneath fluorescent plant lights turned on 16 hours per day, off for 8 hours at night. Raise the lights as the plants grow taller. Incandescent bulbs will not work for this process because they will get too hot. Most plants require a dark period to grow, do not leave lights on for 24 hours.
- Thin to one seedling per cell when they have two sets of leaves.
- Seedlings do not need much fertilizer, feed when they are 3-4 weeks old using a starter solution (half strength of a complete indoor houseplant food) according to manufacturer’s directions.
- Before planting in the garden, seedling plants need to be “hardened off”. Accustom young plants to outdoor conditions by moving them to a sheltered place outside for a week. Be sure to protect them from wind and hot sun at first. If frost threatens at night, cover or bring containers indoors, then take them out again in the morning. This hardening off process toughens the plant’s cell structure and reduces transplant shock and scalding.
Sowing Directly in the Garden:
- Direct sow seeds in average soil in full sun after all danger of frost.
- Choose a location in full sun with very well-drained soil.
- Prepare the soil by removing weeds and working organic matter into the top 6-8 inches of soil; then level and smooth.
- Most plants respond well to soils amended with organic matter. Compost is a wonderful form of organic matter with a good balance of nutrients and an ideal pH level, it can be added to your planting area at any time. If compost is not available, top dress the soil after planting with 1-2 inches of organic mulch, which will begin to breakdown into compost. After the growing season, a soil test will indicate what soil amendments are needed for the following season.
- Sow seeds thinly and evenly and cover with 1/8 inch of fine soil.
- Firm soil lightly with your hand, water and keep evenly moist.
- Seedlings will emerge in 10-14 days.
- Portulaca may be grown closely together and usually does not need to be thinned.
How to Grow
- Keep weeds under control during the growing season. Weeds compete with plants for water, space and nutrients, so control them by either cultivating often or use a mulch to prevent their seeds from germinating.
- Mulches also help retain soil moisture and maintain even soil temperatures. For annuals an organic mulch of shredded leaves lends a natural look to the bed and will improve the soil as it breaks down in time. Always keep mulches off a plant’s stems to prevent possible rot.
- Portulaca is drought tolerant, but plants need about 1 inch of rain per week during the growing season. Use a rain gauge to check to see if you need to add water. It's best to water with a drip or trickle system that delivers water at low pressure at the soil level. If you water with overhead sprinklers, water early in the day so the foliage has time to dry off before evening, to minimize disease problems. Keep the soil moist but not saturated.
- Until plants become established, some protection from extreme winds and direct, hot sunlight may be necessary. Good air movement is also important.
- After new growth appears, a light fertilizer may be applied. Keep granular fertilizers away from the plant crown and foliage to avoid burn injury. Use low rates of a slow release fertilizer such as Flower-tone, as higher rates may encourage root rots.
- Remove spent flower heads to keep plants flowering until fall.
- Monitor for pests and diseases. Check with your local Cooperative Extension Service for pest controls recommended for your area.
- Remove plants after they are killed by frost in fall to avoid disease issues the following year.
- Portulaca is ideal for containers. Take care not to overcrowd them or the flowers may be significantly smaller than they should be and the plants may be taller. Always use a commercial potting mix, do not use garden soil, and make sure the containers have adequate drainage. Container grown plants will require extra water and fertilizer, look for signs of wilt or a nutrient deficiency.
- Portulaca is perfect for rock gardens and for beds and borders in drought-prone areas. It grows nicely between paving stones.
- The plants have a spreading habit, so they cascade gracefully from hanging baskets and window boxes.
- They also make a great annual groundcover.
- Portulaca often will self-sow. If you want it to do so, allow some seed to ripen on the plant at the end of the season.
Common Pests and Problems
Damping Off: This is one of the most common problems when starting plants from seed. The seedling emerges and appears healthy; then it suddenly wilts and dies for no obvious reason. Damping off is caused by a fungus that is active when there is abundant moisture and soils and air temperatures are above 68 degrees F. Typically, this indicates that the soil is too wet or contains high amounts of nitrogen fertilizer. Burpee Recommends: Keep seedlings moist but do not overwater; avoid over-fertilizing your seedlings; thin out seedlings to avoid overcrowding; make sure the plants are getting good air circulation; if you plant in containers, thoroughly wash them in soapy water and rinse in a ten per cent bleach solution after use.
Root Knot Nematodes: Microscopic worm-like pests that cause swellings (galls) to form on roots. Plants may wilt or appear stunted. This is a serious problem in many Southern states. Burpee Recommends: Do not plant into infested soil. Try planting ‘Nema-Gone’ marigolds around your plants.
Root Rots: A number of pathogens cause root rots of seedlings as well as mature roots. Burpee Recommends: Practice crop rotation and do not plant related crops in the same area for several years. Pull up and discard infected plants. Make sure your soil has excellent drainage. Contact your Cooperative Extension Service for recommendations. Keep plants healthy.
White Rust: White rust cause branches and leaves to swell. Raised pustules can form on the front as well as the back of leaves. Branches can be deformed, erect and spindly. Burpee Recommends: Remove infected plants. Contact your Cooperative Extension Service for recommendations.
Common Pest and Cultural Problems
Aphids: Greenish, red, black or peach colored sucking insects can spread disease as they feed on the undersides of leaves. They leave a sticky residue on foliage that attracts ants. Burpee Recommends: Introduce or attract natural predators into your garden such as lady beetles and wasps who feed on aphids. You can also wash them off with a strong spray, or use an insecticidal soap.
Mealybugs: Mealybugs are 1/8 to ¼ inch long flat wingless insects that secrete a white powder that forms a waxy shell that protects them. They form cottony looking masses on stems, branches and leaves. They suck the juices from leaves and stems and cause weak growth. They also attract ants with the honeydew they excrete, and the honeydew can grow a black sooty mold on it as well. Burpee Recommends: Wash infected plant parts under the faucet and try to rub the bugs off. They may also be controlled by predator insects such as lacewings, ladybugs and parasitic wasps. Check with your Cooperative Extension Service for pesticide recommendations.
Scale: Small bugs look like brown, black, gray to white bumps on the stems of plants. Scale may not have any apparent legs and may not move. Scales have a sucking mouth part. Scale may produce a honeydew so leaves and stems may be sticky. Scale can weaken the plant causing it to grow very slowly and it may wilt at the middle of the day. Burpee Recommends: Completely spray the stems with Insecticidal soap. For a severe infestation contact your local County Extension Service for recommendation for your area.
Spider Mites: These tiny spider-like pests are about the size of a grain of pepper. They may be red, black, brown or yellow. They suck on the plant juices removing chlorophyll and injecting toxins which cause white dots on the foliage. There is often webbing visible on the plant. They cause the foliage to turn yellow and become dry and stippled. They multiply quickly and thrive in dry conditions. Burpee Recommends: Spider mites may be controlled with a forceful spray every other day. Try hot pepper wax or insecticidal soap. Check with your Cooperative Extension Service for miticide recommendations.
Thrips: Thrips are tiny needle-thin insects that are black or straw colored. They suck the juices of plants and attack flower petals, leaves and stems. The plant will have a stippling, discolored flecking or silvering of the leaf surface. Thrips can spread many diseases from plant to plant. Burpee Recommends: Many thrips may be repelled by sheets of aluminum foil spread between rows of plants. Remove weeds from the bed and remove debris from the bed after frost. Check with your Cooperative Extension Service for pest controls.
Should I start my portulaca indoors or outdoors? Portulaca may be sown directly in the garden or started early indoors. If you would like earlier bloom you can start them inside six to eight weeks earlier than direct sowing after danger of frost.
Is portulaca drought tolerant? Yes portulaca can tolerate drought and full sun conditions.
Can you tell me why my portulaca is not blooming? Make sure portulaca is planted in full sun; if it is planted in shade it may not bloom. Also, too much fertilizer can cause portulaca plants to have bright beautiful leaves and no flowers. Portulaca does not like too much fertilizer.
What is Moss Rose? Moss Rose is another common name for portulaca.
Why do my portulaca flowers close up during the day? Older varieties tend to have flowers that close during the brightest time of the day. Newer varieties such as Sundial mix stay open longer.