How to Grow Geraniums from Seed

Quick Navigation

Use this list to jump straight to timing, sowing, seedling care, transplanting, and troubleshooting.

• Quick facts
• When to start geranium seeds
• Indoor sowing setup
• How to plant geranium seeds
• Seedling care
• Pinch for bushier plants
• Harden off and transplant
• Beds, containers, and window boxes
• Keep geraniums blooming
• Choose a geranium type
• Troubleshoot common problems
• FAQ
• Shop geraniums

Geranium Growing Quick Facts

Use these to set your calendar and manage expectations before the first seed goes in.

• Best start window: 12 to 16 weeks before your last frost date
• Seed depth: About 1/8 inch, barely covered
• Germination window: 7 to 21 days at consistent warmth — range is wide, so do not give up early
• Soil temperature for sprouting: 70° to 75° F; below that germination slows, above 78° F it can stop entirely
• Light needs: Full sun, at least 6 hours; longer sun means stronger bloom
• Bloom timing: Most types flower 13 to 15 weeks from sowing under good conditions
• Soil preference: Well-drained; geraniums will rot in soggy soil faster than almost any other bedding plant
• Hardiness: Tender perennials grown as annuals in most climates; not frost-tolerant

1. Know When to Start Geranium Seeds

Start geranium seeds 12 to 16 weeks before your last expected frost. That timeline feels long until you understand what the plant is doing: geraniums put a significant amount of energy into root and stem development before they flower, and there are no shortcuts that produce the same result.

If you start too late, you will set out seedlings that are behind and underdeveloped. They will bloom eventually, but you will lose several weeks of peak summer color. If you start on time and give them strong light throughout, transplant day looks like you are setting out blooming greenhouse plants, because you are.

Find your last frost date, count back 14 weeks, and that is your target sow date. In most of the mid-Atlantic and Midwest, that puts sowing in late January through February. In zones 9 and 10 where winters are short, earlier sowing gives you a long season.

2. Set Up for Indoor Sowing

Geranium seeds need consistent bottom heat and bright light from the moment they sprout. This is not a optional. Cool trays and dim windowsills produce slow, weak germination followed by leggy seedlings that never quite catch up.

A heat mat set to about 70° to 75° F under your seed trays makes a real difference, especially in late January or February when indoor temperatures swing overnight. A grow light positioned 4 to 6 inches above the seedling canopy once sprouts emerge keeps plants compact from the start.

Use a fine, well-drained seed-starting mix. Do not use garden soil or a heavy potting blend, both stay too wet, which is where geranium seedlings run into trouble fastest. Fill cells or a flat, water well, let it drain completely, and sow into soil that is moist but not saturated.

If you are reusing trays or cell packs from a previous season, wash them in soapy water first, then dip in a solution of one part chlorine bleach to nine parts water. Damping off is a persistent problem with geranium seedlings, and dirty containers are one of the most common ways it gets started.

Have a clear plastic dome or plastic wrap on hand to cover the tray after sowing. Keeping the humidity consistent during germination reduces the need to water frequently and helps hold soil temperature steady.

If you are still building out a seed-starting setup, Park Seed's guide on seed starting indoors covers the gear that matters and what you can skip.

3. How to Plant Geranium Seeds

Plant geranium seeds about 1/8 inch deep in a fine, moist seed-starting mix, then cover lightly and keep the surface consistently moist until sprouts appear.

Geranium seed is larger than many annuals and benefits from good seed-to-soil contact. Press gently after sowing so the seed is not sitting in an air pocket. Cover lightly, too much depth slows emergence. Some growers sow directly on the surface and press in rather than covering at all; either method works as long as the seed stays moist.

A few specifics worth knowing before you start:

• Sow one seed per cell if using trays; this avoids thinning later, which disturbs roots
• If sowing in a flat, space seeds about an inch apart so thinning is easier
• After sowing, water by partially submerging the container in a shallow tray of water and letting moisture wick up from below; this keeps seed in place and avoids packing the surface into a crust
• Cover the tray with a clear plastic dome or plastic wrap immediately after watering; remove it as soon as the first seedlings appear
• Check warmth first if germination is uneven; this is a much more common cause than bad seed

Germination timing varies more with geraniums than with most other annuals. Some seeds sprout in 7 days, others from the same packet take 21. Leave the tray set up and keep conditions steady. Late germinators catch up fast.

4. Give Geranium Seedlings What They Need

Strong light and good airflow are the two things geranium seedlings need most. Everything else is secondary.

When seedlings show their first true set of leaves, move them from the flat into individual containers. Handle them by the leaves, not the stems because geranium stems at this stage are thin and break easily. Set each seedling deep enough that the seed leaves (cotyledons) sit just at soil level. This gives the stem extra support and encourages strong root development.

Grow lights should be 4 to 6 inches above the seedling canopy. Closer than that can stress young growth; farther away produces the stretchy stems you are trying to avoid. Extend the time under grow lights to 14 to 16 hours per day. Plants grown only in a window often get tall and spindly because even a south-facing window rarely delivers the intensity a grow light does consistently.

Ideal growing temperatures are 70° to 75° F during the day and 60° to 65° F at night. The cooler nights keep growth compact and discourage soft, floppy stems.

Water carefully. The most common mistake with geranium seedlings is keeping the mix too wet between waterings. Let the surface begin to dry before watering again. Lift trays to feel the weight. Once you know what a properly moist tray feels like versus a saturated one, you will catch problems early.

If you are using a commercial potting mix that contains slow-release fertilizer, additional feeding probably is not necessary at this stage. For mixes without it, a half-strength balanced liquid feed every two weeks is enough to keep growth steady without pushing soft, leafy growth.

Thin ruthlessly if cells are crowded. Geraniums need air moving around the base of each stem, and crowded seedlings are where fungal problems start.

5. Pinch Seedlings Once for Bushier, Better-Branching Plants

Pinch geranium seedlings once they have 4 to 6 sets of true leaves by removing the growing tip just above a leaf node. This one step changes the shape of the plant for the rest of the season. Left unpinched, a geranium tends to run upright on a single stem and flower at the tip. Pinched once, it pushes two to four lateral shoots from below the cut and grows into a full, branching plant that carries more flower heads at once.

Use your thumbnail or a clean pair of scissors. Remove the top inch or so of the main stem, cutting just above a node where leaves attach. The plant will look set back for about a week. It is not. Growth resumes from the side shoots within 10 to 14 days, and by transplant time the difference between a pinched and unpinched seedling is obvious.

A couple of things worth knowing before you pinch:

• Wait until the plant has enough leaf sets that removing the tip does not leave almost nothing behind
• One pinch is enough for most seedlings; a second pinch on the resulting side shoots is optional if you want an especially dense plant and have time before transplant
• Pinching delays first bloom by roughly one to two weeks, which is an easy tradeoff given the fuller plant you get in return
• Do not pinch seedlings that are already stressed or recovering from poor light or cold; wait until they look sturdy

6. Harden Off Carefully Because Geraniums Feel the Difference

Plan on a full 10 to 14 days of hardening off for geraniums, longer than you would give most annuals. They have been growing in protected conditions for three months or more by transplant time, and the adjustment to outdoor wind, direct sun, and temperature swings is significant.

Start with an hour or two in bright, open shade on a calm day. Increase outdoor time gradually over two weeks, moving plants into more sun each day. The first time full afternoon sun hits leaves that have only ever seen grow lights, you will likely see some temporary bleaching or leaf curl. That usually resolves within a few days if you did not rush the transition.

Do not move geraniums out until nights are reliably above 50° F. Even a brush with 40° nights sets plants back noticeably and slows the first bloom flush.

7. Plant in Beds, Containers, or Window Boxes

Geraniums perform well in any well-drained situation, beds, containers, and window boxes, as long as roots are not sitting in moisture after rain.

In beds, space plants about 12 inches apart to allow for airflow and mature spread. Geraniums in a crowded bed are slower to branch and more susceptible to botrytis in a wet summer. In containers, choose pots with at least one large drainage hole and a potting mix that does not compact after a few weeks of watering. Window boxes reward the same drainage attention, a box that holds water after every rain will cost you plants before summer ends.

Use this spacing and placement when deciding what fits where.

Whatever the setting, geraniums planted into warm soil that drains freely settle in faster and branch more aggressively than those planted into cold, compacted ground.

8. Keep Geraniums Blooming

Deadheading spent flower heads at the stem, not just the petals, is the single most effective thing you can do to keep geraniums blooming. Pull or cut the entire flower stem down to the next leaf node. Leave the spent stem in place and the plant will not put energy into the next round of buds at the same rate.

Water deeply at the base, then let the top inch of soil dry before watering again. In containers during July and August, that cycle may mean watering every one to two days during heat. In the ground, longer intervals are usually fine as long as the rain does not fill the gap.

Fertilize lightly every two to three weeks with a balanced formula. High-nitrogen feeds push foliage at the expense of flowers. A balanced 10-10-10 or a bloom-promoting formula keeps the ratio right.

If plants get leggy in midsummer, cut stems back by about one-third and water in well. Geraniums branch from below the cut and often produce their best late-season show from stems that were trimmed in early August.

9. Choose a Geranium Type That Fits the Job

The most useful question to ask before choosing seed is whether you need upright plants for beds or containers, or trailing types for baskets and window boxes. After that, bloom color, petal form, and foliage pattern are the decision.

Park Seed carries four series worth knowing:

• Maverick Geraniums are a strong all-around choice for beds and containers — they produce large, bold flower heads on compact, well-branched plants and perform consistently through summer heat.
• Multibloom Geraniums live up to the name. The plants stay compact and carry an unusually high number of flower heads at once, which makes them especially useful for containers and window boxes where visual density matters.
• Pinto Geraniums are notable for early bloom and a wide color range. If you want flowering plants ready to go the moment you set them out, Pinto is worth a close look.
• Nano Geraniums are the most compact series in the lineup, topping out around 8 to 10 inches. They are the right choice for small containers, tight edging, or any spot where a standard-size geranium would crowd out neighboring plants.

If you are new to growing geraniums from seed, Maverick or Multibloom are reliable starting points. Both are forgiving of minor timing variations and give you a clear picture of what a well-grown geranium looks like at peak performance.

10. Troubleshoot Common Geranium Problems Early

Most geranium problems trace back to moisture management, light, or temperature. When you catch problems early, they are fixable.

Work through this list when something looks off.

• Poor germination: Check soil temperature first. Below 68° F germination slows dramatically; above 78° F it can stop. Old seed or seed that dried out during sowing can also cause this.
• Damping off (seedlings collapsing at soil line): Usually tied to dirty containers, wet soil, or poor airflow. Sanitize containers before reuse, let the surface dry between waterings, and keep air moving around seedling stems.
• Leggy seedlings: Almost always a light issue. Move grow lights closer or extend the photoperiod.
• Yellow leaves on seedlings: Often overwatering. Let the mix dry down more between waterings.
• Botrytis (gray mold): Shows up in cool, humid conditions with crowded plants. Improve airflow, reduce overhead moisture, and remove affected leaves immediately.
• Edema (corky bumps on leaves): Caused by irregular watering, especially overwatering in cool conditions. Not a disease — adjust watering and it resolves.
• Failure to bloom: Usually the result of too little sun, starting too late, or plants that never fully recovered from transplant stress.
• Leggy mature plants: Cut back hard, water in, and wait. Geraniums almost always recover from a midsummer trim.

If a planting looks healthy but lags behind, check light and drainage first. Those two variables account for the majority of geranium problems in home gardens.

FAQ: Growing Geraniums from Seed

Should I pinch geranium seedlings?

Yes. Pinching the growing tip once the seedling has 4 to 6 sets of true leaves produces a bushier, better-branching plant that carries more flower heads at once. It delays first bloom by one to two weeks, but the fuller plant is worth it. One pinch is enough for most seedlings.

How long does it take to grow geraniums from seed to bloom?

Most geraniums take 13 to 15 weeks from sowing to first bloom under good conditions. That is why starting 12 to 16 weeks before your last frost matters — you want blooming plants at transplant time, not seedlings.

Are geraniums hard to grow from seed?

They are not difficult, but they are slower and more light-dependent than most annuals. The main requirements are consistent bottom heat during germination, strong grow light exposure throughout the seedling stage, and patience with the timeline. Gardeners who have started tomatoes and peppers from seed will find the process familiar.

What temperature do geranium seeds need to germinate?

Geranium seeds germinate best at 70° to 75° F. Below 68° F, germination becomes slow and uneven. A heat mat under the tray makes a consistent difference, especially for late-winter sowing.

Why are my geranium seedlings leggy?

Leggy geranium seedlings are stretching toward inadequate light. Move grow lights to within 4 to 6 inches of the seedling canopy and extend the daily photoperiod to 14 to 16 hours. Seedlings that are leggy from the start rarely produce the stocky, branching plants you want at transplant time.

Can you direct sow geranium seeds outside?

Not practically in most climates. Geraniums need 13 to 15 weeks from sowing to bloom, which means outdoor direct sowing does not produce flowering plants until late summer in most zones. Start them indoors.

Do geraniums come back every year?

In zones 10 and 11, zonal geraniums can overwinter outdoors. In cooler climates, they are grown as annuals. You can overwinter container geraniums indoors. Bring them in before the first frost, cut back by about half, and keep them in a cool, bright location through winter.

Why did my geraniums stop blooming mid-summer?

Spent flower heads left in place, heat stress, irregular watering, and low-nitrogen soil are the common causes. Remove entire spent flower stems, water deeply and consistently, and apply a balanced fertilizer. In extreme heat, some varieties take a brief pause — they usually resume once temperatures moderate.

Shop Park Seed's full geranium seed selection, including Maverick, Multibloom, Pinto, and Nano series.