How Long Do Vegetables and Herbs Take to Grow? A Beginner's Timeline
- The Royal Horticultural Society says salad radishes can be ready in as little as four weeks, although early spring sowings take six to eight.
- University of Maryland Extension gives 7 to 21 days from sowing to harvest for microgreens and 21 to 40 days for baby salad leaves.
- Fruiting crops such as tomatoes need 6 to 8 hours of direct sun a day, while lettuce and other cool-season leaves manage on 3 to 5 hours.
- Sowing a small batch every two to three weeks gives a steady supply and means there is always something close to harvest.
- Most early failures come from too much water or too little light, and both are easy to check before you sow anything.
The most common reason a first pot of seeds ends up in the bin is that nobody said how long it would take. A tomato sown on a windowsill in March will not feed you until July at the earliest.
Garlic planted in October is still sitting there the following June. If you expected results in a fortnight, that feels like failure. It is the normal schedule.
This guide gives realistic seed-to-harvest times for the crops that suit pots, balconies and windowsills, checked against the Royal Horticultural Society and US university extension services. It also covers the two mistakes that kill most first attempts, and how to arrange your sowing so that something is always nearly ready.
How long does each crop take from seed to harvest?
The table runs from fastest to slowest. Times are from sowing (or planting, for garlic and potatoes) to the first harvest in decent conditions. UK timings are by month.
US timings are given relative to your last spring frost or first autumn frost. A calendar date cannot do the job, because one that works in USDA zone 9 in California is two months too early in zone 4 in Minnesota.
| Crop | Sowing to first harvest | When to sow in the UK | When to sow in the US |
|---|---|---|---|
| Cress and microgreens | 1 to 3 weeks | Any month, indoors | Any time, indoors |
| Pea shoots | 3 to 4 weeks, cut at 10 to 15 cm (4 to 6 in) | Any month, indoors in bright light | Any time, indoors |
| Salad radishes | About 4 weeks in warmth; 6 to 8 weeks for early sowings | Spring, early summer and late summer | Early spring, then again from late summer. Midsummer heat makes them hot and woody |
| Cut-and-come-again salad leaves | About a month in summer; around two months in cool weather | Indoors from February, outdoors from mid-spring to late summer | Spring and autumn outdoors; indoors under lights at any time |
| Salad onions (scallions) | About 2 months | Outdoors from March | From early spring |
| First early potatoes | As little as 12 weeks from planting | Plant around late March | Early spring. Your state extension service publishes local planting dates |
| Peas for pods | About 12 weeks for early varieties, 14 to 16 for maincrops | Spring | Early spring, while it is still cool |
| Tomatoes | Roughly 4 to 5 months | Late March to early April for outdoor plants; plant out in early summer | Start indoors 5 to 6 weeks before planting out, which is after the last frost |
| Chillies | Roughly 5 to 6 months | Indoors from late winter to mid-spring, at about 21°C (70°F) | Indoors in late winter; plant out well after the last frost |
| Garlic | 7 to 9 months | Plant mid-autumn to early winter; lift late spring to early summer | Plant a week or two after the first killing frost; lift late June to late July in the northern states |
The figures come from the RHS grow-your-own guides for radishes, salad leaves, tomatoes and garlic, alongside University of Minnesota Extension pages on radishes, tomatoes and garlic. The tomato and chilli rows are my arithmetic from the RHS sowing and harvest months, since the RHS does not give a single number. The garlic figure is the same kind of sum.
Basil deserves a line of its own. Sown between March and July, it can be cut as a microgreen within 10 to 14 days according to the RHS basil guide, but a plant big enough to pick from repeatedly takes a good deal longer, and it sulks below about 10°C (50°F) at night.
Why is mine slower than the seed packet says?
Seed packet times assume good conditions: warm compost, long days and steady moisture. A windowsill in February has none of those. The RHS puts the gap in plain numbers for salad leaves, which take about a month in summer and a couple of months when it is cool. The same doubling applies to most leafy crops.
Temperature sets the pace at the start. Tomato seed wants around 18°C (64°F) and usually comes up within a fortnight. Chillies want about 21°C (70°F). On a cold sill in an unheated room, seeds can sit for three weeks doing nothing visible, and the usual response is to water them again, which makes things worse.
Light sets the pace afterwards. University of Maryland Extension gives 6 to 8 hours of direct sun for warm-season crops such as tomatoes and peppers, and 3 to 5 hours for cool-season leaves such as lettuce and spinach. A north-facing balcony will grow salad. It will not ripen a beefsteak tomato, however patient you are.
Why do beginners give up, and how do you avoid it?
Two causes account for most of it. The first is water. New growers water on a schedule, or whenever they feel anxious, and roots sitting in saturated compost run out of air. The RHS houseplant guide is blunt: "Don't water routinely, check that the pot needs water first."
Its method is to push a finger a few centimetres into the compost, or lift the pot, since a dry pot is noticeably lighter than a wet one. Either check takes five seconds and saves more seedlings than any product.
The second is light. University of Minnesota Extension states that "lack of light is the major cause of elongated, skinny stems" in seedlings, and goes as far as saying a windowsill is not a good place to start seeds in a northern spring.
In practice that means sowing later than you think and turning trays daily. It also means choosing crops that match the light you have.
| What you see | Likely cause | What to change |
|---|---|---|
| Tall, pale seedlings that flop over | Too little light, often combined with too much warmth | Move to the brightest sill, turn the tray daily, sow later in spring or add a basic LED grow light |
| Yellowing, wilting leaves in wet compost | Overwatering. The RHS lists wilting, yellowing and leaf drop as signs, along with dark, mushy roots | Stop watering until the top few centimetres are dry. Empty saucers. Check the pot has drainage holes |
| Seedlings that collapse at soil level | Damping off, a fungal problem of wet, still conditions | Sow thinly, water from below, improve air flow and start again with fresh compost |
| Radishes that are all leaf, or hot and woody | Slow growth from heat, drought or crowding | Sow in spring or late summer, thin to a few centimetres apart and keep evenly moist |
| Healthy tomato plant, no ripe fruit by September | Sown too late, or fewer than 6 hours of direct sun | Next year buy a young plant in May, choose a cherry variety and give it your sunniest spot |
A third cause is less technical. People start with the slowest crops because those are the ones they most want to eat. A first year built on tomatoes, chillies and aubergines (eggplants) means three months of looking at leaves. Put a tray of something fast beside them.
What does a first season look like week by week?
Here is a worked example for one sunny windowsill plus a doorstep or balcony, starting in the first week of April in the UK, or about two weeks before your last frost date in the US. It uses five crops and costs little more than five packets of seed and a bag of peat-free compost.
| Week | What you are doing | What you are eating |
|---|---|---|
| 0 | Sow cress in a shallow tray of compost, pea shoots and salad leaves in trays, radishes in a 30 cm (12 in) pot, and tomato seed in small pots indoors | Nothing yet |
| 1 to 2 | Tomato seedlings appear. Sow a second tray of cress | Cress |
| 3 to 4 | Sow a second tray of salad and a second pinch of radish seed | Pea shoots, more cress |
| 5 to 8 | Move tomato seedlings into bigger pots. Keep sowing salad every two to three weeks | Radishes, first cuts of salad leaves |
| 9 to 10 | Plant tomatoes into their final 30 to 45 cm (12 to 18 in) pots outside once nights are reliably mild | Salad, second radishes |
| 16 to 22 | Feed and water tomatoes. Stop sowing lettuce in the hottest weeks if it bolts | Tomatoes, from around late July into September |
The point of the example is the right-hand column. There is no gap longer than a fortnight without something to cut, even though the headline crop takes four months. That is the whole trick to staying interested.
What is succession sowing, and how often should you sow?
The RHS defines successional sowing as making repeated sowings of a crop, usually in small batches every two to three weeks, to give a continuous harvest and avoid gluts. It suits anything quick: salads, radishes, salad onions, spinach, peas and French beans.
It matters most for crops that bolt, such as coriander (cilantro), rocket (arugula) and spinach, because each batch has a short useful life. The calendar is only a rough guide. The RHS suggests lettuce might need sowing every three weeks in early spring and as often as weekly in warm, moist summer weather.
A more reliable cue is the previous batch. Sow the next lot of leaves when the last lot has about four true leaves, and the next peas when the last are about 5 cm (2 in) tall.
In a small space, "a batch" is tiny. Half a seed tray of salad, or ten radish seeds in a 30 cm pot, is plenty for one person. A full packet sown at once produces forty radishes in the same week and none for the rest of the summer.
What should you do while you wait?
Very little, and that is harder than it sounds. Most of the damage done to young plants is done by attention: extra water, a move to a warmer spot, a poke to see whether the seed has sprouted. A few jobs are useful and keep your hands busy.
- Write the sowing date and the expected harvest date on every label, so that week three of nothing is visibly on schedule.
- Check moisture with a finger each morning and water only the pots that are dry a few centimetres down.
- Turn windowsill trays a half-turn daily so seedlings grow straight.
- Sow the next small batch of something fast every two to three weeks.
- Move seedlings into a bigger pot when roots show at the drainage holes.
- Keep a one-line log of what you sowed and when it cropped. Next year's timings will come from your own sill, which beats any table, including the one above.
If the wait for fruiting crops is too long, shorten it honestly. Buying a young tomato or chilli plant in May skips the first two months, and there is no rule that says everything must start from seed.
Questions readers ask
What is the fastest vegetable to grow from seed?
Cress and other microgreens, which the RHS says show results in one to three weeks and which University of Maryland Extension times at 7 to 21 days. Among crops grown to full size, salad radishes are quickest at about four weeks in warm weather. Both will grow in a container, and microgreens need only a tray on a bright windowsill.
Why have my seeds not come up?
Cold is the usual reason. Tomatoes need about 18°C (64°F) and chillies about 21°C (70°F) to germinate, and an unheated sill in early spring can be well below that at night. Old seed and waterlogged compost are the other common causes. Give most vegetable seed three weeks in warmth before writing it off.
Is it too late to start in summer or autumn?
Rarely. The RHS lists late summer as a sowing time for salad radishes and salad leaves, and hardy salad onions can go in during late summer and early autumn for a spring harvest. Garlic is planted from mid-autumn to early winter. Microgreens and pea shoots can be sown indoors in any month.
Can you speed plants up?
Only by fixing what is slowing them. Warmth speeds germination, more light speeds growth, and steady moisture keeps radishes and salads moving. Extra fertiliser on a seedling that is short of light produces a taller, weaker seedling. The practical shortcut for slow crops is to buy young plants.
Sources
- Royal Horticultural Society. Grow-your-own guides: radishes; salad leaves; salad onions; peas and pea shoots; potatoes; tomatoes; chilli peppers; garlic; basil. Accessed September 2026.
- Royal Horticultural Society. Growing microgreens. Accessed September 2026.
- Royal Horticultural Society. Successional sowing. Accessed September 2026.
- Royal Horticultural Society. How to grow houseplants; How to help a poorly houseplant. Accessed September 2026.
- University of Maryland Extension. Growing microgreens and baby greens indoors; Growing vegetables in containers. Accessed September 2026.
- University of Minnesota Extension. Growing radishes; Growing tomatoes; Growing garlic in home gardens. Accessed September 2026.
- University of Minnesota Extension. Starting seeds indoors. Accessed September 2026.
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