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Lentils take somewhere between 90 and 110 days from sowing to a crop ready to pull, depending on how cool the spring is. The sequence is short and inflexible: germinate in cold soil, grow through the damp part of spring, flower for two to three weeks, fill pods for another three or four, and then dry standing in the bed for two or three weeks before you pull the lot.
That last stage is the one everything else serves. Pod drying needs dry, warm, airy weather, and if it collides with a humid or rainy spell the crop molds on the plant. Since you cannot move the weather, you move the sowing, which is why lentils go in three to five weeks before the last frost rather than at the comfortable moment when everything else is being sown.
The calendar below is written by stage rather than by month, so it reads the same in either hemisphere. Work backwards from your own humid season: count back roughly 100 days from when you expect settled dry weather, and that is when the seed should go in.
| Stage | Trigger | What to do | What can go wrong |
|---|---|---|---|
| Bed choice | Before sowing | Pick the poorest, best-drained, sunniest bed with no legume for three years | Rich or wet ground gives soft growth, lodging and root rot |
| Sowing | Soil workable and above 40F (4C), three to five weeks before last frost | One inch (2.5 cm) deep, seed every one to two inches (2.5 to 5 cm), rows six to eight inches (15 to 20 cm) apart | Sowing late pushes drying into humid weather |
| Emergence | Seven to twelve days after sowing | Net against birds until plants are three inches (8 cm) tall | A stripped row does not recover |
| Early growth | Two to six weeks after emergence | Weed hard, add no feed, water only if the surface bakes | Weeds bury a small slow plant; feed makes it flop |
| Support | Plants four to six inches (10 to 15 cm) tall | Twiggy sticks through the block or string at eight inches (20 cm) | Support added later cannot lift a leaning stand |
| Flowering | Small pale flowers along the stems | One deep soak if dry. Check tips for aphids twice a week | Drought now aborts flowers and empties the pods |
| Pod fill | Flat green pods swelling | Leave the crop alone. Water only in prolonged drought | Flat pods mean heat or water stress at flowering |
| Drying in the bed | Lower leaves yellow, pods turning tan | Stop watering completely. Check daily for shattering | Rain now molds pods and can sprout seed in the pod |
| Pulling | Two thirds to three quarters of pods tan | Pull whole plants onto a sheet in the morning, bundle loosely, move under cover | Waiting for the last pod loses the first ones to shattering |
| Curing and threshing | One to three weeks under cover | Dry until seed will not dent, beat in a sack, winnow with a fan | Jarring damp seed leads to mold in storage |
The three moments that decide the crop
Most of this calendar is undemanding, and a lentil block will look after itself for weeks at a time. Three moments carry nearly all the risk, and knowing which they are lets you ignore the rest with a clear conscience.
The first is the sowing date. Sow early into cold soil and everything downstream falls into place. Sow at the comfortable time, when the soil is warm and you are sowing beans, and the pods will be drying in your muggiest weather. The second is putting support in while the plants are still short. It takes twenty minutes, and it is the difference between a stand you can pull cleanly and a mat lying on wet soil. The third is choosing the day to pull, which is a judgement about how much shattering you are willing to accept in exchange for a few more ripe pods.
Everything else, the weeding and the occasional watering and the aphid washing, is ordinary garden work that can slip by a few days without consequence. Concentrate your attention on the three that cannot.
- Count back 100 days from your settled dry weather That date, or the first day after it that the soil is workable and above 40F (4C), is your sowing day. It will feel too early, which is the point.
- Diarise the support job at three weeks after emergence Plants will be four to six inches (10 to 15 cm) tall. Put sticks or string in then, whether or not the stand looks like it needs it yet.
- Start checking pods daily once the lower leaves yellow From that signal, the pull date is usually one to two weeks away and the exact day depends on the weather. Daily checks stop you missing it.
- Pull at two thirds tan if rain is coming An early pull with some green pods beats a ripe crop rained on. The green pods finish ripening on the plant under cover.
- Do not jar the seed until it will not dent The thumbnail test is the last gate in the season. Everything you did over 100 days is undone by sealing seed at 15 percent moisture.
Where lentils fit in the rest of the garden
Because the crop occupies poor ground for a single season and finishes in mid to late summer, it slots in where little else wants to be. A thin, stony, free-draining bed that grows disappointing brassicas will grow a perfectly good lentil block, and the ground comes out of it better than it went in.
Leave the roots in the soil when you pull, or cut at the base and leave the roots if pulling brings them up. The nodules hold fixed nitrogen that releases as they break down, and the following crop in that bed notices it. Chop the threshed straw and return it to the same ground as well. Grown purely as a soil improver on a neglected corner, with the seed saved for next year's sowing, a lentil patch pays for itself even before you count what is in the jar.
The bed is usually clear by mid to late summer, early enough for a fast follow-on crop of salad or leafy greens that will appreciate the nitrogen. Just remember the three-year rule: no legume back on that ground until two full seasons have passed, so mark the bed on whatever plan you keep.
The record that makes the second year better
Six entries cover the whole season: the sowing date, the emergence date, the first flower, the day the lower leaves started yellowing, the pull date, and the cleaned seed weight against the area sown. Written down as they happen, they turn a novelty crop into something you can plan, and they answer next winter's question about whether to grow it again with a number rather than a feeling.
Add two notes alongside them. Record whether the block lodged and after what weather, because that decides whether you need denser sowing, earlier support or a more sheltered corner. And record what the weather was doing in the fortnight before you pulled, because if the drying stage keeps colliding with rain, the fix is a fortnight earlier at sowing and nothing else.
Keep the bed position on the same note. It matters for the three-year rotation, and it also matters because lentils leave the ground in good heart and you will want to know which corner is due the benefit.