The succulent, tasty leaves of homegrown spinach are beyond compare, but spinach can be a struggle for some gardeners to grow. Spinach is particular about its growing conditions and knowing when to harvest spinach can mean the difference between a big harvest and a minuscule one. In this article, I’ll offer tips on when to harvest both baby greens and mature leaves for a long 3- or 4-season harvest. I’ll also teach you how to overwinter spinach plants for an extra early spring harvest.
When to plant spinach: 3 great options
Before we talk about when to harvest spinach, it’s important to understand when to plant it. This is because the timing of the planting directly connects to the timing of the harvest. There are three times for planting spinach in growing regions that have four distinct seasons. The three planting times are:
1. Very early spring
2. Late summer or early fall, and
3. Late fall through mid-winter
Here’s how the timing of each of those three planting times affects when the spinach is harvested.
- Spinach seeds or transplants planted in the very early spring, about 8-10 weeks before your last expected spring frost (early March here in Pennsylvania), will germinate within a few weeks and produce a late spring harvest.
- Spinach planted in the late summer or early fall produces a late fall crop that can be harvested in the late fall or early winter. This crop can also be overwintered (you’ll learn how to do that later in this article) for a winter or an early spring harvest.
- If you plant spinach seeds in the late fall through mid-winter (anytime from a few weeks before the first frost to a few weeks after it), the seeds will sit dormant in the soil all winter long and germinate very early the following spring. This will yield an early to mid-spring harvest.
As you can see, for those of us in a temperate climate with four distinct seasons, it’s possible to be harvesting spinach almost year-round!
Can you grow spinach in the summer?
This is a tricky question. Since spinach dislikes summer’s extreme heat, spring-sown plants covered with a shade cloth or with a layer of lightweight row cover can be harvested through the early part of the summer. As the days grow longer and the temperatures rise, however, spinach bolts (goes to flower) and the harvest stops. Shading the plants can extend the harvest by a few weeks. If you want to try to harvest spinach in the summer, plant bolt-resistant and/or heat-resistant varieties like Palco, Seaside Hybrid, Olympia, and Corvair.
When to plant and harvest spinach if you live in a warm climate
If you live in a warm region where the seasonal shifts are very moderate and winters aren’t very cold, grow your spinach in the winter. Seeds are sown in late fall, and then it’s time to harvest spinach about a month to six weeks later. Tropical growers in year-round hot climates should find an alternative crop. It’s far too warm to grow cool weather-loving spinach in regions where there are never cool temperatures.
How can you tell if spinach is ready to be harvested?
There are a few signs that can help you determine when to harvest fresh spinach. The timing of the harvest depends on the type of green you’re growing. If you’re growing baby spinach, it’s ready to harvest when the leaves are the size of a U.S. quarter until they are about the width of a golf ball. This is about 20-30 days after sowing the seeds. Baby spinach leaves are still round in shape and are very tender.
If you’re growing mature spinach leaves for harvest, wait for the leaves to get thick, broad, and often, crinkled (though not all varieties produced crinkled leaves). Known as savoy-types, those with crinkled leaves are ready to harvest between 38 and 50 days, depending on the variety. Smooth-leaved varieties require the same length of time to mature.
The “baby leaf” harvest
As I mentioned in the last section, the baby leaf harvest happens just a few weeks after planting. If you know when to harvest spinach foliage in the baby stage, you should also know when to stop harvesting in the baby stage. Snip off individual outer leaves but always leave the crown of the plant intact and it will regrow for future harvests. Stop harvesting baby spinach leaves after two harvests. Then let the plant develop mature leaves for a third harvest of fully mature leaves.
When to harvest mature spinach leaves
If you want to pick leaves that are full grown, wait until the plants reach maturity to harvest, but don’t wait so long that the plants bolt. Check the seed packet for the Days to Maturity and consult your calendar. Or go with the flow and harvest it whenever you want! Spinach is a very forgiving crop. As long as you leave the growing point intact, it will grow more leaves until the weather gets too warm and the plant either dies or produces a flower stalk instead of leaves. Some of my favorite varieties for mature leaves are Tyee, Avalon, and Bloomsdale Long Standing.
When to harvest spinach planted in the very early spring
To recap from the first section, if you’re planting seeds or transplants in the very early spring, they’ll produce a mid to late spring harvest. Baby greens will arrive in mid-spring and mature greens will arrive in late spring.
When to harvest spinach planted in the late summer or fall
Late summer plantings are harvested in the mid to late fall or early winter. Baby greens arrive in mid-fall (October in my garden) and continue through early winter. However, you likely won’t see mature leaves until early the next spring. That’s because this crop can easily be overwintered (more on how to do this soon) for a winter or an early spring harvest.
When to harvest spinach planted in the late fall or winter
Planting spinach seeds anytime from a few weeks before the first frost to a few weeks after it, yields a super-early spring harvest. The spinach I plant this way is almost always the very first crop I harvest from my garden in the spring. The seeds sit dormant in the soil through the winter months and germinate very early the following spring. The result is an early spring harvest of baby greens that quickly matures into big, succulent leaves. It’s my favorite way to grow spinach in my own vegetable garden.
How to overwinter spinach for an early harvest
If you’ve opted to sow seeds in late summer or early fall, the young plants can easily be overwintered using one of two different methods.
- Deep mulching. The first technique for overwintering spinach plants is to cover them with 3-4 inches of shredded leaves or straw. Place it right over the crowns of the plants, but only do this just before you have your first hard freeze so the plants don’t rot. Leave them nestled under the mulch all winter long. Remove the mulch about 8 weeks before your last expected spring frost. When to harvest spinach grown this way? In spring, of course!
- Using a cold frame or hoop tunnel. Another way to overwinter spinach is to protect it with a cold frame or hoop tunnel covered in heavyweight row cover or plastic. The plants stay insulated all winter long. You can harvest a small amount of greens through most of the winter (leaving the growing points intact, of course). The plants will begin to re-sprout with the arrival of a few warm spring days. Locating the cold frame or hoop tunnel in full sun generates an early harvest.
Succession planting for even more spinach harvests
Planting a new row of spinach seeds every week throughout the early spring, and then again in the late summer into the fall, generates multiple harvest times. This is known as succession planting, and it is the best way to maximize your harvest. Don’t plant all your seeds at the same time. Spread the sowings out over several weeks. Doing so will also spread out your harvest.
More tips for spinach harvesting
- Pinch vs cut: In addition to knowing when to harvest spinach, how to harvest it is another important factor for success. You can either pinch off individual stems with your thumb and forefinger or cut them off with a pair of scissors or sharp knife. Some gardeners harvest the entire plant using a knife or scissors. That’s a viable technique, too, (and it’s a whole lot faster than leaf-by-leaf). Again, as long as the growing point remains, it will regrow more leaves.
- Manure use: Many gardeners like to amend their soil with horse, cow, or chicken manure in the spring. But if you overwintered spinach and other crops, be sure to keep manure away from the leafy greens. Otherwise you could risk E. coli contamination, even if you think the manure has sat on the compost pile long enough. Don’t risk it.
- Slugs-be-gone: Slugs love to feast on spring spinach. They are one of the worst pests to have in your spinach patch. Use an organic slug bait based on iron phosphate to keep them from ruining your harvest.
It’s easy to see how knowing when to harvest spinach and how to time your plantings properly can lead to a hearty harvest of this delicious green. Don’t be afraid to experiment and plant multiple crops of spinach in your garden to see which performs the best. The results are worth it!
For more on growing leafy greens, please visit the following articles:
- Growing romaine lettuce
- When to harvest rhubarb
- How to grow broccoli sprouts
- 8 salad greens that aren’t lettuce
- Growing lettuce in winter
- Sunflower microgreens
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