Celery Grow Guide

Celery was always an enigma for me. At least, for the first 18 years of growing food. I didn’t so much as ponder growing it. And I don’t think it was because I thought it was hard to grow, it was probably because I didn’t see a lot of photos or varieties in our seed catalog highlighting it. But I sure am glad we found our way with it, because like the garden tomato, homegrown celery is a transformative experience.

I’ve been asked quite a bit this year about growing celery and want to help more people experience and enjoy growing celery, so I’m going to write several installments on growing celery this growing season. First, I will start with this focusing on seeding, germinating and indoor requirements. In a few months, we will revisit our celery as I take my fall celery starts from indoors and plant them out into the garden.

So let’s dig into how to grow 94% water in your garden with a crop that is very nutrient needy!

Celery Varieties

There is not as wide a variety for celery as there is for tomatoes or cucumbers or beans, and this list is by no means exhaustive, but these are four celery varieties I’ve grown over the past three growing seasons.

Utah Tall

This variety didn’t perform well for me in the garden. It had a hollow stem, which literature assigns to uneven watering, however grown side by side with Ventura under the same conditions, this was the only variety to have this issue.

Chinese Pink

It’s pretty, and that’s about it for me. If I were to grow a “pink garden” some year, which is sort of a really cool idea, I would definitely want this mixed in among my flowers and sesame, and the like, but in the kitchen it was tougher, narrower, and more bitter than traditional green celery. I no longer grow this variety — it was a one-time experience for me, but you may need to grow it to see if you’d like it or not. I’m not here to prescribe varieties, just share my experiences honestly.

Tango

We’ve been growing this variety for the past 3 years with consistent results. It makes some really great heads and can be used as a cutting celery too.

Ventura

This is a new variety for us as of last summer, and as mentioned above it grew really well here too. We had a hot and dry summer and they championed through it. I’m growing this variety as a spring and early summer variety in the garden right now.

Culture

Celery, a relative of carrots, dill, parsnips, fennel, and parsley is a very heavy feeder, which is ironic given that it is vastly just a vehicle for water. (Ponders the meaning of life…). Like most vegetables, it grows best in slightly acidic soil (pH 6.0 - 7.0). Knowing your soil pH is super helpful and can be achieved with a soil test performed for a nominal fee at your local agricultural university. If you have alkaline soils, be sure to amend your soil well before transplanting for vigorous growth. Adjusting pH in soils is a slow process that takes months to achieve.

Because it’s a very slow-growing vegetable, you will need to fertilize both upon transplanting and then a second time about 1-2 months after transplanting. More on this in the follow-up guide in July.

Celery thrives in less extreme temperatures, which is why it is a crop most often grown in the temperate climate of the California coast where temperatures tend to hover below 80s but above 50 for most of the year. Literature cites that exposure to repeated lows for more than a week at below 50F/10C will cause it to bolt prematurely. I continue to transplant it along with my earliest brassicas and it hasn’t bolted on me yet, so I’m not sure what to say about that. However, extreme summer heat isn’t its best friend either. I grow it in full sun in the early season, but try to position it in part shade for the fall crop to give it a little bit of moderated temperatures during the brunt of our summer heat.

Finally, celery takes a full season to mature, which I define as more than four months. Sowed in early February, I will harvest my first celery bunch hopefully in mid-June, a full four months later. To achieve this feat, you really need to give the seeds plenty of time to germinate and establish indoors before hardening off and transplanting.

Timing a Fall Celery Garden

Let’s talk timing. I sow my spring and early summer celery in February for an April-May transplanting. With this timing, the plants in 3” pots are vigorous and ready to thrive in the garden. They enjoy the cooler weeks of late spring in which to really establish and take off.

The general rule of thumb from seed companies is to sow celery is 10-12 weeks before frost (either spring or fall). I sow my spring celery 13-14 weeks before last frost. And for fall, my experience has demonstrated that this is a little too late, so I recommend sowing it 18-20 weeks before last frost. Yeah, I know, for some of us, that’s right around our last frost date! This is succession planting at its finest. For those in warmer and milder climates, I think you could get away with closer to 12 weeks before your first fall frost, but I’d still recommend at least 14 weeks just to buffer what can be slow germination rates for some.

For fall, I’ve tried sowing celery in mid-July (12 weeks before frost), then late June (10 weeks), and last year around June 10 (16 weeks before frost). While we grew harvestable celery with the June sowings, it definitely would have been larger and more mature if sowed earlier. I am going to sow my fall celery the week of May 23 this year, 2 weeks earlier than last year. I will plan to transplant it out in the garden after the Fourth of July, around the same time I transplant my June sowed fall cabbages and cauliflower.

Keys to Germination

Water

Let’s grow water. That’s pretty much what we’re after, a crunchy and refreshing vegetable. In order to grow a watery vegetable, you have to provide it with lots of water. And it starts with the seeds. In my research for this guide, I read in a few sources that soaking the seeds overnight can help hasten germination. While I’ve never tried this, if you find celery takes forever to germinate for you, definitely consider this option to add to your sowing schedule for celery.

In addition to potentially soaking the seeds, be sure your potting soil medium is moist before sowing. And retain high moisture by covering with a germination dome, plastic wrap, or other transparent cover on top once you’ve pressed the seeds lightly into the soil.

Light

Small seeds almost always require light for germination. And conversely, large seeds most often need darkness and thus are planted deeper. Celery seeds should be planted on the soil surface. Do not cover the seeds!

Heat

Even though I will be sowing my fall celery indoors in what will be a home above 70F, I will still use a heat mat for germination. It ensures an ideal microclimate to encourage speedy germination. If you don’t yet use a heating mat, you can pick one up online (Disclosure: I am an Amazon affiliate, and receive a small commission from sales through this link).

Keep the heat mat on until germination is complete. Once you are satisfied with germination results you can unplug the heat mat. I usually keep it on for 1 week post-germination, even in warmer months.

Thinning & Potting Up

Because celery takes so long to establish, it is a vegetable that requires potting up before transplanting. One way to get more time out of your pot or soil block is to really be careful when sowing the seeds and only sow 3 per pot. If you sow more — and truly it’s almost impossible not to — it just means you need to take more time with the seedlings to tease them apart and clip the extra ones off at the base. I don’t try to pull them out because they are shallow rooted plants and you will disturb the roots of the primary celery you want to keep.

About 3-4 weeks after germination, your plants should have several sets of true leaves and you should thin them out at that time. Snacking on the seedlings is highly encouraged, a wonderful sensory experience to be sure. Such a bold and bright flavor!

Additionally, beginning a fertilizing routine at this point is also important. I have begun to use a once a week soluble seaweed fertilizer for my seedlings in addition to the compost tea. See my April Q&A here for more details.

These celery are suffering from being overplanted and under-fertilized, as noted by the lower leaves yellowing and dying off. This is a sign of nitrogen deficiencies. While not ideal, it’s a short-term issue that will be remedied upon transplanting the strongest plants into a well-fertilized planting hole.

I grow my celery in 2” soil blocks and thin to one plant per soil block at thinning. I have also had success teasing plants apart and transplanting into a second soil block tray that was empty, although the process required breaking each soil block in half, dropping the seedling in, and then smooshing the soil block back up. It worked. It’s maybe not ideal, but as the plant set roots, it worked to hold the shape of the soil block. The result is a lot of vegetable starts I can donate to the local nonprofit in town who grows for 100% donation!

Once they are looking quite large in the 2” soil blocks, about 5 weeks post-germination, I pot them up into 3.25” soil blocks for their final month or so indoors and their hardening off process. At this point, I am okay growing them on in cooler conditions, and actually had great luck growing them in our basement where temperatures in winter are around 55 degrees. It will be cooler down there in summer too, though not as cool as that, though I plan to grow them out downstairs as well (it’s also where our Roleadro LED 60W full spectrum light is).

Hardening Off

Hardening off requirements for celery are the same as anything else. We are looking to increase stem turgidity by exposing the plants to variable winds, slowly allow the plant cells to acclimate to real sunlight, and toughen the roots up to the outdoor conditions as well by pulling back a little on water and nutrients at this time. More information on hardening off can be found in this blog post.

In late June, I’ll publish the second installment of my Celery Grow Guide so you can prepare your beds and have the best transition for your celery starts.

Who’s growing celery with me this summer? Let me know in the comments!